Aging can bring all sorts of gifts, whether it’s wisdom and experience, new opportunities or connecting in a new way with your adult children and grandchildren. (I’m a big fan of grandparenting!). Things can get tough though with some of the physical changes that can take place in our bodies, typically, taking root in early middle age and gathering speed from there. 

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Another change that comes with the gift of years? One of the most important ones concerns our immune system, our body’s defense against threats from the outside world and from inside us as well. Often, it’s something we’re hardly aware of – maybe a winter flu hits us harder than usual – until the decline manifests in a more obvious way, often in our senior years, for instance, taking shape as a life-threatening case of pneumonia or an auto-immune disease like rheumatoid arthritis. The way to push back is to understand the process of “immunosenescence” (the weakening of the immune system) and to use every tool in your healthy lifestyle toolbox to make sure that it doesn’t gain the upper hand. Here's a primer on understanding the aging immune system -- and a few thoughts on how you can best help it help you. 

Immunity’s slow slide.

Our immune response is actually managed by two distinct teams of cellular “bodyguards”, the acquired (or adaptive) immune system and the innate immune system, and they age in different ways. Most of us are probably more conscious of the acquired system -- we wonder if ours is sputtering if we catch a particularly nasty case of the flu (the influenza virus) or a bad cold (caused by an assortment of rhinoviruses). The acquired system is driven by a collection of cells that learn to recognize specific invaders, usually viral. Then your body ramps up the production of these antibody cells to neutralize the threat. By the time we start collecting Social Security, the thymus gland that produces these cells dramatically shrinks and we wind up with a smaller supply of “blank slate” cells able to be programmed to deal with new challenges. Exhibit A is the weaker response that seniors have to vaccinations, designed to arm immune cells to go after a specific enemy. Here’s another common scenario: the aging immune system sends out antibodies to attack CMV, a more or less harmless virus which, by middle age, most of us carry. The attack isn’t strong enough to clear the virus and so the attack never ends, decade after decade, depleting the immune system of cells that could be otherwise used to thwart real enemies. 

Inflammaging is nothing to sneeze at.

The other immune system team accounts for the innate immune response. We’re all familiar with it –the swelling or the high body temperature that follows an injury or an infection -- but we don’t always appreciate that these are the body’s first-line protection against injury or infection. It’s a “non-specific” response – the body throws pretty much the same weapons at the problem no matter what it is, for example, the swelling that cordons off an injured area so that other cells can get on with the repair process. This kind of immune response is absolutely necessary – without it, we’d never get out of childhood alive. But just as our acquired immune response grows weaker with age, our innate system becomes more prone to discombobulation. It grows ever more ready to send out inflammatory proteins called cytokines to counter a threat and less and less good at shutting them down when the threat has passed. As best we know, that’s what happens in severe COVID 19 cases – the cure (the inflammation) turns out to be much worse than the disease (the infection itself). 

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This kind of indiscriminate and chronic inflammation is so common in the aging body that researchers often use the term “inflammaging” to describe much of what goes seriously wrong with us as we grow old. Inflammation is a major driver, arguably the major driver, of the “diseases of aging” which, sooner or later, shorten most of our lives – heart disease, diabetes, cancer and so on. A misfiring innate immune system is also thought to be the culprit behind common auto-immune conditions like rheumatoid arthritis, lupus, and inflammatory bowel disease – especially common in women. The immune response goes so haywire, it sends out cells to attack the body’s own tissues. 

‍Movement to the rescue.

The good news here – and there is actually quite a lot – is that by moving the body, you can help slow down the aging of the immune system. There have a been a raft of studies that have shown that exercise – whether moderate or vigorous – can improve the markers that we use to measure immune function. There’s no one way physical activity accomplishes this. Aerobic exercise, like walking, jogging and cycling, helps keep metabolism on an even keel, tamping down insulin resistance, a major cause of inflammation. Strength-building exercise preserves our muscle mass which we’re learning also plays a key role tamping down inflammation. The latest research is looking at chemicals produced by muscles when they’re firing, “myokines,” which produce similar benefits. As always with movement, it pays to be aware of the Goldilocks problem. Too little is no good – you’re prone to losing muscle tissue and adding fat tissue, which spits out its own menu of inflammatory cytokines. Ditto, too much. Especially for middle-agers and seniors, exercising too intensely over too long a period of time, depletes your immune response which is an invitation to a respiratory infection or hard-to-shake fatigue, or worse. But breaking up a mostly moderate session of movement with a burst of higher-intensity effort can generate a healthy stress on the immune system. (“Hormesis” is the technical term). It doesn’t have to be sprinting to exhaustion in a spin class – something as simple as alternating speeds between fast and moderate when you’re out walking can help keep immunity humming.

Feeding your immune system. 

I believe a healthy diet is a crucial way to slow down the aging of your immune system (and every other part of you), an assertion that, by now, should surprise none of my patients or my readers. Once again, we’re in the business of countering inflammation. A diet high in plant fiber and healthy fats (omega 3s especially) and low in in refined carbohydrates (processed sugary foods are the worst) is the way to go. The fiber in non-starchy vegetables like the leafy greens and the cruciferous veggies feed the good bacteria in your gut microbiome, helping the gut immune system to avoid overreacting to non-toxic gut invaders and preventing toxins from leaking through the gut wall, both sources of gut-driven inflammation that can compromise the immune system. 

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And, when it comes to eating well, timing it strategically can help tune down inflammation and tune up the immunity. For example, there’s also plenty of intriguing research on eating strategies like intermittent fasting, or its first-cousin, time-restricted eating, which compress eating daily meals into a shorter time-period, say, eight hours, stressing your metabolism in a healthy, anti-inflammatory fashion during the fasting periods. 

‍Supplemental insurance for the immune system.

We know that antioxidant vitamins like A, C and E are necessary for the proper functioning of your immune system. But there’s usually no need to load up on single-vitamin supplements. A good multi, including D and zinc, should serve as dietary insurance policy to make sure you’re providing your cellular bodyguards with the nutrition they need. The real supplemental stand-out here though may be the omega 3s. My integrative medicine colleague Jeff Bland has published persuasive research highlighting the role that these supplements can play in ensuring a well-balanced and properly functioning immune system.  So, if you’re feeling like your body’s not fighting off invaders all that well, a high quality omega 3 supplement can help keep a spring in your step.

‍The stress/sleep connection. 

Too much stress and too little sleep – in practice, it’s hard to disentangle the two – do a number on the immune system, aging it before its time. Keeping your adrenal glands in overdrive results in chronically high levels of cortisol which have, you’ve probably guessed it by now, a pro-inflammatory effect. A small library’s worth of studies have established that people whose lives are especially stressful, caregivers for example, pay a steep immune function price. Likewise, sleep deprivation, less than six hours a night, pumps up the cortisol and works to harm the body in other ways as well. (I recommend at least seven hours nightly.) It’s well established that low sleep increases susceptibility to disease and significantly increases the risk of death from any cause. The antidote isn’t complicated. Carve out the time, and the conditions, for sound, ample sleep and keep chronic stress at bay with whatever combination of stress-tamers suits you and your lifestyle. I’m partial to yoga, sitting meditation and spending time in nature. Other people swear by the sauna or a hot bath before bed. Whatever speaks to you in a calming tone – go for it.