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Evidence Based

This article is based on scientific evidence, written by experts and fact checked by experts.

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This article contains scientific references. The numbers in the parentheses (1, 2, 3) are clickable links to peer-reviewed scientific papers.

The Best Hair Growth Supplements for Fuller, Stronger Hair

Written by Dr. Michael Ruscio, DC on June 5, 2025

Written by Dr. Michael Ruscio, DC on June 5, 2025 — Reviewed by Hilary Watts

• How Hair Grows|
• Hair Loss|
• Nutrition for Healthy Hair|
• 9 Key Vitamins|
• 3 Other Hair Supplements|
• 5 Hair-Stimulating Habits|
• Summary of the Best Supplements|

Hair is more than just a style statement—it shields the scalp, regulates temperature, and shapes our identity. Shiny, strong hair can boost confidence, so when it begins to thin, fall out, or lose its luster, it’s no surprise that we look for solutions. Yet, while the global market for hair growth supplements is booming, many products are long on promises and short on proof.

So, what really works? This article dives into the science behind the best hair growth supplements, based on current research. We also take a balanced look at Nutrafol®, a popular supplement getting a lot of attention, and break down essential lifestyle strategies to support healthier hair.

How Hair Grows

Hair grows from follicles embedded mostly within the middle layer of skin (the dermis). The hair strands that we see extending from our scalp are made up of dead, keratinized cells. It’s within the follicle—beneath the surface—that the real live action happens.

Each hair follicle houses the hair bulb, which is where new hair cells are produced. You may have noticed a hair bulb attached to a hair that you’ve plucked—it looks like a small white or greyish blob at the base of the strand. 

The follicle also has nerves that help you detect when someone touches your hair. It is also home to tiny muscles that can make hair stand on end—a leftover survival trait from our ancestors, which we recognize as the “goosebumps” stress response 1.

Each strand of hair goes through a cycle of growth (the anagen phase) followed by transition (the catagen phase), and then resting (the telogen phase) before finally shedding.

Every day, it’s normal to lose 100–200 hair strands, which are replaced through this natural cycle. Hair loss only becomes noticeable when something disrupts the balance of phases 1.

Hair Loss and Damage: Causes and Triggers

Hair loss—also known as alopecia—can be temporary or permanent, and it occurs for many reasons. Here are some of the most common types 2:

• Androgenic or “pattern” hair loss (androgenetic alopecia): The most common form, this type of hair loss is linked to genetics and hormones and can affect males and females. Hair loss typically begins at the temples with the hairline receding to form an “M” shape. This type of hair loss is also called male-pattern balding or female-pattern hair loss. 
• Telogen effluvium: This sudden temporary increase in hair shedding is often caused by stress.
• Alopecia areata: Believed to be autoimmune in origin, this form causes patchy hair loss and, in some cases, complete loss of scalp hair (alopecia totalis) or body hair (alopecia universalis). Recovery is unpredictable, with complete hair regrowth occurring in some people but not others 3.
• Tinea capitis: A fungal infection of the scalp that can result in broken hair patches that look like black dots on the scalp. If not treated, it can lead to scarring and permanent hair loss.
• Traction alopecia: Caused by tight hairstyles—like braids, ponytails, or weaves—that stress the follicles over time.
• Anagen effluvium: Often triggered by chemotherapy, it causes rapid, temporary loss during the growth phase of hair.

Hair can also accumulate gradual damage over time, making it look dull and coarse or breaking and falling out. This damage happens due to washing, brushing, and heat styling, but it especially results from 4: 

• Bleaching, which lightens hair by breaking down the natural pigment (melanin) inside  
• Permanent styling, like perming or straightening, which works by breaking and reshaping the hair’s internal bonds 

Stress Affects Hair Thinning

Stress may play a surprisingly strong role in hair thinning. In two studies, stress was linked to hair loss in 18% to 63% of women! Stress may be connected to hair loss in women even more than thyroid issues, which may be present in only 10% to 17% of women with hair loss 5 6. That’s a significant finding, especially given how often thyroid function is assumed to be the culprit behind hair loss. 

The Role of Nutrition in Healthy Hair

Hair loss is strongly associated with low dietary intake of 7: 

• Healthy fats
• Protein
• Vitamin D
• B12 
• Zinc
• Iron

In one study, 62% of women with hair loss had low vitamin D, 29% had low ferritin (a marker of iron stores), and 15% had abnormal zinc levels 8. 

Another study found that 80% of women with hair loss had low vitamin D, 75% had low B12, and 85% were vegetarians 5—a group at higher risk for lower B12, vitamin D, iron, iodine, calcium, and zinc 9.

Having an excess of certain vitamins (A and E) and minerals (selenium) may also be linked to hair loss 7 10.

9 Key Micronutrients and Their Role in Hair Health

Here are nine vitamins and minerals that can influence hair growth, positively or negatively, depending on the dose 11:

Practical Advice on Using Vitamins 

If you’re considering taking vitamins and minerals to support hair growth, the key is to proceed with caution. A general A–Z multivitamin is likely the most beneficial option. Higher doses of micronutrients should only be taken with a healthcare professional’s advice if they are certain you are deficient.

In most cases, I don’t recommend lab tests to assess vitamin status, as a balanced diet and supporting your gut health—which improves nutrient absorption—are usually enough to correct any deficiencies.

That said, vitamin D is an exception. It’s difficult to get enough through food alone, as the body primarily produces it when the skin is exposed to sunlight. I usually advise clients to get an inexpensive annual vitamin D blood test and use the results to guide their supplementation accordingly.

3 Other Promising Hair Supplements 

Beyond essential vitamins and minerals, several natural compounds show some potential in supporting hair growth and reducing hair loss—particularly in cases of androgenic alopecia. However, much of the research is still in its early days, and more robust studies are needed.

Probiotics

A randomized controlled trial (gold-standard type of study) involving 115 adults found that a mix of probiotic strains taken over 16 weeks helped reduce the amount of non-growing (telogen phase) hair and fine hairs, while increasing the proportion of actively growing, thicker hair. 

The improvement in hair thinning was most notable in people up to 37 years old with androgenic alopecia 14.

Marine Proteins

A research review of human clinical studies reported that marine proteins, which include collagen, are among the few natural supplements with some evidence supporting their role in improving hair volume and thickness. 

Proteins from sharks and mollusks are thought to work by strengthening the connective tissue around hair follicles, which may help reduce breakage and support overall hair health. Still, more high-quality studies are needed to confirm these benefits 15.

Saw Palmetto

Saw palmetto extract is believed to inhibit dihydrotestosterone (DHT), a hormone strongly linked to pattern hair loss. 

Clinical trials suggest that saw palmetto may provide modest benefits, particularly for those in the early stages of androgenic alopecia. Like other botanicals, results vary between individuals, and more rigorous trials are needed to establish dosage and effectiveness 15.

What About Nutrafol®?

Nutrafol® is one of the most well-known hair supplements and includes a complex blend of herbal extracts, vitamins, minerals, and other beneficial substances. Its increasing popularity is driven by marketing claims, influencer endorsements, and a growing body of clinical research.

What’s in It?

Nutrafol® formulas include ingredients like:

• Saw palmetto, which may block DHT
• Ashwagandha, said to reduce levels of the stress-related hormone, cortisol
• Hydrolyzed marine collagen to try to support hair structure and elasticity
• Curcumin, maca, and astaxanthin, which may act as antioxidants and adaptogens (Note: While curcumin is a popular ingredient in many hair supplements, I’ve found no evidence supporting its effectiveness for hair health or hair loss.)
• DHA omega-3s, resveratrol, and theanine, each with the potential to lower inflammation and oxidative stress
• Biotin, zinc, vitamin D, selenium, and vitamin B-12 (foundational hair nutrients)

What the Studies Say

Several randomized controlled trials sponsored by Nutrafol®y have found that the formulations:

• Improved hair growth and quality in men with thinning hair 16
• Increased the count of growing hairs and reduced shedding in perimenopausal, menopausal, and postmenopausal women 17
• Improved hair growth and hair quality, and also made women feel better about their hair 18

Even though Nutrafol® funded them, these trials were randomized and placebo-controlled—the gold standard in clinical research. An independent systematic review (methodical account) of these and other studies noted Nutrafol® as one of the products with reasonable evidence of a potential for reducing hair loss 19.

Downsides

• Cost: Nutrafol® is expensive—$88 per month, or $79 with a subscription.
• Results take time: It may take 3–6 months to see visible results.
• Over-supplementation risks: Contains nutrients like biotin, selenium and vitamin A that can be harmful in excess.

Nutrafol® also includes optional perks like access to a naturopathic coach, mineral testing, and a subscription to Headspace, which may help with stress—a known factor in hair loss.

My separate article on Nutrafol® goes into more detail, but before committing to this supplement, I recommend first focusing on improving the quality of your diet. A highly nutritious diet, combined with supportive lifestyle strategies, may be all you need to get your hair growth back on track—without resorting to expensive supplements.

You may also see similar results with less cost commitment by eating plenty of protein and increasing the nutrient-density of your diet, while possibly adding probiotics to help your gut absorb those nutrients.

The Importance of Protein for Hair Growth

Keratin, the main structural component of hair, is a type of protein made up of amino acids. It provides hair with its strength, flexibility, and resilience, so it’s clear why eating enough quality protein is essential for healthy locks.

Severe protein deficiency, as seen in conditions like kwashiorkor and marasmus, is rare in countries like the U.S. but can lead to thinning hair, brittleness, color fading, and even alopecia in those whose protein intake is chronically low 11.

Although such extreme deficiencies are uncommon, even modest shortfalls in protein may impact overall health and hair quality. This makes it all the more important to prioritize protein, especially as we age. It’s vital for maintaining muscle mass, supporting metabolism, and staying active and strong. Better, stronger hair may be a welcome side effect of consistently eating enough protein throughout the day.

As a general guideline, I suggest my clients aim for around 30 grams of protein at each meal, starting with breakfast, to support both overall health and hair quality.

5 Proven Habits that Support Hair Health

Alongside a healthy diet, and before considering supplements, it’s worth looking at habits that influence hair from the inside out:

1. Stress Management

Since stress is a major trigger of hair loss—linked to as many as 63% of cases—managing it through better sleep, therapy, and relaxation techniques is key for hair growth 5 6 7.

Many of my clients find the following strategies particularly effective:

• Improving sleep hygiene to get longer, more restorative rest. Establishing a regular bedtime routine and limiting screens before bed can make a big difference.
• Using meditation and mindfulness practices to improve stress resilience. If you’re not sure where to start, the Headspace app is a useful, beginner-friendly tool.
• Adopting a regular exercise regimen that includes aerobic training (to maintain or build VO₂ max) and more de-stressing activities like yoga or tai chi, if they suit you.
• Spending time in nature and taking breaks from built-up or urban environments.

2. Minimizing Harsh Hair Chemicals

As I noted earlier, bleaching, perming, and straightening your hair can significantly weaken it over time. One study found that hair dye and other harsh chemicals were the top factors in about 53% of women with hair loss 6.

Adopting a lower-maintenance hairstyle or switching to more natural hair products may help. Talk to your hairdresser or a trichologist (hair specialist) about gentler options that may leave your hair looking healthier in the long run.

It’s also a good idea to get a trim every few weeks to get rid of dry or split ends and keep your hair in better condition overall.

3. Addressing Underlying Conditions

Hair problems can sometimes be a sign of deeper health issues. For example, infections like COVID-19, chickenpox, and HIV have been linked to hair loss. Chronic medical conditions such as diabetes, polycystic ovary syndrome (PCOS), heart disease, and autoimmune disorders—especially thyroid-related ones—are also commonly cited contributors 7 10 20.

That said, these conditions may not be as prominent a factor as you’d expect. For instance, in studies of people with hair loss, less than 18% were found to have thyroid issues 6 8.

Inflammation has also been associated with hair thinning. What can you do about inflammation? Support your gut. A healthy gut supports nutrient absorption and immune regulation, both critical for reducing inflammation and promoting healthy follicle function 21. My Gut Reset Guide is a comprehensive resource for improving gut health, reducing inflammation, and improving your overall health—including your hair, skin, and nails.

It’s also worth noting that certain medications, such as beta-blockers and statins, and low-quality or contaminated supplements have been linked to hair loss 7. If hair loss is a concern, it’s a good idea to review your current medications and supplements with a healthcare professional.

Finally, lifestyle habits like smoking and heavy alcohol use are strongly associated with hair thinning, not to mention a wide range of other health issues 10. In general, it’s best to avoid both.

4. Red Light Therapy 

There are other interventions worth mentioning when it comes to improving hair health and hair loss. The first is red light therapy (RLT), which may help treat androgenic alopecia and has growing clinical support. 

Several meta-analyses (studies of studies) have shown that RLT can improve hair thickness after around four months of consistent use. RLT in the 630–660 nm range, and particularly when combined with blue light, seems to be the most effective for improving hair health 22 23 24 25. 

In a newer randomized controlled trial on women with androgenic alopecia, 25 minutes of RLT (655 nm) on their scalp every other day for 16 weeks increased hair growth by 37% compared to the placebo group 26.  

The FDA has cleared certain LED caps for use in red light therapy, but individual effectiveness may depend on the specific light wavelengths and usage 27. 

5. Scalp Massage

A lower-tech but promising method is scalp massage. A 2016 clinical trial found that daily 4-minute scalp massages increased hair thickness, possibly by physically stimulating the scalp and activating genes involved in hair growth 28.

Meanwhile, a survey found that nearly 7 in 10 participants reported less shedding and some regrowth after regularly massaging their scalp 29. However, the evidence is still limited and based mostly on small or uncontrolled studies, so results should be interpreted with caution.

What Are the Best Hair Growth Supplements? Let’s Summarize

If you’re keen to get started on a supplement regimen to help your hair, here’s a quick overview:

Although many supplements promise rapid results, sustainable hair growth is usually the result of consistent, long-term healthy habits. These include:

• Eating a nutrient-rich diet—especially one that supports gut health
• Managing stress
• Avoiding harsh hair styling practices
• Reviewing medications and underlying health conditions
• Maintaining a generally healthy lifestyle

Foundational Strategies for Hair Growth

Hair loss can be incredibly frustrating, especially when you can’t find a solution. Fortunately, foundational strategies for hair growth, like stress reduction and a nutrient-rich diet, can work wonders for healthy hair. Testing for deficiencies or underlying conditions may also help tailor a more effective approach—but for most people, these foundational strategies are all that is needed. If you’re experiencing significant or sudden hair loss, always consult a healthcare professional.

You can also reach out to us at the Ruscio Institute for Functional Health for a full assessment of your underlying health, including gut health, which we often find plays a key role in hair quality and regrowth.

The Ruscio Institute has also developed a range of high-quality formulations to help our clients and audience, some of which may be relevant to hair health. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you. The information on DrRuscio.com is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment.