Can you boost your immune system? Will vitamin or mineral supplements help? What you need to know for healthy aging.

First, let’s take a minute to answer the first question in the headline. Can you boost your immune system? In a fascinating book, Immune, Philipp Dettmer, author and creator of a popular YouTube channel Kurzgesagt (German for In a Nutshell) says we’ve got it wrong when we talk about boosting the immune system. The immune system is a well-coordinated system. One that works in concert to fight pathogens that try to make us sick. Think of it like a beautifully choreographed dance or piece of music, where every move or note is well-timed to produce a harmonious effect. Change or “boost” one part, and the whole might be chaotic.

What is the immune system?

As this illustration shows, our immune system is comprised of a fast, quick-acting non-specific part (called the innate system) and a slower, specific part (adaptive system). The first or the innate system includes our body’s physical barrier to help stop bad things or pathogens from entering the body…our skin, our gut, epithelial cells that line all the body parts that are exposed to the outside…. eyes, nose, mouth, and the entire gastrointestinal tract. The innate system can help us identify the pathogen by signaling many cells, such as the complement system, phagocytic cells, neutrophils, macrophages, natural killer cells….and help to eliminate it. This system moves fast to identify and destroy threats, usually through inflammation, and then resolves the inflammation and repairs the damage caused by the pathogen.

The second part, the adaptive system, includes antigen-specific cells (T-cells and B-cells) and all the various subsets of these cells to coordinate the overall response and generate “memory” so that if we see the pathogen again, we can mount a quick and vigorous response. This immunological memory is the way vaccines work to provide protection from pathogens.

How does aging affect the immune system?

As we age, our immune system ages along with us. Scientists use the term immunosenscence to describe the changes (“senescence” literally means to grow old, the opposite of adolescence). And though the changes are gradual, and the system is less efficient than when we were younger, the changes aren’t the same for all of us.

Another term used to describe the aging immune system is “inflamm-aging; the theory that the innate immune system overtakes the adaptive system, leading to chronic inflammation, setting the stage for diseases associated with aging, including Alzheimer’s, cancer, frailty, and cardiovascular diseases.  

Remember that the immune system doesn’t work in isolation but is influenced by our environment including physical activity and optimal nutrition.

Are dietary supplements, like vitamin D or zinc the answer to strengthening our immune system?

Dietary supplements can help fill nutrient gaps or be used to treat deficiencies. In the research surrounding immune function and aging, very little attention is paid to nutrition. As one researcher put it, “this is surprising, given that the importance that nutrition plays in immune function is well established.” Deficiencies or suboptimal intakes of some nutrients negatively affect immune function and can decrease resistance to infections.

The keywords here are deficiencies or poor intakes; for those who eat a nutrient-rich diet, extra intake of vitamins or minerals will not “boost” your immune system.  About a dozen vitamins and minerals are key players in a healthy immune system, vitamin D and zinc get a lot of attention, especially as cures or treatments for COVID-19.

Many of your well-meaning friends might be touting these nutrients on their social media feeds with messages like, “taking loads of vitamin D is all that is needed to fight COVID,” or “stock up on vitamins and minerals, they are natural infection fighters, so you can’t take too much.” (Hemlock is a natural poison, so clearly you can take too much of a “natural” substance.)

Should you take Vitamin D?

You might think of bone health linked to vitamin D but it is also important in immunity. It helps modulate the immune system, making immune cells less inflammatory. Various groups, from the Institute of Medicine (IOM is a nonprofit organization and part of The National Academies that works outside the framework of government to provide evidence-based research and recommendations for public health and science policy), recommend that all adults aged 51 to 70 years get 600 IU (equal to 15 micrograms) a day and those over the age of 70 get 800 IU a day (20 micrograms). The Endocrine Society suggests adults need 1000 to 1500 IU to ensure adequate blood levels of the vitamin.

Older adults are at risk for insufficiency because the skin doesn’t make vitamin D from sunlight as efficiently with aging. Many adults turn to vitamin D supplements to get the needed vitamin D.

While there are many studies on the relationship of vitamin D and prevention of infection (like COVID-19), there is still no consensus that we need to load up on the vitamin, especially if you don’t know your blood level vitamin D. Adding to the confusion is the number of YouTube videos (many by medical professionals) who provide misinformation about vitamin D. In a recent paper, researchers reviewed 77 videos with thousands of views and found over three-quarters of them containing misleading content about vitamin D and COVID-19. And 58% of the videos stated that vitamin D can prevent or cure infections.

The Bottom Line

• If you have not had a vitamin D blood test, don’t self-diagnose a deficiency and start taking vitamin D.
• If you have had your blood levels of vitamin D measured by your doctor and she or he has recommended a supplement, continue to take the dose as recommended.
• If you take a multivitamin/mineral supplement you may be getting the recommended amount or slightly higher for vitamin D; multis formulated for “seniors” often contain 1000 IU of vitamin D. Don’t take any more than the Upper Limit of 4000 IU/day unless prescribed by a physician.
• It is hard to get enough vitamin D from food because the best food sources are fatty fish; think of salmon, tuna, sardines. We know eating fish is good for our health in many ways, so include a fish meal at least twice a week. Many foods are fortified with vitamin D with dairy milk being the best example (check the labels of plant-based milk to make sure your favorite includes vitamin D).

Should you take zinc?

We have no stores of zinc in the body, so it is needed in the diet every day. Zinc is better known for its role in inhibiting the common cold virus from sticking and replicating in the nose and throat. It can also stop the inflammation that contributes to the symptoms of a cold…runny nose and stuffy head. (However, zinc supplements will not prevent colds; when taken in the right dose at the first sign of a cold the length of the illness is reduced by about one day.)

When using it for warding off a cold, keep in mind the following:

• Timing and dose are important, try one zinc lozenge at the first sign of a cold and take it every 4 hours (most have 10 to 15 milligrams of zinc per dose but avoid those with high levels of zinc).
• More isn’t better, in fact, it can make things worse; nausea and vomiting can occur if you take too much, and it can leave a metal taste in your mouth.
• Avoid zinc nasal sprays…zinc sprays can change your sense of smell.
• Zinc can interfere with some prescription medications, like antibiotics and blood thinners, so always consider potential drug interactions.

The Bottom Line

• Zinc is important for a healthy immune system but there is no evidence at this time that it will boost immunity or protect against COVID-19.
• Too much zinc, which is easy to get in supplement form, can cause nausea and vomiting.
• The Upper Limit for zinc is 40 milligrams so keep that in mind if you use zinc lozenges.
• Aim for zinc-rich foods every day. Good choices are seafood (oysters, lobster, crab), beef, pork, poultry, baked beans, and fortified breakfast cereals.

Summary

Thank you for reading through this long post! Here’s my summary:

The immune system is a finely tuned system where all parts work together to maintain a defense but not be too aggressive. Over-reacting could tip the balance to auto-immune diseases. Food or supplements cannot boost immunity. Too much of a good thing can be a bad thing.

Eat a nutrient-rich dietary pattern, including fruits and veggies in any form that works for you (fresh, canned, frozen), beans, peas, and lentils, protein-rich foods, whole grain carbs, and healthy fats. And, fiber, don’t forget to consume dietary fiber to keep your gut microbiome happy! Much of immune system resides in our gut!

Chris Rosenbloom is a registered dietitian and nutrition professor emerita at Georgia State University. She is the co-author of Food & Fitness After 50 and blogs about optimal aging.

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