Overview

The immune system is complex, and there is a lot of research on how different nutrients impact it. Before you buy any supplements, please make sure you are already prioritizing covering the basics, including eating healthy, sleep, hydration, and exercise. No amount of immune-boosting supplements or superfoods will make up for the basics you need to keep your immune system running effectively. If you have these basics in place, you may want to consider additional supplements to boost your immune system.

This episode is an overview of the risks, benefits, safety, and evidence available on the ability of many vitamins, herbs, and supplements to boost your immune system during pregnancy. I could easily do an entire episode on each of the immune-boosting supplements covered here, including folate and folic acid, vitamins A, C, D, E, zinc, selenium, antioxidants, glutathione, PQQ, herbal immune support, echinacea, elderberry, probiotics, mushrooms, and choline. As always, please talk to your doctor or midwife about any supplements you consider. That includes any herbs or over-the-counter vitamins or supplements.

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Article and Resources

If you have not heard the episode or read the article on supporting your immune system, I encourage you to start there. That episode covered the basics you must have in place to support your immune system. No amount of immune-boosting supplements or tactics will make up for those basics needed to keep your immune system running effectively.

Recommended Daily Allowance, Adequate Intake, and Tolerable Upper Intake Level

When discussing essential vitamins and nutrients, it is important to look at the amounts you should be getting during pregnancy to determine whether you meet those values with your diet and any additional supplements.

Dietary Reference Intake is the general term for the amounts of vitamins and nutrients to plan and assess the nutrient intakes of healthy people. These values vary by age and gender and if you are pregnant or breastfeeding. The daily value percentage on the back of product labels uses the dietary reference intake figures.

• Recommended Dietary Allowance (RDA): average daily intake level sufficient to meet the nutrient requirements of nearly all (97%-98%) healthy people. 
• Adequate Intake (AI): established when evidence is insufficient to develop an RDA and is set at a level assumed to ensure nutritional adequacy. 
• Tolerable Upper Intake Level (UL): maximum daily intake unlikely to cause adverse health effects 

Typically, you want to reach the RDA or the AI if an RDA is not established. Plus, make sure you are under the UL. The quantity of vitamins and supplements is often listed as micrograms (mg or mcg), milligrams (mg), or grams (g). One gram is equal to 1,000 milligrams or 1,000,000 micrograms. Different nutrients are measured in different units.

Prenatal Vitamin

Combined with a healthy diet, your prenatal vitamin should provide all the essential vitamins and nutrients you and your baby need. Before you consider additional supplements, make sure you are taking a high-quality prenatal vitamin. You have many choices to find a vitamin that is the right fit for you, and they vary widely in the ingredients they use and how they are formulated. The Zahler +DHA is my #1 choice because of the high quality of the ingredients. You may be better off improving your prenatal vitamin rather than spending additional money on other vitamins.

Folic Acid

The first thing I look for in a prenatal vitamin is folate rather than folic acid. The two most active forms of folate are methylfolate or folinic acid. You may see this listed on the label as “folate,” “Quatrefolic,” “methyltetrahydrofolic,” or “folinic acid.” This is more expensive to produce than folic acid, which is a big reason you don’t see this on every prenatal vitamin. For more details on folate vs. folic acid, visit this episode.

There is some evidence that high folic acid may reduce natural killer cells in mice. During pregnancy, you have an increased need for folate. This level of this ingredient is one of the key differences between a prenatal vitamin and a multivitamin. It would take a lot of testing to determine whether you are among the estimated 50% or more of the population who have trouble with unmetabolized folic acid. This animal study showing how it can affect your immune system may be another reason to opt for a prenatal vitamin with the active form of folate. This study was done on mice, not expecting mothers, and it is not a perfect model, but it still has some application here. Natural killer cells are an essential component of your immune system and your ability to fight infection. Even if your prenatal vitamin has the active form of folate, folic acid is in almost any processed food with carbohydrates, like bread or cereals. This is another reason to avoid processed foods as much as possible and focus on whole foods.

Vitamin D

One of the most critical things vitamin D does is aid in absorbing other essential nutrients like calcium, iron, magnesium, phosphate, and zinc. Vitamin D also regulates immune function, cell growth, and neuromuscular function. This vitamin is unique because we can make it from exposure to sunlight. This is a complex process, but a simplified summary is that when UVB rays hit the surface of your skin, your body uses photosynthesis to start processing it. Vitamin D from sun exposure, food, and supplements is biologically inert. To be activated, it must undergo two hydroxylations in the body. Vitamin D is sometimes referred to as a hormone because its activated forms are hormones.

We get the majority of our vitamin D from the sun. However, the amount of vitamin D from the sun varies depending on where you live, the time of year, the time of day, how much skin is exposed, your skin, etc. If you live near the equator, you get more sunlight. If you live above 37 degrees latitude in the United States, you probably aren’t getting enough vitamin D from sunlight in winter.  Thirty-seven degrees latitude is about if you cut California in half at San Francisco and went across the northern borders of Arizona, New Mexico, and Texas to Philadelphia on the east coast.

Vitamin D is a fat-soluble vitamin. This means it is dissolved in fat and stored in fatty tissue, so your body can store it and use it as needed. We build up a higher vitamin D store in the summer months that your body can access in the winter. If you are not getting enough sun exposure, you need to make sure you get adequate vitamin D from your diet or a supplement.

Vitamin D deficiency is common, especially in people with darker skin. A study that examined vitamin D deficiency during pregnancy found ninety-seven percent of African-Americans, 81% of Hispanics, and 67% of Caucasians were deficient. If you need additional reasons to make sure you are getting adequate vitamin D, there are plenty. Research shows vitamin D deficiency is a risk factor for preeclampsia. Evidence also indicates an association between vitamin D deficiency and increased odds of primary cesarean section. A study looked at how maternal vitamin D deficiency could affect a baby later in life and was associated with impaired lung development in 6-year-olds, neurocognitive difficulties at age 10, increased risk of eating disorders in adolescence, and lower peak bone mass at 20 years.

The only way to test for vitamin D deficiency is with a blood test that measures the amount of serum levels of 25-hydroxy vitamin D (25[OH]D). If you are concerned about vitamin D levels, please talk to your doctor or midwife about getting tested.

There has been some recent research about vitamin D deficiency and COVID-19. In one study, patients deficient in vitamin D were at a higher risk for COVID-19. Several meta-analyses have shown a protective effect of vitamin D on respiratory infections. Colds, flu, and COVID-19 are all respiratory infections. A Cochrane Review found that supplementing pregnant women with vitamin D probably reduces the risk of preeclampsia, gestational diabetes, and low birth weight and may reduce the risk of severe postpartum hemorrhage. There are many reasons to ensure you get enough vitamin D during pregnancy.

Getting enough vitamin D solely from sun exposure and your diet is challenging. The RDA for pregnancy is 600 IU (international units) per day. Most prenatal vitamins contain 400 IU. If you think you are not getting adequate vitamin D, talk to your doctor or midwife about supplementing. You cannot get too much vitamin D from the sun.  That doesn’t mean you cannot get a sunburn. You could take too much vitamin D from supplements, but the toxicity threshold is over 10,000 IU per day.

Relationship Between Immune Function and Antioxidants

Free radicals are a natural byproduct of the biochemical reactions that happen in your body. These are molecules or atoms that are unstable because they have an unpaired electron, and they can steal an electron and damage lipids, proteins, RNA, and DNA. Antioxidants balance out free radicals and can protect or reverse the damage caused. When you have an imbalance between free radicals and antioxidants in your body, it causes oxidative stress. This stress can cause chronic inflammation and affect your immune system.

You get many antioxidants from your diet. Plants are much higher in antioxidants than animal-derived products. Some foods with the highest antioxidants include pomegranate juice, blueberries, walnuts, pecans, cranberries, and artichokes. Herbs and spices like allspice, mint, and cloves have antioxidants. Chocolate is also a source of antioxidants, with darker chocolate having a higher content than milk chocolate. A study that analyzed the total antioxidant content of over 3,100 foods found that the antioxidant content in human breast milk is comparable to that in pomegranate juice, strawberries, and coffee. Plus, on average, it is higher than the antioxidant content observed in commercially available infant formulas—one of the many reasons to breastfeed your baby. In addition to foods, many vitamins have antioxidative properties, including vitamins A, C, and E, as well as zinc and selenium.

Vitamin A

Vitamin A is involved in immune function. Since the COVID-19 pandemic, there has been more focus on using this as immune support. High doses of vitamin A are not recommended during pregnancy because there is some evidence of abnormalities in babies whose mothers consumed high amounts of vitamin A. These include abnormalities in the urinary tract, miscarriage, or cardiac malformations. For these reasons, vitamin A supplementation is not recommended during pregnancy.

The amount of vitamin A in your prenatal should be well within the suggested upper limit and below the RDA. The Recommended Daily Allowance for vitamin A is given as retinol activity equivalents (RAE) to account for the differences in how your body converts different types of vitamin A into retinol. The RDA for vitamin A is 770 mcg RAE during pregnancy.

1 mcg RAE =

• 1 mcg retinol
• 2 mcg supplemental beta-carotene
• 12 mcg dietary beta-carotene
• 24 mcg dietary alpha-carotene or beta-cryptoxanthin.

For more in-depth information on vitamin A during pregnancy, see this article.

Rather than spending a lot of time analyzing quantities of ingredients on a vitamin label, I would put energy into finding a company that you know makes high-quality vitamins. When you find a company you trust, it takes some of the work to look into every ingredient. You can also check out labdooor.com, an independent third-party company that tests vitamins and supplements and rates them on purity, label accuracy, and quality.

Vitamin C

Vitamin C is a powerful antioxidant. A Cochrane Review that examined studies on vitamin C supplementation during pregnancy found mixed results. Some studies showed a decreased risk for placental abruption and reduced risk for preterm and term rupture of membranes. Overall, more research is needed to understand the possible role of vitamin C in placental abruption and PROM. The researchers state there was no convincing evidence that vitamin C supplementation results in other significant benefits or harms. This study did not look at vitamin C’s role in immune function.

Vitamin C helps your immune system by supporting cellular function. Plus, if you have an infection, your vitamin C levels are impacted due to increased inflammation and metabolic requirements.

One study showed vitamin C supplementation reduced hospitalizations. Additional vitamin C may have more of an application in regions where fresh fruits and vegetables are not widely available. The deficiency rates are lower in high-income countries where diets contain more produce.

While obviously smoking is unhealthy, especially during pregnancy, smokers do have increased vitamin C requirements. A study found that additional vitamin C supplementation in pregnant mothers who smoked improved infant lung function. If you are pregnant and smoke cigarettes and have difficulty quitting, please talk to your doctor or midwife. There are well-documented adverse effects traced directly to cigarette smoking during pregnancy.

There is a lot of evidence that vitamin C supplementation may help reduce colds for specific populations. For example, studies with marathon runners or people who live in extreme weather conditions. Other studies show that vitamin C can reduce the severity of a cold. Dosage is important, and across different studies, it varies greatly. We do not have definitive evidence stating what vitamin C supplementation level is required to effectively prevent or treat a cold, especially in pregnant women.

Your body does not absorb 100% of the vitamin C you take in. Typically, you absorb 70-90% up to one gram. Over that amount, you absorb less than 50%. Your body excretes any excess unabsorbed vitamin C in your urine. Some side effects can include stomach cramping, bloating, nausea, and other digestive issues. The tolerable upper intake level for pregnant women is 2,000 mg per day. This is way above the RDA of 85 mg.

Vitamin E

Vitamin E is a fat-soluble vitamin and another powerful antioxidant. A Cochrane Review on vitamin E supplementation in pregnancy examined the evidence and found no convincing evidence that vitamin E supplementation in combination with other supplements results in other important benefits or harms. The tolerable upper intake level for pregnant women is 1,000 mg per day. This is much higher than the RDA of 15 mg. A small study found that high maternal vitamin E by diet and supplements is associated with an increased risk of congenital heart defects in offspring. Vitamin E deficiency is rare; you will likely get adequate vitamin E from your diet and a prenatal vitamin.

Zinc

Zinc is an essential mineral that plays a role in immune function, among many other aspects of cellular metabolism and healthy growth and development during pregnancy. The highest source of zinc in foods is in oysters, followed by meats and beans. Zinc in animal products is more bioavailable than from plant sources. Zinc is critical for your immune function. A downside to taking too much zinc is that too much zinc can negatively impact your immune function. The tolerable upper intake level during pregnancy is 40 mg.

A Cochrane Review examined 21 randomized controlled trials on zinc supplementation during pregnancy. Some trials showed a 14% relative reduction in preterm birth for zinc compared with placebo. These trials primarily involved women of low income, which has some relevance in high perinatal mortality. There was no convincing evidence that zinc supplementation during pregnancy results in other useful and important benefits.

Another review that examined zinc for use with a cold found that when taken in syrup or lozenge form within 24 hours of the onset of symptoms, it can reduce the length and severity of colds. All of these studies were in high-income countries. A review that compared the efficacy of zinc acetate lozenges with zinc gluconate lozenges in common cold treatment found them comparable. The researchers also found no evidence that zinc doses over 100 mg/day might lead to greater efficacy in treating the common cold. 

Selenium

Selenium is a mineral with antioxidant activity and plays a role in protecting it from oxidative damage and infection. The amount of selenium in plants and meat depends mainly on soil bioavailability, which varies by region. In the US, selenium deficiency is rare. Foods highest in selenium include seafood, organ meats, and Brazil nuts. Selenium is also in bread, grains, meat, and eggs. If you live in the United States or another high-income country, you will likely get adequate selenium from your diet and a prenatal vitamin.

Antioxidant Supplements

You can get supplements beyond vitamins C and E that are potent antioxidants. If you consider using any of these during pregnancy, please run it by your doctor or midwife first.

Glutathione and PQQ

Glutathione is a master antioxidant produced in your body or taken as a supplement. Glutathione supplementation may not be recommended during pregnancy because of its detox effects and the ability to bind to heavy metals.

PQQ stands for pyrroloquinoline quinone, also called methoxatin. PQQ is a vitamin-like compound in soil and various foods, including spinach, kiwi, soybeans, and human breast milk. Dr. Ben Lynch prefers PQQ over glutathione during pregnancy. Unfortunately, there is less research available on PQQ. One study of PQQ supplementation in obese mice during pregnancy and lactation found that it helped protect against inflammation. We need more research to know whether there are benefits to supplementing with this during pregnancy. Please talk to your doctor or midwife if you consider a supplemental antioxidant during pregnancy.

Herbal Immune Support

The use of herbs and supplements during pregnancy has increased in recent decades. As we learn more about risks associated with common medicines or an abundance of concern over our baby’s health, you may look to more natural remedies. Even if you take an herbal supplement, please run it by your doctor or midwife. A survey of herb and supplement use among pregnant women in the US found as many as 25% do not disclose the use of herbs and supplements to their physicians.

Echinacea

Echinacea is a group of flowering plants native to North America. Echinacea is widely used in the US and Europe to prevent and treat colds. Supplements containing Echinacea can differ in composition, depending on the plant’s part, extraction and manufacturing methods, and other components. A study on mice used different types of Echinacea and measured the changes in immune activity. The three species they included were Echinacea Angustifolia, Echinacea pallida, and Echinacea purpurea. They found two, Echinacea Angustifolia or Echinacea pallida, may have more anti-inflammatory potential.

A review examined the body of evidence on the effectiveness of Echinacea. The review included 24 double-blind trials with 4,631 participants. The review found that echinacea products have not been shown to provide benefits for treating colds. They go on to state that there may be a weak benefit from some echinaceaproducts. The results of individual prophylaxis trials consistently show positive (if non-significant) trends, although potential effects are of questionable clinical relevance.

Elderberry

Elderberry is extracted from the berries of the sambucas tree. It is often sold in syrup, gummy, or lozenge and marketed to prevent or relieve cold or flu symptoms. There is some evidence showing that elderberry may be useful for reducing the occurrence of colds or the severity of symptoms. There is a lack of evidence available on the use of elderberry during pregnancy. This evaluated the use of elderberry for travelers and found it to be protective. This brings up a great point. Using anything that you think will boost your immune system may be more applicable in acute scenarios than everyday use. Your risk of exposure to an illness is higher traveling on an international flight than staying close to home and not encountering many people.

Probiotic

Research shows that probiotics can influence your immune function. Your gut houses many of your immune cells. Probiotic-rich foods include fermented foods like sauerkraut, kimchi, or kombucha. Yogurt and kefir are high in probiotics. In addition to having probiotic-rich foods in your diet, you can also take a probiotic supplement. There is even some evidence that taking a probiotic can reduce your chances of getting group B strep or help with constipation.

Some common side effects of probiotics are digestive issues like gas, bloating, or constipation. These symptoms tend to go away in a few weeks. One way to limit the side effects is to start with a lower dose of probiotics and gradually increase to the suggested daily amount. Many supplements will include instructions to do this on the label.

Most probiotic supplements combine different species in the same supplement. These are known as broad-spectrum probiotics or multi-probiotics.  The most common species you will see on the label for a probiotic are Lactobacillus and Bifidobacterium. If you are considering a probiotic specifically for your immune system, bifidobacterium interacts with immune cells and modulates specific pathways in the innate and adaptive immune processes. For more information on probiotics during pregnancy, check out this episode.

Mushrooms

Mushrooms have been used medicinally for thousands of years. The ingredient contained in some mushrooms relevant to the immune system is β-glucans. These are polysaccharides responsible for anti-cancer, immunomodulating, anticholesterolemic, antioxidant, and neuroprotective activities. There are many mechanisms by which mushrooms affect immunity. Some upregulate genes, which lead to anti-inflammatory and anti-cancer cytokines, can activate immune cells. For a deep dive into mushrooms’ anti-inflammatory and immunomodulating properties, see this article. There is even evidence that mushrooms can inhibit the growth and metastasis of cancer cells. A study showed that consuming shitake mushrooms daily improved immunity. There is a lot of research underway to identify and isolate the molecules from mushrooms that could treat various ailments.

You can consume medicinal mushrooms in teas, capsules, powders, or dried. You can also get products specifically marketed to boost your immunity. Companies like Four Sigmatic have made supplementing with mushrooms the mainstream. These typically contain mushrooms like reishi, lion’s mane, chaga, shitake, maitake, turkey tail, and cordyceps. There is no research on psilocybin mushrooms during pregnancy, and those are not the mushrooms we are discussing here. We are talking specifically about immune-boosting mushrooms. I found no evidence suggesting any of these supplements would be dangerous to consume during pregnancy. I also found no evidence demonstrating complete safety. Like many of the supplements discussed here, there is a difference between taking something occasionally and incorporating it into your long-term daily routine. You can always ask your doctor or midwife for their thoughts to be safe. Hopefully, we will have some studies on the effects of medicinal mushrooms on the pregnant population in the future.

Choline

Choline is a nutrient needed for many functions, including forming the membranes surrounding your body’s cells. Your developing baby needs choline for their brain and spinal cord. You naturally produce a small amount of this in your liver but need additional choline from your diet or a supplement to meet your requirements. The highest choline sources are liver, egg yolk, beef, soybeans, chicken, and fish.

Many prenatal vitamins do not include choline. In 2017, the American Medical Association supported adding it to prenatal vitamins. The adequate intake amount set by the Food and Nutrition Board of the Institute of Medicine is 450 mg. You need even more choline (550 mg) per day when breastfeeding. Typically, the higher quality prenatal vitamins that include choline include 55 mg. Plus, you are making some choline and getting some from your diet. If you supplement with additional choline, the tolerable upper intake limit during pregnancy is 3,500 mg daily, considerably higher than the adequate intake. This upper intake level is about the point where you start to see side effects of taking too much choline, like a fishy body odor, excessive sweating and salivation, hypotension, and liver toxicity.

Choline is one of many nutrients that, in some way, support your immune system. All your immune cells need membranes, which you need choline to produce. Choline was only recognized as an essential nutrient in 1998, and we have limited research on it. A study on COVID-19 and fetal brain development had interesting results. They found that higher choline levels may protect fetal development and support early behavioral development even if the mother contracts a viral infection in early gestation. This was a small study with less than 100 participants. As more research is available on choline supplementation during pregnancy, I hope to share more evidence on the benefits or risks associated with supplementing with this nutrient. I did not find any evidence showing the risks of taking choline during pregnancy, provided you are staying within limits set by the Food and Nutrition Board.

The Placebo Effect

In the episode on supporting your immune system, I shared my go-to remedy anytime I feel like I am coming down with a cold or illness. This supplement has a lot of herbal ingredients, including Echinacea and elderberry. There is no double-blind placebo-controlled study showing this product is 100% effective. I only have my own experience with it, and I must acknowledge that some of my positive experiences could be due to the placebo effect.

A placebo is a sham treatment or a sugar or cellulose pill with no active ingredient. Many trials use a placebo in half of the participants to help measure the efficacy of the treatment. The placebo effect describes a beneficial effect produced by a placebo drug or treatment, which cannot be attributed to the placebo’s properties. It must, therefore, be due to the patient’s belief in that treatment. Every study that uses a placebo will have some participants taking a placebo and experiencing an improvement.

I believe that this immune supplement helps me fight off a cold. That is the benefit. I do not feel any risk of taking this for my situation, so the downside is zero. Why not take it? If you have a ritual or a food or supplement that you swear helps boost your immune system, by all means, utilize it.

How to Prioritize What Supplements to Take

The immune system is complex, and we have a long way to go until we thoroughly understand precisely how it functions and how different supplements impact it. Before you buy any supplements, please make sure you prioritize the basics. The episode on supporting your immune system covers the basics, including eating healthy, sleep, hydration, and exercise.

You should take a high-quality prenatal vitamin. Between an excellent prenatal vitamin and a healthy diet, you will likely cover your bases for the vitamins and nutrients you and your baby need. When adding other vitamins, please check if they are included in your prenatal vitamin first and consider whether you eat foods high in those nutrients. If you have concerns about vitamin deficiency, please ask your doctor or midwife about testing.

If you feel amazing, you may not need additional supplements. You also do not need to be taking immune-boosting supplements every day. You may take them occasionally when you aren’t feeling great or every other day. If you pay attention to how you feel, your body will let you know if a supplement works for you. If you start taking something and don’t feel great, stop. As always, please run all supplements you plan to take by your doctor or midwife and ask them any questions regarding dose and safety.

Thank you to the amazing companies that have supported this episode.