Vegetables, Sleep, and Sun for a Healthy Gut Microbiome

Does your gut need a reset?

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Do you want to start feeling better?

Yes, Where Do I Start?

Vegetables, Sleep, and Sun for a Healthy Gut Microbiome

An evidence-led approach with Dr. Sarah Ballantyne.

Anything we can do to improve our gut health through lifestyle is a big win. Guest Dr. Sarah Ballantyne a.k.a. the Paleo Mom shares her research-backed tips to support your microbiota, like optimal light exposure, sleep, and vegetable diversity. Hear her clever way to (manageably!) cook 30+ vegetables in a single week, and what nutrients your healthy gut bacteria love.

Episode Intro

Dr. Michael Ruscio, DC: Hi everyone, welcome to Dr. Ruscio Radio. This is Dr. Ruscio. Today I’m here with Dr. Sarah Ballantyne. We are going to be talking about the foundational things you can do to help keep your gut healthy: lifestyle practices, sun exposure, exercise, sleep, which I think sometimes get glossed over for the new and novel XYZ, fancy supplement. But these things are definitely the foundation.

[Continue reading below]

Dr. R’s Fast Facts Summary


Eat a diverse set of vegetables to increase good gut bacteria

  • Tip: Pair vegetables by cooking time
    • Winter squashes take longer, cook them together – acorn, spaghetti, and butternut squash
    • Green veggies cook more quickly – brussels sprouts, asparagus, etc.
  • If your diet is limited due to gut issues, just do the best you can for diversity
  • Fish is a really important food to include in your diet


  • A cornerstone of health that most people find challenging
  • Adults need a bedtime too
  • Stress erodes your sleep quality

Light is the most important signal for keeping circadian rhythm

  • Blue-blocking glasses are good for two hours prior to bed-time, NOT all day
  • Spend time in the bright light of the morning or afternoon to get circadian benefits
  • Warm (reddish) light is best in the evening


Where to learn more

In This Episode

Episode Intro … 00:00:40
An Evidence-Led Approach … 00:03:19
Sarah’s Background … 00:12:14
Vegetable Diversity for Gut Health … 00:16:31
Tips for Getting Veggie Variety … 00:24:58
Handling Food Sensitivities … 00:29:33
Gut Bacteria Are Sensitive to Nutrients … 00:32:43
Sleep, Stress & the Gut Microbiota … 00:37:09
Importance of Light on Circadian Rhythm … 00:40:57
Does Time of Day for Sun Exposure Matter? … 00:45:00
Optimizing Indoor Lights at Night … 00:48:18
Vitamin D & Gut Health … 00:51:18
Episode Wrap-up … 00:54:40

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Sarah and I have been crossing paths at various conferences for a few years now, and I have to credit her with doing a good job of making sure that this podcast actually happened.

But Sarah, I want to share an embarrassing story. When we were at Paleo f(x), I was walking around the floor. I came across your lecture and stepped in for a few minutes to watch. You were going over causation versus association, and I thought, “Oh, by Cupid’s arrow, I think I’m in love!”

Dr. Sarah Ballantyne:   Hahaha!

DrMR: Sometimes I feel like people are so quick to jump to whatever data point they can find to support whatever they’re trying to huck. But in your case you were really trying to help educate a lay audience: “Hey guys, it’s important that you understand causation versus association.” I know that we’re going to have a great conversation today, because I think we have a very similar way in which we analyze data and make our recommendations. So welcome to the show.

DrSB:   Thanks so much for having me. Yeah, that presentation was actually a bonus presentation because a speaker had gotten ill and wasn’t able to make the conference.

The conference CEO came up to me and said, “So Sarah, do you happen to have any other presentations in that backpack of yours?” And I was like, “Well, of course I do. I’ve got about 16 hours worth of presentation back here. What do you need?”

That was a really fun presentation for me to throw in as a bonus, because I’m concerned about this trend that I see happening. For me (as part of the paleo community) I see it in paleo, but I see it in the broader alternative health community where there’s a confirmation bias happening even among these really important voices, these leadership voices in the communities. And I don’t think it’s intentional. I think it comes from, “Well, this worked for me, so this is what I really, truly believe to be true,” or having a lot of stake associated with our brands. We’re all trying to do good in the world, but also make a living while we’re doing it.

An Evidence-Led Approach

I think what I’m seeing happening now is more of a closed off-ness to new information. And as a scientist, my training is to look at new information that challenges what I concluded, based on the information I had up until that point. That’s like the most exciting thing for a scientist, to have to integrate new information into the Zeitgeist of the topic.

And I’m watching, instead, this opposite reaction to challenging information. Of wanting to dismiss it, and wanting to find some reason why that paper is lower quality or not relevant. Certainly, sometimes that’s the case, right? Sometimes there’s a methodological flaw in the paper. Those are the papers that are typically eventually retracted. Sometimes the burden of evidence is on the low side, so we just need to shelf it and wait until there are new studies. But I think most of the time there’s information there that we need to look at, really think about, and try to integrate.

My approach is always to seek the context and the nuance rather than dismiss something because it doesn’t conform.  So I think of this as being a very evidence-led approach. I’m looking at the evidence and letting the evidence lead my recommendations, rather than seeking the evidence that happens to conform to my recommendations.

DrMR:   Right. And as I suspected, we have a very tight agreement here. The way I’ve described this on the show in the past is that some people will use evidence to inform and to learn, and other people will just selectively cite whatever reinforces their pre-existing beliefs.

DrSB:   Yes.

DrMR:   It’s really hard for the healthcare consumer to know who’s telling the truth and who’s not telling the truth. Because they see references, and it’s hard to know, “Well, is this a high-quality reference or a low-quality reference?” I think one way the audience can help safeguard against that is… one, are there even references present in the post? Two, are the references put in line? Meaning, you say, “Controversial point X,” and then there’s a reference. That gives you a higher degree of veracity of the statement perhaps, as opposed to someone who just has a bunch of references listed at the very end of the article, with no index to what points they’re supporting. In an online article you can always do this format, but I think in-line references help.

Then if you ever do look at the reference itself, and I encourage people to do this, if you see something that’s done in a Petri dish or a cell-line culture or an animal, we should really be cautious with the kind of recommendations that we’re pulling from there.

But if you see something that reads along the lines of, “30 women with X condition were given either placebo or this,” and you can look in the abstract and get a sense, “Okay, it seems like what this person is saying is supported by the reference that they’re using to support it,” that can go a decent way to help you parse through who is just using references as marketing in a cherry-picking fashion, compared to who is really trying to be, to some degree, upfront. As you said, evidence-led, rather than marketing masquerading as science.

DrSB:   So I want to challenge you on one aspect of what you just said. Because I put a large amount of weight on what I qualify as mechanistic studies, so these would be the studies in animals or in a Petri dish that are not intervention studies. Animal studies and cell culture studies can fall under these two different umbrellas.

One is an intervention study, which would be the “I have this animal, I gave it this drug or put it on this diet, and I observed this effect.” Those are the studies that I would definitely agree don’t necessarily translate to humans. In fact, I think they translate to humans of a fairly small percentage of the time, just because of the metabolic differences between animals and humans.

But the vast majority of research that is done in animals or in cell culture are studies that are designed to isolate the mechanisms. I’ve made the observation in humans that when I put them on this diet or I give them this drug, or whatever causative agent I have occurs, and I observed this effect, the animal study or the cell culture study is designed to explain, is that a direct effect? Does A actually directly cause B or are there steps in between? In that case it’s the combination of that animal study with the human study that is very, very powerful information. And it’s a little bit of a different situation.

Like, in drug studies, they do these intervention studies where they give animals drugs, and they measure an effect, and that’s part of the development of a drug before they do human clinical trials. There’s a very high rate of the drug not working as expected by the time it gets to humans. But I think when it’s about understanding cell signaling, like, what protein is being turned on? What enzyme is active? What is being produced by this cell that explains this effect? That’s where I see—sort of what I consider more basic science research—these mechanistic studies as being very, very powerful.

The challenge with that is that you have to pair it with the human data. And I think it makes it harder for a person without a science background to be able to parse. I think it’s very valuable information because it explains that the effects that you’re observing actually have a chemical reaction pathway to explain them. But it makes it, I think, a little bit less accessible for the average person to really get in there, and understand whether or not that is quality evidence.

DrMR:   It’s a great point. And I guess the nuance there that’s important, and you addressed it in your comment, is we need to have the human outcome data also.

DrSB:   Yeah.

DrMR:   Where I think the huge miss often is someone wants to support a given point, there is no human data, and they just speculate wildly from mechanism. The challenge with mechanism alone is, mechanisms oftentimes don’t pan out to have the desired user effect that we’re hoping they will. Sometimes they do, sometimes they don’t.

But I think we need to have the outcome first: “Intervention X produces positive result Y.” Then we can use mechanism data in conjunction with that to understand what’s going on underneath the hood.

But what I’ve observed so often in the internet is there’s not good data, or it’s kind of a heretical claim, or they’re rushing to try to sell something oftentimes. And all they’re doing is just citing mechanism studies, sometimes ignoring the outcome data that refutes that, or they’re going way, way too preclinical.

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This is happening with a lot of peptide research. And I’m open to it, I think it’s exciting. But until we know what happens in humans when we pump that mechanism in a certain direction, I’m pretty cautious.

So I think we’re saying the same things there. But you do make a good point, which is, if you see a mechanism, it’s not a bad thing, but you should also be looking for a tie to some kind of outcome study with humans.

DrSB:   Certainly, exactly like what you’re saying, in the context of somebody selling you a supplement or medication, or even selling you a dietary template or a lifestyle hack. Those things require … It’s not just about understanding how it works, you need to understand the magnitude of the effect, and whether or not there are any additional effects that are not measured when you come to humans.

That’s where looking at side effects and adverse reactions becomes really important. Especially with these mechanistic studies, you can really get into the weeds, in terms of understanding this one particular pathway, without necessarily noting, “Oh, but there are three or four other pathways that are turned on at the same time.” So when you go to translate that to a recommendation for a human, maybe pathway four is so detrimental that it makes the benefit of pathway one completely moot.

DrMR:   Exactly, yeah. So, good. We’re in agreement.

DrSB:   Sweet. Haha!

Sarah’s Background

Vegetables, Sleep, and Sun for a Healthy Gut Microbiome - book%20rotated L

DrMR:   So I know you’re knee-deep in the stream of microbiota research occurrent, and you wanted to talk about some of these foundational aspects for supporting the gut in a healthy way. This is something we’ve talked about in the podcast before, and I also talk about in Healthy Gut, Healthy You, which is how important these things like sleep, Circadian rhythm, stress, exercise, sun exposure are. These have been shown not only to have positive health outcomes for the host, but also improve the microbiota to various degrees.

I’m sorry, let me take a big step back. Tell us about your background. We glossed over that, in case someone listening to this or reading this hasn’t heard of you before, give us the quick primer there.

DrSB:   Oh, sure. I’m really excited to jump in to the nerdy topics–

DrMR:   Yeah, same here!

DrSB:   –but I do have some credentials that allow me to talk about nerdy topics in an informed way. So I have a medical research background. I earned a PhD in Medical Biophysics at the age of 26, and did four years of medical research at the post-doctoral research level afterwards, before my health really forced me to re-evaluate my entire life.

I took time off which ended up being more permanent that I originally anticipated. While I was trying to focus on my own health and motherhood (because I had a couple of kids in that period of time), I accidentally created an entirely new career for myself as a sort of health educator. I consider what I do to be very much bridging the academic world—that I used to be completely immersed in—with the general public, and really bringing the information that researchers are learning.

Their whole career is dedicated to expanding human knowledge. And yet so much of what researchers are discovering—and this isn’t just in medical fields, but this is across sciences—takes decades to permeate into the education system or the medical system. It’s relevant, and yet the average person doesn’t learn about the relevance until decades later.

So I consider myself the fast track between looking at what researchers are doing, and helping people understand how that actually might inform a choice and positively impact their lives. I came to that by… I struggled with over a dozen different diagnosed health conditions. I was morbidly obese. I have four autoimmune conditions.

And I was working in some of the highest profile labs in North America, 80 or 100 hours weeks, doing really top-level research, award-winning research. And just in so much pain all of the time, and really unable to really enjoy life. It really was something that if I hadn’t been so ambitious and stubborn… I sometimes look back at that, and I’m like, “How did I do that one experiment that took 22 hours? And how did I do that in the lab when I felt so terrible?” I can only assume that it was just a complete desire to ignore my own body at the time.

But it was finding answers in that space—when I decided to take my time off of medical research—and losing 130 pounds, reversing most of my health conditions, putting my autoimmune diseases into remission, that has given me a different perspective. And also, it’s just highly motivating to be a communicator.

The reason why I was so challenged for so many years with my health was because I didn’t have access to that information. And there’s no reason why I shouldn’t have had access to that information. That should have been something my doctor mentioned to me when I started gaining weight in a way that was disproportionate to my diet and lifestyle when I was 12. “Hey, have you tried gluten-free?” It should have just been automatic. So I’ve really found myself taking that mantle on.

Vegetable Diversity for Gut Health

DrMR:   And now you’re really trying to dig in to the microbiota specifically.

DrSB:   Yes.

DrMR:   Definitely preaching to the choir there. What are you finding of late that’s interesting in this realm of lifestyle-ish interventions that can improve our gut health?

DrSB:   To me this has been the most fascinating topic to dive into. I come from the paleo community—my blog is The Paleo Mom—and from the autoimmune protocol, which is a variant of paleo designed to maximize nutrient density, and minimize inflammatory compounds for people with chronic illness. And I look at the research on the gut microbiome and I’ve started to really see, not just the basic principles of paleo or the autoimmune protocol, but really all of these dietary approaches that have some good science to support benefits. It’s not just paleo that has potential health benefits.

I’ve started to look at all of those different recommendations through the lens of the microbiome. That has been really empowering information for me to really dig into, and start to understand in terms of dietary principles, that it’s not just about fiber quantity, it’s about diversity.

We have some really desirable strains of bacteria that have really limited capacity to ferment carbohydrates. There are only a few types of carbohydrates that they really ferment with any kind of efficacy. And they are some of the most desirable species, but if we’re not eating those types of fiber, then they die off really quickly.

Like Bifidobacterium, which are one of the most fundamental probiotic genera of bacteria in the gut, are finicky. They really are picky, they like to live with their friends. They’ve got certain friends that they really like hanging out with, so there are Bacillus species they really like being around, Methanobrevibacter they really like being around. They really like this community.

And if they don’t have the right neighbors, then they die off. If they don’t have the right food, then they die off. If we’re stressed, they die off. If we’re not getting enough sleep, they die off. If we’re vitamin D deficient, they die off. They’re really the canary in the coal mine, in terms of what’s going on.

DrMR:   Sarah, let’s clarify one thing really quick, just so our audience doesn’t jump too quickly. When we say die off, you don’t mean permanent, irrevocable, lost–

DrSB:   Oh, of course, no.

DrMR:   Okay. Just because sometimes people get really concerned when they see fluctuations and they go, “Oh, my God, have I lost these, and they’re never going to come back?” So it’s a dwindling, right? Not a complete loss.

DrSB:   Yeah, that’s a really good call there. I think what is very empowering knowledge out of this is how resilient our gut microbiomes are. Various little pockets within the GI tract where small amounts of these types of bacteria will survive, so that when the conditions are better for their growth again they can return.

It actually takes a very small amount of time for our gut to change dramatically, both in a positive and a negative sense. So if you’re coming from even an antibiotic treatment, something that… Obviously there’s a time and a place, antibiotics can be life-saving medication, and if that was the case you would want to take it, despite what it will do to your gut bacteria. There are some really good studies showing that the gut microbiome can recover. And depending on diet and lifestyle, it can recover very, very quickly.

So that I think is really empowering information to know, that these changes are generally not permanent. There are lots of things that we can do to bring those guys back, and support them. And especially the species that we tend to have frequent exposure to in our environments or in our foods, those are the ones that are generally the easiest to get back up to good levels, with a few small changes.

DrMR:   Awesome. I cut off your thought there, but do you remember where you left off?

DrSB:   Diversity. I think that’s been one of the things that has been really eye-opening for me, as somebody who’s been on the vegetable train for a while. To recognize that there’s this difference between how, say, hunter-gatherers in the world, or historically-studied hunter-gatherers lived. They typically will eat like 100 to 200 different plant species on a regular basis.

And if you are buying every single possible option in the grocery store, you may have access to 50 different plant species. To realize that that diversity of how hunter-gatherers naturally eat is driving diversity in the gut microbiome, in a very positive way by feeding this community aspect of the gut microbiome, is really interesting for me to wrap my head around. A large part of what I’m doing as I look at the research is not just trying to understand the basics and the fundamentals, but how do we apply this to our modern day lives.

That has been a really interesting one: “Well, how do you find that diversity in the modern food supply?” And you can! That’s the really cool thing. I started to think of vegetables as their own food groups, like leafy greens is a food group, and the cabbage family, cruciferous vegetables, is a food group. Mushrooms are a food group, and root vegetables is a food group. The apple family of fruit is a food group, and berries. And nuts and seeds are. I tried to think of how I can hit as many of those food groups on a two to three day rotation as possible, to really make sure that I’m getting the different types of fermentable substrate, which is mostly fiber, but also some types of starch that are in all of those.

DrMR:   I think that’s interesting. What was helpful for me in looking at my diet log in Cronometer—I’d been tracking that for a while—was to see a couple deficiency patterns evolving. That was really a good kick in the rear for me to say, “Okay, I need to do a better job of not just eating the same seven or so vegetables that I typically eat.” I think we could all do well to really try to expand our diet as much as possible.

You bring it to an even better level, which is different types of mushrooms… not just a mushroom, maybe we’re setting the bar too low saying we’re going to eat Portobellos, but maybe we need to try to have different mushrooms, and different root vegetables, rather than just selecting the one root vegetable or one mushroom or whatever. I think that’s a great idea.

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Do you have any tips for people who are maybe wondering how they can get the ball rolling with it? Obviously they can go to the store, and try to buy more diversely. But any tips there as you’ve been doing that yourself?

Tips for Getting Veggie Variety

DrSB:   Yeah, so this is one of those things that has really changed how I shop, cook, and eat. One of the things that I have started doing now (I’ve been a farmer’s market junkie for a while) is I start my shopping at the farmer’s market every Saturday, and then I round it out from the grocery store. Farmer’s markets are amazing because you can get access to heirloom varieties, just different cultivars that you’re not necessarily going to find in a grocery store. If you have access to a farmer’s market that is a great resource.

I even have one local farmer who just had a brand new variety of squash volunteer on their farm, and they are currently propagating it. It’s being named as a new species after their farm, which is, like, the coolest thing. That means that I get to have this completely unique squash that, right now, no one else in the world can eat.

So farmer’s markets are an amazing resource. I used to basically make two or three different vegetables at dinner. That was my standard. I would buy a couple pounds of Brussels sprouts if I was going to make Brussels sprouts one night, and I would buy a couple of pounds of sweet potatoes if I was going to make sweet potatoes one night.

What I’ve started doing is buying like a pound of each thing. I really think of it as like going down the aisle and getting one of each. Then you kind of have these vegetables that take a little bit longer to cook, and you have vegetables that are a little bit faster to cook. So I just divide them that way.

Instead of the whole bunch of asparagus, that bunch of asparagus I’ll maybe cook three times. I’ll grab a third of the bunch, some chard, some shiitake mushrooms, and maybe I’ll finally slice some Brussels sprouts so they’ll be a fast cooker instead of slow cooker. And I’ll throw them all in a sheet pan with a little high-quality olive oil and unrefined sea salt, and roast them. Those, the fast-cooking vegetables, will roast in 10 or 12 minutes.

And if I wanted to do another tray, that one would have the winter squash, parsnips, and sweet potato, and that one will take half an hour. But I sort of divide it that way. I can put one in the oven 30 minutes before the meal, and then the other one in the oven gets added 10 or 15 minutes before. That way each sheet pan has three to six different things on it, and it’s completely changed the amount of variety that I can fit into each meal.

But also throughout the full week (like the arc of the week), I’m getting maybe 30 to 35 different vegetables, as opposed to probably seven to 10.

DrMR:   That’s great. The insight of trying to pair vegetables by cooking times, so as to make your cooking easier, is brilliant. Because I don’t think anyone wants to be sitting there, manning the stove, just having to slave over the oven in order to make sure you don’t burn something, or something’s undercooked. I would see that being very much able to make it doable. Because that’s one of the challenges I always bump up against, as much I’d like to pick up a cookbook and make some of those meals. Some of the recipes are like, “Geez, who has two hours to make this meal?”

DrSB:   Once every three months on a Sunday. But I do gravitate towards very low hands-on, time-tight foods. I work from home, so I can put something in the oven at two o’clock in the afternoon if I need to. But I tend to gravitate towards things that are a lower amount of my time. So I don’t put a lot of effort into chopping things evenly, I just chop them quickly.

And if one ends up being a little crispy on the edges, or a little bit softer, and the other one ends up being a little bit firmer, to me that’s interesting, because they taste a little bit different. What’s really interesting too is that cooked fiber versus raw fiber supports different species of bacteria. So you actually get a different effect on the gut microbiome eating that broccoli cooked versus raw.

And even though there’s not data to support it, my interpretation of what is there is that there would be a gradient of effect in between. So if my vegetables aren’t cooked completely evenly, to me that’s adding a different kind of variety, a variety in the cooking method as opposed to the vegetable itself.

Handling Food Sensitivities

DrMR:   Now, one of the conversations that comes up here is, “How do we handle situations where someone has non-optimal, for lack of a better term, gut health, and they have some sensitivities they have to eat around?”

I think in the IBS, in the IBD populations, this is a message that is frustrating. People are saying, “Oh, you know, I’d love to expand more, but I have limitations.” My perspective is, do the best that you can with your current situation. And if you’re working with a competent clinician, you should see improvements over time.

Some people are going to have better tolerance than others, and I think it’s important that we all shoot for as broad as we can, but be okay with the limitations that we’re able to or that we have to work within. What are your thoughts here? Do you have any insights that might be valuable for our audience?

DrSB:   Yeah. I generally agree with that approach. And I think that when we start getting stressed about the foods that we’re eating, we’re undermining the health benefits that we can get from those foods because of the detrimental effects of stress.

The idea is to make eating a healthy diet as natural as possible. It just fits into our lives, rather than us trying to fit our life into that diet. It’s a very different way of thinking about it. But I think there is also this tendency to want to make big changes all at once. I’m a person like that. I want to just, “Oh, wait, that’s the thing I need to do. I’m just going to rip off the Band-Aid and jump all in.”

And I think that when you’re dealing with some kind of underlying health challenge—and this could be something like severe gut dysbiosis, that means that you’re having GI symptoms when you try to increase your vegetable intake—I think that there is a slow and steady approach to this that can be really, really effective (obviously this would be, again, working with a competent practitioner). “Well, let’s stay sub-symptom, and work on every week or every few days. Let’s try to add a quarter serving of vegetables to this meal, and increase your tolerance to these foods gradually.” That tolerance is actually a strong reflection of the shift in gut microbiome that is occurring because of that dietary shift.

I think that for a lot of people, there are ways that we can slowly work around some of those limitations with some patience, and get to a place where we can expand our dietary choices. But again, it’s sort of like a slow-and-steady-wins-the-race approach.

DrMR:   Agreed, and I’m glad that you said that, because I think that’s something important for patients to keep in mind. That we’re all trying to be better today than we were yesterday, but not as good as the best person today. I think that’s important to realize.

We’re all on our own journeys, and as long as you’re making slow, steady progress, then I consider that a win. Also like you said, don’t stress out about it because then you’ll be working against yourself, because obviously stress has negative health ramifications.

Gut Bacteria Are Sensitive to Nutrients

Where else do you want to go? Is there anything else on diet that you want to go into? Do you want to touch on something else like sleep or sun or exercise?

DrSB:   Oh, gosh, there are so many different directions we could go. It’s so challenging. I think the other thing about diet, just one of the little knowledge bombs to drop and let lie there, is our gut bacteria care about more than just fiber, and more than just diversity of fibers. They’re sensitive to the nutrient density of our diet. They have essential nutrients just like we do.

And if we’re not consuming enough of those nutrients, they’re not particularly happy. They’re sensitive to the types of fats that we’re consuming. They really like omega-3 fats, just like we do. They really like high-quality olive oil. They really like those polyphenol-rich monounsaturated fats, just like we do. They thrive under fish protein. Fish protein is, like, the magical protein.

They also really like pea protein. But soy protein is terrible. And as you start to dissect some of the other foods that are really important, phytochemicals are really important for the gut microbiome. It starts to form a really cohesive message of lots of vegetables, high-quality animal foods in moderation, and lots of variety and heart-healthy fats, are the theme that also supports a really robust, resilient, and diverse gut microbiome.

DrMR:   It’s funny. One of the things that I’ve said in the podcast before hearkens back to a pretty impressive analysis done by Loren Cordain. It was at such odds with much of the narrative you get in the paleo community, which was, “Grass-fed beef! Beef, beef, beef, beef, beef!”

But as he examined the hunter-gatherer populations that went farther away from the equator, he found that the main food that changed was an increased consumption of fish in the diet. So that totally dovetails with what you’re saying there.

DrSB:   Yeah. If I’m going to criticize my own community here for a second, I think one of the things that the paleo diet in its most commonly communicated form has done is give people this carte blanche to consume as much fat as we want, and to consume saturated fat in as high quantities as we want. We see this magnified with low-carb paleo combinations or ketogenic diet paleo combinations. And I don’t think the science supports health benefits for that really high fat intake.

I think one of the things that Cordain’s analysis really emphasized was that even in populations that are far away from the equator, if you look at the Inuit, for example, yes, they’re eating a large amount of animal foods, but they’re actually going so far out of their way to get plant foods. They eat the stomach contents of every animal, whether they come from land or the sea, so partially digested grasses and algaes and seaweed.

But when you actually start to look at these diets, you see that the fat content is not actually that high. You see, at most, in the high 50-ish percent as a percentage of total calories. And most hunter-gatherers are more in that 35, 40% as a percent of total calories range. I think that that’s pretty easy to get if you just stick to whole foods, and you don’t go crazy adding grass-fed butter to all of your food. But I think that it’s one area where the eat-like-a-caveman meme has sort of steered us the wrong way.

DrMR:   Yeah. I think it was a great aspect of the message to help us understand that fat wasn’t the enemy.

DrSB:   Right.

DrMR:   But I think we went a little too far in that direction.

DrSB:   Yes, we got very excited about fat not being the enemy, and kind of overdid it.

DrMR:   Yep, and rightfully so. I love fat, but I have learned personally that if there is one food that I will overeat easily it is fat. I can down a block of cheese like nobody else. Hahaha. I’ve learned I have to kind of bridle that, because it’s way too easy to overeat in that area.

DrSB:   Yeah.

Sleep, Stress & the Gut Microbiota

DrMR:   Okay, where else should we go?

DrSB:   Well, let’s talk about lifestyle and the microbiota. I think whether you’re talking about somebody who wants to make changes because they’re struggling with illness or they want to lose weight, or they want to perform better at their sport—all of these different entry points to what I’ll sort of broadly put under the umbrella of sort of alternative health communities or health-conscious communities—I think that it’s really easy to get very focused on diet, and get into that minute detail of diet.

Other than exercise, exercise is kind of an easy one for people in these health-conscious communities to tackle. There’s functional movement, and all these great things that have come into this arena. But managing stress and getting enough sleep are still the messages that people often don’t want to hear. There are a lot of reasons why doing those two things are really important from an immune regulation perspective, from a hormone perspective, but also from a gut microbiome perspective.

And it’s really dramatic how not getting enough sleep and chronic stress are impacting the gut microbiome. And I think it’s worthwhile just talking, to give maybe another check in the pro column for why going to bed eight hours before your alarm is going to go off in the morning is a really good idea.

DrMR:   I think that’s not always as easy as I would like it to be. But definitely something I’ve been making more and more strides towards. Personally I feel a big difference. So you feel people want to have an in-bed window of eight hours. Are there any kind of benchmarks, tracking devices that you think are important for people to incorporate in this endeavor?

DrSB:   I’m a person who is incredibly sensitive to the amount of sleep that I get, and I struggle with poor quality sleep. So it’s one of those things that I have to be incredibly diligent about. I make choices throughout my entire day that are geared at improving sleep.

I think that the biggest challenge for most people is just the routine of it. There are really interesting studies in obesity research looking at sleep timing and obesity and diabetes risks. Showing that if we sleep on a consistent schedule, it basically dramatically reduces our risk of obesity and Type 2 diabetes. That the higher the variation is in terms of when we go to bed, when we rise, and also the length of sleep that we’re getting, again, the higher our risk of obesity and Type 2 diabetes.

I think that that’s a really interesting piece to the puzzle. My kids have a firm bed time. Like, they have to go to bed at a certain time, and that’s because if they don’t go to bed on time, they’re cranky the next day, and I don’t like them very much. And we’re pretty much all miserable as a family. I think it’s really easy for parents to see in their kids, but not necessarily recognize in themselves. I really think that adults need a bedtime.

Sleep and stress really feed into each other. So one of the most stressful things that we can do is not get enough sleep, and one of the best things we can do to make ourselves resilient against other stressors like work and bills, and traffic, is to get enough sleep. But being stressed will erode our sleep quality. There is a lot of crosstalk in those two systems. So looking after the other things like managing stress to improve sleep, and Circadian rhythm entrenchment to improve sleep…

The Importance of Light on Circadian Rhythm

My daughter, my 12-year old daughter just got glasses this week. She was given my husband’s eyesight. I’m kind of surprised that she made it all the way to 12 without them. We went to the optician, and the default lens was a blue-blocking lens. This is the new trending thing for eyeglasses. I looked at it, I was like, “Well, wait, what wavelength does it block?”

“450 to 550. Isn’t this great? Because this is responsible for blocking melatonin production.”

I said, “Well, sure, in the evening!”

DrMR:   You want it during the day, yeah!

DrSB:   But our exposure to blue light wavelengths in the day is what supports dim light melatonin production. I read one study on the subject, but not the full three studies I needed to read to be able to make this product. And I saved a ton of money by requesting the non blue-blocking lenses, but it was interesting to me the lack of awareness of how our lighting is impacting our sleep.

So we spend our entire days indoors, which is not bright enough to support melatonin production in the evening. And then we use lights in the evening to do all the fun things that we like to do in the evenings, because we’re finally home from work, and spending time with our family, and watching all the television, going on Facebook, and whatever it is. And those lights are far too bright to support our sleep.

So it’s a really simple hack to either use a light therapy box on your desk or make sure that when you have your lunch hour, that you go and eat outside. Spend some time in that bright light environment. And then turn the lights off in the evening. Save electricity too. Or use red light bulbs, or you can get super fancy and get Phillip’s Hue light bulbs that you can program to turn red for the last few hours of the night. Or that’s where the blue-blocking glasses come in handy, the last two to three hours of the day.

But our light is our number one, what’s called a Zeitgeber, which means anything that influences our internal biological clock or Circadian clock. Light is by far the most important signal.

And also with increasing public education on this topic, it would be a very easy thing for us as an entire society to implement. We just have to have that piece of the puzzle that is, like, “Hey guys, we should, A. Go to bed and all have a bedtime, and B. Prepare our bodies for it by making sure we get the right light exposure at the right time of day.”

DrMR:   A few followup questions there. I completely agree. It’s funny, I was on Instagram the other day, and I saw someone saying how they love their new blue-light blocking glasses. And they were taking a video of themselves using it during the day. Haha.

DrSB:   Yes. It’s become a thing for, like, eye strain, using a computer. It’s a recognition of… blue light, because it’s a higher energy wavelength of energy, can oxidize oxygen-based molecules. It can cause oxidative damage to DNA, it’s part of photoaging of the skin. It’s well-understood in the scientific literature that aging is accelerated by blue-light exposure due to oxidation.

But of course, a lot of the choices we’re making are about increasing our consumption of antioxidants, supporting our antioxidant pathways in our body. And it’s important to recognize that blue-light exposure also serves a really important purpose. How can we utilize that really important purpose? How can we get those great benefits to Circadian rhythm entrenchment?

Well, also, it goes back to consuming more vegetables, that’s where we’re getting most of our antioxidants from. So when you start to take that step back and look at it more holistically, it makes a lot of sense. But yeah, I’m seeing that same trend of, everybody wants blue-blocking glasses. I’m like, “They’re great for 7:00 to 10:00 PM.”

Does Time of Day for Sun Exposure Matter?

DrMR:   Yep. Some have said that it’s important to get direct exposure to sunlight early in the morning. And I’m unclear on if you get some time outside in direct sunlight, any time maybe before one or two, if you can get the Circadian benefits. Do you know, is there any specific recommendation? Is it essential to get some time in the sun in the morning or could you get away with just doing it at lunch? Is there a nuance there?

DrSB:   Yeah, I don’t think the science is super strong on whether or not there is an optimal time of day. The angles of the light coming at you are obviously different depending on how high in the sky the sun is. This is where I take the science that is out there, and make an inference based on it.

So let’s be perfectly clear, I suspect that we are very well-attuned, like we have some kind of internal sundial. That there is a corrective factor in our clock genes that goes, “Okay, a sun exposure, and that’s where the sun is, so that’s what time of day it must be.” I think that’s also why you see seasonal variation in sleep patterns with people who are getting a lot… I guess, in hunter-gatherers, in the “olden days” there was seasonal variation in term of our sleep patterns. We would sleep a lot more in the winter, and part of that was the nights are longer. But the other part of it is, the sun’s not as high in the sky.

I think that it’s very likely just important to get outside at some point in the day, and kind of let the brain sync with where the sun is in the sky at that time. That’s based on this collection of research that makes it clear that exposure, especially in the first half of the day, is really important. But there are people who get up to see the sunrise every morning, and it doesn’t really make clear that that would be any better than going for a walk at lunchtime.

DrMR:   That’s a really interesting posit. It makes sense, the brain is able to determine if this is midday sun because it’s bright, or morning sun because it’s not as bright. That makes a lot of sense.

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Optimizing Indoor Lights at Night

Coming to the red lights you mentioned, are there certain lights people should be using at nighttime? One of the things I think people grapple with is that they don’t like dimming lights. I personally kind of like having the lights more dim, and I’ve been able to adapt to less lighting at night. But when I’m with friends or family sometimes: “Oh, I can’t see anything.”

Is there an ideal kind of bulb someone should buy if they’re saying, “Okay, well, I can’t get everyone in the house on board with the dimming. We need a little bit more light”? Should they be looking for a red light, an orange light? Is there a certain bulb they should be looking for in particular?

DrSB:   Yeah, generally the redder you go the more it’s replicating… think about the sun setting, those wavelengths. The light is highly scattered because that light is traveling through more atmosphere than it is at any other time during the day. And that is lengthening the wavelengths to red wavelengths.

So I think it’s interesting that that seems to be such an important Circadian rhythm signal, the lights turning red. The redder we go, the better we’re supporting dim light melatonin production in those last two to three hours in the evening. And you can do things like programmable light bulbs that can change color. I have those in all of our bedrooms. So in all of our bedrooms—as the kids retire in the evening, as we retire in the evenings—those lights are always red. We actually keep them dim as well, so we keep them dim and red.

What’s good about doing that is that there are photoreceptors in the skin. So our most sensitive photoreceptors are in our eyes, but it’s not the only place where our bodies are detecting the light environment.

I would say, either look at red light bulbs… you can do the 60-cent red light bulb in a lamp, it doesn’t need to be the really expensive programmable LEDs, but red wavelengths in the evening, or you can do dimmer choices, like turning off the overhead lights. Definitely turn off fluorescent lights. And reduce the overall light, and then use blue-blocking glasses in the evening as sort of another way to go.

But I think also that night vision is really tied to our antioxidant status. So it’s another really interesting entry point into this more holistic approach: “Well, oh, it’s really dim,” and you’re having a hard time reading in this dim environment. Maybe eat some vegetables.

DrMR:   Haha! Well, now I have a rhetoric for when people are complaining.

DrSB:   You know, it’s not going to go over well! I’m just going to let you know right now. It’s going to be better just to turn on a light bulb, at least.

DrMR:   You’re probably right.

DrSB:   Hahaha.

Vitamin D & Gut Health

DrMR:   Then also, there are these nice gut benefits that we see in the research from sun exposure.

DrSB:   Yeah.

DrMR:   Some studies showing reduced inflammatory bowel disease, reduced diverticulitis, just to name a couple. The research here is definitely in its nascency, but—and I’m not sure why this is in the model of cystic fibrosis—there are some studies showing that cystic fibrosis patients who use vitamin D have an improved microbiota. It makes sense if vitamin D is helping to regulate the immune system, and the immune system partially regulates the contents of the microbiota, that there are some logical mechanisms there.

DrSB:   There are actually quite a few different health conditions that vitamin D deficiency is associated with. A loss of diversity, and reduced levels of certain really important probiotic strains. But you’re leading to something that’s really fascinating to me, which is, there’s an independent benefit between getting your vitamin D levels back up, which I definitely think is important… but it’s not just about vitamin D. There also seems to be this response to sunlight.

It could be mediated through the stress axis, because when you’re outside you’re typically also exposed to nature. We know that that reduces HPA-axis activation, so it could be mediated through stress or it could be mediated through Circadian rhythm entrenchment. It’s really early days in the literature, but there does seem to be a Circadian rhythm of the gut microbiome.

Basically our gut bacteria also know what time of day it is. And they change their activity level based on the time of day. So it might be about entrenching their Circadian rhythm in addition to our own, because our gut bacteria are sensitive to our hormone environments, so it might be about synchronizing with them. But wherever in the mechanisms that falls, I feel like that’s still a really, really open question.

It does make a strong case for going beyond just testing vitamin D levels and supplementing to get them in a normal range, and really go to, “Well, why are your vitamin D levels low to begin with?” Certainly sometimes it can be a genetic variant that makes you a poor vitamin D synthesizer. But normally we would be getting vitamin D from the sun. That would be the vast majority of vitamin D that we get if we make it out of cholesterol in response to UV radiation.

There’s something about those pathways that are triggered when we’re out in the sun that are particularly beneficial, and worth prioritizing, even in the context of, “Yeah, but I take 5000 IU vitamin D a day, and I know I’m fine.”

DrMR:   Yep, I agree completely. And we’ve covered this concept many times in the podcast, but it’s always important to mention it one more time, which is, you cannot get all the benefits from sun exposure by supplementing with vitamin D. They are independent, and you need to have the sun exposure to get all the benefits.

DrSB:   I would extend that to any diet and lifestyle thing that we know is healthy for us, in any pill.

DrMR:   Yeah, agree, if you can do it with diet and lifestyle, that should be your go-to. Absolutely agree.

Episode Wrap-Up

Where do you want to point people online?

DrSB:   So my website is From there you can link to my social media, my podcast, my online courses, my books.

I know we’ve tangentially talked about the autoimmune protocol and the paleo diet a little bit, but if your listeners would like they can go to, and I’ve got a free paleo quick-start guide, and a free autoimmune protocol quick-start guide that are quite actually comprehensive, that can give people more information not just in terms of what those things are, but also my contemporary science-rooted approach to both of those templates.

DrMR:   Great, love it. Okay, any closing thoughts or advice you want to leave people with?

DrSB:   I’m going to leave people with a note of optimism, because I always think that’s really important, especially when we get into the weeds a little bit. I think one of the things that’s really empowering about this is, it’s another lens from which to understand why the things that we already know are good for us are good for us.

It also shows us that the more good choices we make on a day-to-day basis, that those benefits compound. But it doesn’t mean that we need to be perfect, because there are lots of good choices to make. And we can do the best that we can, and get a lot of benefits from doing that.

I think approaching healthy living as a journey is a really important mindset to be in. If we set ourselves up with such strict guidelines that we can’t stick to it, then it’s not going to benefit our health because we can’t be making those healthy choices for the rest of our lives. So I really want to emphasize that this is about understanding those things that are optimal so that we can make our progress towards that.

DrMR:   I think that’s great advice. And I see in the clinic people have a tendency to fixate on just their diet, and then they can neglect lifestyle aspects sometimes. The example that runs through my mind as you say that is, for the person who is frustrated by their diet having to be a little bit narrow at the moment, then be okay with that, and focus more on the other things you can do, like your stress, your sleep, your time in the sun. The diet will get better with time, but don’t put all of your healthcare eggs in one basket, so to speak.

DrSB:   Yep, exactly.

DrMR:   Awesome. Well, Sarah, it’s been a real pleasure chatting. I knew that we would have a great conversation. Thank you so much for taking the time. It’s been a very insightful and interesting conversation.

DrSB:   Thanks again for having me.

DrMR:   Yeah, been a pleasure.

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