Immune Function and Aging: Extending Health

Immune Function and Aging: Extending Health

There is a reason why the older people get, the more likely they are to develop a serious illness. In fact, they are twice as likely to visit the doctor, three times more likely to be hospitalized, can respond poorly to vaccines, and can have re-occurrences of previously defeated diseases. In early life, the human immune system is a marvelous thing. It functions efficiently and ruthlessly, switching into defense mode only when needed to deal with pathogens, and then switching off to avoid prolonged inflammation. All fine for a while, but then as time progresses and we are using and depleting our supply of immune cells, our ability to respond degrades, chronic inflammation takes its toll, and we become subject to increased morbidity and disease. 

Our immune system is in this way much like a car -- after an extended period of use, it just wears down, and eventually stalls. As a result, it often fails to deal with attacks. Scientists call this immune senescence; the aging of the human immune system. It is now recognized as the underlying cause of many significant health issues, including degenerative diseases, diabetes, and cancer (Immunity & Ageing 2012.) In the past, doctors have addressed individual illnesses as they occur, but what we are learning is that without dealing with the fundamental problem of immune aging, we are only ever putting band-aids on symptoms.

Immune function and why it breaks down.

Your immune system is divided into the innate and the adaptive branches. While the two must work together, the innate branch is the front line (skin, tears, perspiration, stomach acid), taking initial non-specific defense against infection and attack. Any time bacteria invade, or a cell mutates, or is virally infected, the innate system launches an immediate counterattack.

Then, the adaptive immune system branch gets involved, using antibodies, antigen presenters, lymphocytes, cytokines, and T-cells, which are in a real sense the 'brains' of the entire system, to respond intelligently and precisely to threats. Without T-cells, even a small cut or cold would be fatal. Each time naive T-cells are called into action, they 'remember' the pathogen and the required solution, store this information, and then become memory T-cells for future use (if there is a re-occurrence they can respond quickly and specifically.)

Problems really start with the shrinking of the thymus gland as we age, which is the main source for T-cells, and so the adaptive branch becomes increasingly less effective over time. Furthermore, as the basic naive T-cells are depleted (converted and not replenished), and all we have left is our store of memory T-cells, the body loses its ability to adapt to new attacks, and only responds to known invaders (and even these lose capacity over time.) This leaves us open to new risks, which will always eventuate, and without a defense will be devastating to health. Of course, I am over-simplifying, but I am heading toward a discussion of nutrition.

As I mentioned above, as we age we are also unable to properly deal with inflammation. Our regulatory immune cells normally know when to switch off the inflammatory response. However, as a result of immune senescence, regulatory cells degrade and inflammatory cells are left to run a-muck, promoting free radical production and causing serious system-wide damage. 

In order to stave off immune aging, we need both systems operating as efficiently as possible. 

So how do we slow down the immune system aging process?

It is an unfortunate fact of life that we age. Our environment, chemicals, toxins, stressors, and poor diets only hasten the process of immune senescence. But there are ways to slow it down and help keep our immune systems at peak function. Science tells us that aging is modulated by genetics, environment, lifestyle, and nutrition. For this discussion, I'll focus mostly on what is now called nutritional immunology.

Before I go any further, let's state the obvious. Don't smoke! Nothing does more damage to our immune function than cigarette smoking.

Next, pay attention to your stress levels. A study which tested medical students for the production of immune cells after a major exam, found that high stress levels significantly affected the body’s immune-cell distribution and its ability to fight off disease (Journal of Interferon and Cytokine Research.)  

"Life stress overall is associated with accelerated telomere loss which likely contributes to the association between stress and age-related disease" (Epel et al., 2004).

A good way to combat stress and promote immune function is to get regular exercise (Simpson and Guy, 2010.) It doesn't need to be vigorous -- regular 40 minute brisk walks are perfect.

There is also strong evidence for the value of caloric restriction in immune health

Also, watch out for food allergies. Eating food that you are intolerant of or causes an allergic reaction is highly damaging to your immune system. On the flip side, make sure to feed the healthy gut flora with probiotics. A large part of your immune system is in your gut.

Which brings us to food.

Nutrition for immunity.

When it comes to nutrition, it gets a little more complicated. I look at it as two basic groups: nutrition for stability and for enhancement. We have been studying the effect of food, mostly from a deficiency perspective, on immune function for many years, and we know quite a lot about which dietary deficiencies exacerbate or cause immune dysfunction. However, over the last two decades, research has identified specific compounds in food that can stimulate both branches of the immune system (Clinical Infectious Diseases, Vol 33;11.) So, we can on one hand recognize the foundation for proper immune health, and one the other, we can find ways to augment or enhance it.

Given our current understanding of the biochemistry, it is safe to say that the best approach is to feed the innate immune system the resources it needs and let it make its own decisions. This is what I call the stability group, ensuring the nutrient resources for proper general immune function. These include foods rich in key micronutrients and macronutrients, phytonutrients, anthocyanins, polyphenols, and antioxidants.  Read more about what foods to eat to boost your innate immune function in this post.

When it comes to the enhancement of immune function, research has at very least shown us that T-cell production must be a minimum level for optimal health, and so stimulating T-cell growth can be very useful, and can be accomplished through nutrition. Studies showed that certain foods not only stimulate the creation of T-cells, but also enhance cell survival by reducing apoptosis.

Vitamin E:

This antioxidant vitamin has been investigated as a preventive measure for many human conditions, including heart disease and cancer. It is widely believed that it also boosts immune responses in elderly recipients. It is not fully clear how vitamin E augments immune responses, but animal and human studies have reported a protective effect of vitamin E against infection. It is currently believed it may do so by altering cytokine generation from T cells or macrophages, by directly influencing membrane integrity and signal transduction in T cells, or by reducing production of suppressive factors, and while we may still be learning, it is clearly helpful to maintain good vitamin E levels. 

Look for foods like almonds, hazelnuts, any seeds (sunflower, sesame), all leafy greens (kale, spinach, chard), olives, avocados, and parsley.

Zinc:

Zinc is involved in many immune functions, and its deficiency affects multiple immune cell types involved in both innate and adaptive immunity. Most importantly, low levels can lead to thymus involution, a reduction in T-cell production, lymphocyte proliferation, natural killer cell activity, and many other immune dysfunctions. Studies show that zinc, and selenium, given daily, regardless of whether with or without vitamins, decreased infection rates in subjects (NK and NKT cell functions in immunosenescence. Mocchegiani E, Malavolta M, Aging Cell. 2004)

Look for foods like oysters or any molluscs or crustaceans, meats like free-range pork, beef and lamb, bran cereals, beans, alfalfa, endive, seaweed, squash, basil, and chervil.

Glutamine:

Glutamine is also an important fuel for lymphocytes and macrophages. Research evidence suggests that glutamine is used at a very high rate by these cells, even when they are quiescent (Newsholme, 1994), so replenishment is important.

Look for high-protein foods like grass-fed beef, chicken, lamb, fish, and free-range eggs.

Fish Oil:

It's amazing how often we mention fish oil for one health benefit or another. Again, it is highly valuable to immune function. Omega fatty acids (mainly EPA and DHA) are not only fundamental nutrients for energy, but also have significant effects on specific immune cell functions. They are anti-inflammatory, inhibit production of inflammatory mediators, and have clear beneficial effects on cardiovascular disease, degenerative neurological diseases, inflammatory and autoimmune diseases, and age-related macular degeneration.

Look for the fatty fishes like salmon, anchovies, mackerel, tuna, trout, and sardines for optimal levels of omega's.

Echinacea:

Echinacoside, a compound in echinacea, benefits immune function by potentially preventing the premature conversion of naïve T-cells into memory T-cells. As I explained above, the loss of available naive T-cells is a major problem in aging and maintaining good long-term health.

Mushrooms:

Several species of mushrooms have shown to be highly beneficial to immune function. If you have never had these mushrooms before, start with small amounts and gauge your response.

Shiitake mushrooms not only contain a dense array of key nutrients but also are known to combat bacteria and yeast infections.

Reishi mushrooms may sound oddly familiar to you, likely because of its etymology, literally meaning 'spiritual power.' In research it has consistently shown to have potent anti-viral, anti-inflammatory, anti-parasitic, and anti-tumor characteristics. Reishi is often used for people suffering with depressed immune systems like chemotherapy patients, and extracts have been shown to stimulate cell-killing activity, which is important since these cells help eradicate both virus-infected and malignant cells. It stabilizes blood pressure, protects the liver, inhibits platelet aggregation, and aids immune resistance. In one animal study, mice taking reishi were less negatively affected by aging and lived longer!  Reishi seems to have a particular benefit to the innate immune branch.

Maitake mushrooms, which look like little hen's tail feathers, are arguably the most important of the mushrooms, and maybe any immune enhancing nutrition. They reduce the risk of high blood pressure, diabetes, and stroke, and are even used in immunotherapy to complement surgery, radiotherapy, or chemotherapy. Some studies suggest an increase in patient response rates of up to 28%, and have shown particular promise as a supplement to HIV therapy.

Aloe vera:

While there is still debate about the food, aloe vera seems to have anti-inflammatory effects and may modulate immune response.

Also, read about garlic and ginger as immune boosting foods.

In general, a diet rich in vegetables, fruits, seeds, nuts, legumes, and lean proteins is the basis for good immune system health.

Finally, research acknowledges that supplementation shows clear benefit. Look for high quality whole-food anti-aging vegetables and antioxidant-rich fruits supplements that draw on nutrition from the list above, as well as from our discussion of telomere health.

We just cannot ignore the dangers that immune senescence poses to our long term health. Make sure to feed your immune system so it has the resources to stave off the problems associated with aging for as long as possible.

Related Posts:  
4 G's for Anti-Aging: Garlic, Ginger, Ginseng & Gingko 
Secrets to Staying Young & Preventing Aging Through Food

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References:
Ongrádi J, Kövesdi V. Factors that may impact on immunosenescence: an appraisal. Immun Ageing. 2010 Jun 14;7:7.
Candore G, Caruso C, Jirillo E, Magrone T, Vasto S. Low grade inflammation as a common pathogenetic denominator in age-related diseases: novel drug targets for anti-ageing strategies and successful ageing achievement. Curr Pharm Des. 2010;16(6):584-96
Rabb H. The T cell as a bridge between innate and adaptive immune systems: implications for the kidney. Kidney Int. 2002 Jun;61(6):1935-46.
O’Sullivan T, Saddawi-Konefka R, Vermi W, et al. Cancer immunoediting by the innate immune system in the absence of adaptive immunity. J Exp Med. 2012 Sep 24;209(10):1869-82
Macrophage prostaglandin production contributes to the age-associated decrease in T cell function which is reversed by the dietary antioxidant vitamin EMech Ageing Dev 1997;93:59-77.
The aging immune system: primer and prospectusScience. 1996;273:70-4.
Miller RAAging and immune function. In: Paul WE, editor. Fundamental immunologyPhiladelphiaLippincott-Raven1999. p. 947-66
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The opinions expressed in this article are of the author. Content and other information presented on the site are not meant to be medical advice or any substitute for professional advice, counseling, diagnosis, or treatment. Never delay or disregard professional medical or mental health advice from your physician or other qualified health provider.

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