Immunoglobulins Explained: A Beginner’s Guide

• What Immunoglobulins Are|
• How They Support Gut Health|
• How to Get Immunoglobulins|

You’ve likely heard of antibodies—especially in discussions about immunity and disease. Antibodies are specific immunoglobulins—large, Y-shaped proteins that recognize and bind to foreign substances in the body to shut them down. But how do these crucial components of your body’s defense system function, and what do they have to do with gut health? 

In this guide, I’ll demystify immunoglobulins, explaining their fundamental role in the body, their benefits for gut health, and how you can support your body’s stores of them.

What Are Immunoglobulins?

Immunoglobulins (Ig for short) are Y-shaped proteins your immune system makes to spot and stop invaders like bacteria and viruses. You can think of them as specialized security guards, each trained to recognize a specific threat and alert the body to take action.

Once released, each specific immunoglobulin is an antibody. Your body can make millions of different antibodies, each with a unique “lock” that fits a specific “key” on a pathogen (germ) or toxin, allowing it to recognize and target that particular threat 1.

All antibodies fall under one of the five classes of immunoglobulins—IgG, IgA, IgM, IgE, and IgD—each of which plays a slightly different role in your immune response. Each specializes in a different job, from long-term memory to guarding entry points like your mouth and gut. The details get complex, but the big takeaway is that your immune system has multiple layers of protection working together.

How Immunoglobulins Work Within Immunity (For the Curious)

Your immune system protects you through two main layers of defense: innate immunity, which acts immediately, and adaptive immunity, which develops a targeted, long-lasting response 2.

• Innate Immunity acts as your body’s first line of defense, using barriers like skin, mucous, and secretions to block invaders. Cells such as phagocytes, natural killer cells, and mast cells, along with signaling molecules like cytokines and complement proteins, help detect and destroy pathogens quickly—but this response is broad and doesn’t provide long-term memory.
• Adaptive Immunity provides a targeted, lasting defense. B cells produce antibodies, and T cells help or directly kill infected cells. When certain cells show them pieces of germs called antigens, specific B cells and T cells multiply and form memory cells, allowing your body to respond faster and stronger if the same pathogen appears again. The part of your adaptive immune system that works from within your body’s fluids is called humoral immunity.

Immunoglobulins are part of adaptive immunity, acting as key players in humoral immunity. When they become antibodies and encounter germs or toxins, immunoglobulins help your body respond in three main ways. They can 1:

1. Neutralize: Block pathogens from infecting cells, or deactivate toxins.
2. Opsonize: Tag pathogens so immune cells like macrophages can find and destroy them.
3. Activate Complement: Set off a chain reaction of proteins that can directly kill pathogens or boost other immune defenses. This coordinated action ensures that once a threat is recognized, your immune system responds quickly and effectively.

The Role of B Cells

B cells make immunoglobulins. B cells develop in the bone marrow—any that might attack the body are removed to prevent autoimmunity. Once mature, B cells travel to lymphoid organs (such as lymph nodes and the spleen), where they wait to encounter antigens—the molecules on germs or toxins that signal a threat.

When a B cell recognizes an antigen, it can:

1. Become a plasma cell, producing large amounts of immunoglobulins to neutralize germs or mark them for destruction.
2. Become a memory cell that quickly produces the same immunoglobulins if the same germ appears later.

In addition, B cells help coordinate other immune cells by releasing signaling molecules. 

And in specialized parts of lymph nodes called germinal centers, B cells can also improve the function of immunoglobulins through a process called class switching. This allows B cells to make all different types—IgM, IgG, IgA, IgE, and IgD—so the body can mount a strong, lasting defense against infections.

How Immunoglobulins Support Gut Health

So far, we’ve been talking about big-picture immunity. But here’s where it gets really interesting: Immunoglobulins aren’t just about fighting colds—they also have direct effects on your gut. 

How? Research by an immunoglobulin supplement company suggests that immunoglobulins may support gut health in several important ways, including 3:

• Strengthening the gut lining: Immunoglobulins may help reduce “leaky gut,” where the gut wall becomes too porous and lets harmful substances through.
• Calming inflammation: Immunoglobulins may lower immune signals that trigger gut irritation and damage, helping the gut heal.
• Working where needed: Unlike many proteins that are broken down early in digestion, supplements called serum-derived bovine immunoglobulins (SBIs) may make it all the way to the colon, where they may bind and neutralize gut irritants.
• Encouraging good bacteria: Immunoglobulins may support the growth of helpful gut microbes, allowing them to make substances that keep the gut lining strong and inflammation low.

In the clinic, we often start with proven gut therapies like diet changes, healthy habits, and probiotics, which focus on balancing bacteria and fungi in the gut. But for patients who don’t fully improve with these therapies, we’ll recommend supplementing with immunoglobulins as a powerful next step. 

How to Get Immunoglobulins

Your body makes its own immunoglobulins, but you can also get extra support from certain foods and supplements.

Bovine Colostrum

One way to get supplemental immunoglobulins is through bovine colostrum—the first milk cows produce after giving birth. You can find it in powder form, as pills, or as liquid. It’s packed with antibodies (IgA, IgM, and especially IgG), growth factors, and other compounds. 

Even though these antibodies are made by cows, many are close enough to human ones that they may still provide protection, especially for the gut. For example:

• A meta-analysis (high-quality study) of 10 studies found that bovine colostrum supplements can reduce intestinal permeability, as measured by urinary sugar tests, though it doesn’t affect plasma levels of I-FABP, a marker of gut cell damage 4.
• A systematic (methodical) review of 22 human studies found that bovine colostrum may be a generally safe supplement for improving diarrhea and some GI inflammation 5. 

The upshot: Though optimal doses are still unknown, human studies suggest bovine colostrum is safe and may help support gut health and reduce diarrhea.

Serum-Derived Bovine Immunoglobulins

Another way to get immunoglobulins is by taking serum-derived bovine immunoglobulin (SBI). SBI is isolated from cow serum (the yellowish liquid part of blood that’s rich in important substances but can’t clot) and purified as a concentration of mainly IgG. SBI has been studied as a way to ease gut problems in people with IBS-D (diarrhea-predominant IBS) and inflammatory bowel disease (IBD). For example:

• In a randomized controlled trial—the gold-standard type of human experiment—people taking 10 g/day of SBI reported fewer days with abdominal pain, bloating, diarrhea, gas, and urgency, and people taking 5 grams per day had reduced gas and feelings of incomplete evacuation 6.
• A review of patient records confirmed that SBI could safely improve symptoms in people with diarrhea-predominant or mixed-type IBS who hadn’t improved with other treatments 7.
• Another study found that 10 grams a day of SBI for 8 weeks reduced stool frequency and made bowel movements easier, though other bowel functions didn’t change much 8.
• A patient survey (weak evidence) of IBS and IBD patients who took 5–20 grams of SBI a day for more or less than six months (with or without other medications) showed that the percentage of those with normal stool frequency rose from 35% to 91%, while their average number of daily stools dropped from 6.5 to 2.6. Most said SBI helped them manage their condition (67%) and return to daily activities (59%) 9.

The upshot: SBI seems to safely reduce diarrhea, bloating, and bowel urgency while supporting better gut function and quality of life in people with IBS and IBD.

Dosing

Our Intestinal Support Formula is an SBI that provides advanced immunoglobulin support that mirrors those naturally found in the human gut, helping target gut health effectively. It’s made with safety and purity in mind—free from common allergens like wheat, soy, casein, eggs, nuts, shellfish, and lactose, and without gluten or artificial flavors or colors.

For our clients whose gut symptoms persist despite following an anti-inflammatory diet and taking probiotics, we recommend taking our Intestinal Support Formula as follows: 

• 5–10 grams (2 scoops) per day, with or without food 

Typically, we’ll use it for a minimum of 2–3 months, and if it seems to be helpful, it’s safe to stay on it longer. Many of our clients use it for 6–12 months. 

Risks/Safety Concerns

Immunoglobulin supplements are usually safe for most people when used as directed 10 11 12 13. That said, like with any supplement, it’s important to be aware of possible risks and precautions related to bovine colostrum or SBIs, including:

• Medication Interactions: Those on immunosuppressants or autoimmune medications should consult a doctor about potential immune effects.

Quality and Purity: Contamination is possible if sourcing is poor; choose reputable brands with third-party testing. If you have any health conditions, are pregnant or breastfeeding, or take medications, it’s important to check with your doctor before using immunoglobulin supplements. 

Getting personalized guidance helps you use them safely and get the most benefit for your gut and overall health. By understanding these considerations, you can make informed decisions about incorporating immunoglobulins into your health regimen, maximizing their benefits while minimizing potential risks.

Your Next Step in Immune Support

Immunoglobulins are far more than just disease-fighting proteins—they’re central players in how your body identifies, remembers, and responds to threats. By understanding their roles and how to support them, whether through your own immune system or carefully chosen supplements, you can take practical steps toward strengthening both gut health and overall immunity. 

If some personalized support would help get you on your way, we invite you to reach out to our team of clinicians at the Virtual Clinic.

The Ruscio Institute has developed a range of high-quality formulations to help our clients and audience. 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.