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Nutrition and immune system

Dr. Conway McLean, Journal columnist

As is appropriate, great attention has been devoted of late to sickness and health. The pandemic is filling the airwaves, putting fear into the hearts of many. What we need is accurate information and smart practices. This is the domain of the physician specializing in infectious disease, therefore one who knows intimately the immune system.

Most people know very little about the immune system. This is the part of the body devoted to fighting off invading micro-organisms that are part of our world, keeping us free of local and systemic (whole body) infections. The complexity and effectiveness of our immune system is nothing short of staggering.

What are the functions of the immune system? It’s a system which is critical for survival. Our immune system is constantly alert, monitoring for signs of an invading organism. The immune system functions to keep us free of infection, be it through the skin, a skin structure or our intestinal lining. Cells of the immune system must be able to distinguish self from something else, ie “non-self.”

By now it is well-recognized the COVID-19 virus is more dangerous in the elderly population. A decline in immune function is consistently observed among older adults. Aging is also associated with increased inflammation in the absence of infection and has been found to predict infirmity. The result is seniors are more susceptible to infections and have more serious complications when they get one.

The term for this decline in immune function is immunosenescence. It reflects the deterioration of both components of the immune system, the acquired and the innate. The innate system is the ‘first responder’ to an alien invasion of a microbe. The cells of the innate system act quickly, but are not specialized. The innate system is generally less effective than the adaptive immune response. The adaptive response is able to recognize some specific invading organism and remember it later, if exposed again.

Scientists specializing in the role of macronutrients, micronutrients, and the gut microbiome are convinced they all play a critical role in the functioning of our immune system. It turns out to be an incredibly complex system, with a multitude of factors and variables. Up until recently, we knew next to nothing about our gut bacteria and its complex interaction with our health and immunity. We do know one crucial part of gut health, not surprising, is our diet. But there are many ways to optimize the effectiveness of our immunity.

A person’s nutrition can affect the microbes residing in our guts, directly altering our immune response. The microbial community in the mammalian gut is a complex and dynamic system, crucial for the development and maturation of every facet of our immune response. The complex interaction between available nutrients, the microbiota, and the immune system seem to be the most important ‘players’ in the fight against invading pathogens.

What does it take to have a healthy immune system? We know well many micronutrient deficiencies have been identified as contributors to declining immunity. It is believed these could provide opportunities for directed therapies potentially restoring immune function. Better health through improved nutrition.

Some proffered recommendations: eat yogurt for breakfast! Apparently, the probiotics strengthen the immune system, as revealed by a study on athletes and their colds and GI infections. Yogurt is also rich in vitamin D, which also boosts your immune system.

Vitamin C is well-recognized to be an extremely important part of an effective immune system and a deficit can make you more prone to getting sick. Because your body cannot store it, daily intake is essential for good health. Foods rich in vitamin C include oranges, grapefruits, strawberries, bell peppers, spinach, kale and broccoli.

Vitamin B6 supports many of the reactions that are integral to immune function. Foods high in B6 include chicken and cold water fish (eg salmon and tuna), and green vegetables. Another important vitamin to fighting infection is E, which is a powerful antioxidant. Foods rich in vitamin E include nuts, seeds and spinach.

Some people think of tea as something consumed in the movies, yet studies reveal alkylamine, a naturally occurring chemical in tea, strengthens the immune system, again, helping it fight off infection more effectively. Honey has centuries of use because of its medicinal properties. Numerous reviews find honey, an antioxidant, acts as a natural immunity booster.

Another suggestion made by researchers is to eat more garlic, since it seems to stimulate many different cell types essential to the immune system. Ginger, another powerful antioxidant has antiviral properties, probably a good idea these days. Consume more lemon. Lemon juice is high in vitamin C, and can be used for its antioxidant properties and to prevent the common cold.

How about a bowl of chicken soup? Thought by some to simply be a comfort food, the dish has a mild anti-inflammatory effect. Ingredients in the classic recipe (chicken, garlic, onion, celery, etc) have been found to slow the migration of white blood cells into the upper respiratory tract, helping to relieve the symptoms of a cold. Additionally, a compound found in chicken soup called carnosine seems to prevent colds. How about a nice bowl of curcumin? This is a component in the spice called turmeric. Studies have shown curcumin helps to regulate the immune system.

Zinc is known to be an important micronutrient for the immune system. Even a mild deficiency in zinc has been associated with widespread defects in the immune response. Look to fish, seeds, nuts, broccoli as good food sources. Selenium is a trace element that also has critical functional, structural, and enzymatic roles. Inadequate selenium is associated with a higher risk for a variety of chronic diseases since it is critical to immune function. Foods containing higher levels of this mineral include spinach, lentils, eggs, and fish.

Some of the recommendations for immune health are related more to lifestyle modifications. Making workouts a part of your weekly regimen since regular exercise increases the activity of immune cells. Exercise also seems to flush bacteria out of your lungs, reducing the likelihood of an airborne illness. Experts suggest moderate levels of intensity, performed 4 to 5 times a week for 30-40 minutes.

Staying hydrated is required for immune health. Water helps your body produce lymph, which carries white blood cells and other immune cells. Sun exposure is important (although difficult in certain climes) since it is the most efficient way to stock up on vitamin D, an immune system supercharger. Surprisingly little is needed, just 15 to 20 minutes a day, to get the recommended dosage.

Getting the flu shot improves your immune profile, and is approved for all adults. Smoking suppresses the immune system generally, so quitting is good for you in terms of the risks of an infectious disease. It also damages the lining of our “windpipes”, explaining why smokers are much more likely to catch a cold virus.

Nutritional modulation of the immune system has application in the clinical setting, meaning nutritional therapies should be prescribed in your average doctor’s office, although this rarely occurs. This therapeutic approach should be utilized more consistently in those demonstrating poor immune function, as well as for healthy populations.

Editor’s note: Dr. Conway McLean welcomes questions or comments atdrcmclean@outlook.com.

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