Many products on store shelves claim to boost or support immunity, but the concept of boosting immunity actually makes little sense scientifically. In fact, boosting the number of cells in your body — immune cells or others — is not necessarily a good thing. For example, athletes who engage in "blood doping" — pumping blood into their systems to boost their number of blood cells and enhance their performance — run the risk of strokes. Attempting to boost the cells of your immune system is especially complicated because there are so many different kinds of cells in the immune system that respond to so many different microbes in so many ways. Which cells should you boost, and to what number? So far, scientists do not know the answer. What is known is that the body is continually generating immune cells. Certainly, it produces many more lymphocytes than it can possibly use. The extra cells remove themselves through a natural process of cell death called apoptosis — some before they see any action, some after the battle is won. No one knows how many cells or what the best mix of cells the immune system needs to function at its optimum level.
As we age, our immune response capability becomes reduced, which in turn contributes to more infections and more cancer. As life expectancy in developed countries has increased, so too has the incidence of age-related conditions. While some people age healthily, the conclusion of many studies is that, compared with younger people, the elderly are more likely to contract infectious diseases and, even more importantly, more likely to die from them. Respiratory infections, influenza, the COVID-19 virus and particularly pneumonia are a leading cause of death in people over 65 worldwide. No one knows for sure why this happens, but some scientists observe that this increased risk correlates with a decrease in T cells, possibly from the thymus atrophying with age and producing fewer T cells to fight off infection. Whether this decrease in thymus function explains the drop in T cells or whether other changes play a role is not fully understood. Others are interested in whether the bone marrow becomes less efficient at producing the stem cells that give rise to the cells of the immune system. There appears to be a connection between nutrition and immunity in the elderly. A form of malnutrition that is surprisingly common even in affluent countries is known as "micronutrient malnutrition." Micronutrient malnutrition, in which a person is deficient in some essential vitamins and trace minerals that are obtained from or supplemented by diet, can happen in the elderly. Older people tend to eat less and often have less variety in their diets. One important question is whether dietary supplements may help older people maintain a healthier immune system. Older people should discuss this question with their doctor.
Like any fighting force, the immune system army marches on its stomach. Healthy immune system warriors need good, regular nourishment. Scientists have long recognized that people who live in poverty and are malnourished are more vulnerable to infectious diseases. Whether the increased rate of disease is caused by malnutrition's effect on the immune system, however, is not certain. There are still relatively few studies of the effects of nutrition on the immune system of humans, although more should be done. There is some evidence that various micronutrient deficiencies — for example, deficiencies of zinc, selenium, iron, copper, folic acid, and vitamins A, B6, C, and E — alter immune responses in animals, as measured in the test tube. However, the impact of these immune system changes on the health of animals is less clear, and the effect of similar deficiencies on the human immune response has yet to be assessed. So, what can you do? If you suspect your diet is not providing you with all your micronutrient needs — maybe, for instance, you don't like vegetables — taking a daily multivitamin and mineral supplement may bring other health benefits, beyond any possibly beneficial effects on the immune system. Taking megadoses of a single vitamin does not. More is not necessarily better.
Improve immunity with herbs and supplements?
Walk into a store, and you will find bottles of pills and herbal preparations that claim to "support immunity" or otherwise boost the health of your immune system. Although some preparations have been found to alter some components of immune function, thus far there is no evidence that they actually bolster immunity to the point where you are better protected against infection and disease. Demonstrating whether an herb — or any substance, for that matter — can enhance immunity is, as yet, a highly complicated matter. Scientists don't know, for example, whether an herb that seems to raise the levels of antibodies in the blood is actually doing anything beneficial for overall immunity.
1. Eat more whole plant foods and limit added sugars and preservatives.
Whole plant foods like fruits, vegetables, nuts, seeds, and legumes are rich in nutrients and antioxidants that may give you an upper hand against harmful pathogens. The antioxidants in these foods help decrease inflammation by combatting unstable compounds called free radicals, which can cause inflammation when they build up in your body in high levels. Chronic inflammation is linked to numerous health conditions, including heart disease, Alzheimer’s, and certain cancers. Meanwhile, the fiber in plant foods feeds your gut microbiome, or the community of healthy bacteria in your gut. A healthy gut microbiome can improve your immunity and help keep harmful pathogens from entering your body via your digestive tract. Furthermore, fruits and vegetables are rich in nutrients like vitamin C, which may reduce the duration of the common cold. "Eighty percent of your immune system is in the gut, so when it's healthy, we tend to be able to fight off infections faster and better,” says Yufang Lin, M.D., of the Center for Integrative Medicine at the Cleveland Clinic. In general, Lin recommends that people focus on a “Mediterranean” style of eating, which essentially means a diet rich in fruits, vegetables, whole grains and healthy fats, found in foods such as nuts and olive oil. “This eating pattern is high in nutrients such as vitamin C, zinc and other antioxidants shown to help reduce inflammation and fight infection,” she explains. Adults between the ages of 65 and 79 who followed a Mediterranean type of diet, along with taking a daily 400 IU vitamin D supplement for a year, showed small increases in disease-fighting cells such as T cells, according to a 2018 study published in the journal Frontiers in Physiology. It's also important to LIMIT MEAT, especially processed and fried foods, all of which are more inflammatory, Lin adds. “Generally, I recommend a whole food diet,” she says. What's more, it's smart to include fermented foods, such as yogurt, sauerkraut, miso and kefir, in your daily diet. These help build up the good bacteria in your gut, which, in turn, supports a healthy gut and immune system, Lin explains. Emerging research suggests that added sugars and refined carbs may contribute disproportionately to overweight and obesity. Obesity may likewise increase your risk of getting sick, and curbing your sugar intake can decrease inflammation and aid weight loss, thus reducing your risk of chronic health conditions like type 2 diabetes and heart disease. Given that obesity, type 2 diabetes, and heart disease can all weaken your immune system, limiting added sugars is an important part of an immune-boosting diet, and you should strive to limit your sugar intake to less than 5% of your daily calories. This equals about 2 tablespoons (25 grams) of sugar for someone on a 2,000-calorie diet.