How much do you know about your immune system? Our resident RDs have some simple, evidence-based nutrition advice to help you keep it fighting fit.
IMMUNE SYSTEM 101
The immune system is an intricate network of specialized cells, organs and processes that protect the body from pathogens: micro-organisms that can make us ill. There are different types of pathogen that cause disease - including bacteria, viruses, certain parasites, and fungi - and within each category there are numerous different species. That means your immune system has to be super responsive and adaptive to repel all these attacks, and it does so with three lines of defense:
1. External barriers, including the skin, the mucous membranes that line your GI tract, eyes, and respiratory system, and the acid in your stomach. Think of these as the castle walls.
2. Internal barriers, made up of immune defense cells such as white blood cells that ‘eat’ pathogens by enclosing and digesting them. Think of these as the soldiers that guard the castle. These first two barriers make up what’s called your ‘innate immunity’.
3. The third layer is called adaptive immunity, and you develop it throughout your life thanks to antibodies acquired after successfully fighting off a previous infection. Antibodies are proteins that can identify and target specific pathogens and infected cells. Think of them as the hired guns or specialist snipers.
Not everyone has the benefit of a healthy immune system. Auto-immune diseases are so called because they cause the immune system to become overactive and start attacking the body’s own cells. Some other chronic conditions, treatment regimes like chemotherapy, and certain prescribed medications have the opposite effect, weakening the immune system and making it much harder for the body to defend itself. What’s more, the effectiveness of your immune system develops through childhood and early adulthood, and naturally declines with age. So it’s no surprise that viral illnesses are often more serious in the very young, older people and those with existing health conditions. Be mindful of these vulnerable individuals; all those precautions that health professionals recommend - washing hands, staying home if you’re sick - protect them as much as they protect you.
Even if you’re not immune-compromised through illness, there are plenty of lifestyle and environmental reasons that might cause you to get infections more often than other people. Environmental toxins, a nutrient-poor diet, lack of sleep, smoking, too much alcohol, and lack of exercise can weaken the immune defense system at any age. Stress is another big one. Acute stress or anxiety triggers your nervous system to release a flood of hormones like adrenaline and cortisol. Our ‘fight-or-flight’ response to stress is useful as a short-term, occasional reaction to danger: it speeds up your pulse and breathing rate and may briefly increase immune system activity. That’s fine if the body returns to normal functioning soon afterwards. However, this response evolved to help us run away from old-fashioned kinds of danger (you know, like lions or bears), rather than the more insidious threats we face today. When stress becomes a constant (chronic) state, your nervous system may never get the signal to ‘stand down.’ As a result, your immune system can become weakened, compromising your ability to fight infections.
EAT FOR THE WIN!
An immune system that’s functioning normally will do its best to protect you. But you can really help it out, by providing it with the nutrients it needs to fight infections and unwanted organisms that make us sick. Think about it as an engine; it needs gas to run, and higher quality gas can improve the engine’s performance. So, here are some premium fuels to make your immunity engine run better:
Fiber for a healthy gut
Believe it or not, the interaction between the microbes that live in your gut and your immune system is key to its proper functioning. Consider that a healthy gut is home to hundreds - possibly thousands - of different species of beneficial bacteria, and that your immune system is capable of destroying pathogens, including bacteria, and you’ll see that one essential task of the immune system is to maintain a balance between reaction and tolerance. A diverse, healthy population of ‘friendly’ bacteria is crucial for this; it appears that it supports the development of the immune system by fine-tuning its ability to distinguish between ‘friend’ and ‘foe’. Your gut’s resident ‘friendly’ microbes thrive on fiber, which is only found in plant foods, so be sure to feed them a plentiful and varied diet.
Find it in: fruits and vegetables, whole grains, legumes, and nuts. A kencko smoothie has the same amount of fiber as a cup of brown rice. (Yes, really! Around 3.5 grams.)
Vitamin A to strengthen innate immunity
Remember that first line of defense, the mucosal cells that line our GI tract, eyes, and lungs? Vitamin A helps maintain the structure of mucosal cells so that they can perform their protective functions. It also plays an important part in generating antibodies, which are necessary for the body to identify and fight pathogens.
Find it in: sweet potato, pumpkin, carrots, spinach, red bell peppers. Get a hefty boost of vitamin A in kencko rubies and yellows.
Vitamin C to support immune cells
When fighting “invaders” in our body, immune cells generate what are known as reactive oxygen species (ROS), molecules that can cause damage to cells, DNA, and proteins. By functioning as an antioxidant, vitamin C is able to neutralize ROS, preventing or repairing damage to other cells. Lab studies show that vitamin C is able to enhance immune function by increasing the production of white blood cells (those responsible for protecting the body against infection) so it can be an important player in keeping your immune system up-to-speed. But in order to ensure this, you need to get a consistent supply of vitamin C through your day-to-day food choices, even when you don’t have any symptoms. That’s because our body can’t store vitamin C, and can only absorb a certain amount each day, so there’s no real benefit to slamming 1000mg when you feel a cold coming on! Adequate daily intake is the key.
Find it in: Citrus fruits (orange, grapefruit), bell peppers, kiwi, strawberries, broccoli, tomatoes. kencko’s high-C stars are corals (supplies 95% of daily needs), greens (66%), and reds (59%).
Zinc for optimum defenses
Zinc is an essential mineral that doesn’t always get enough credit. It’s a big player when it comes to immunity - we need it for the growth and development of immune cells, and it makes up the structure of proteins that protect immune cells from damage. Even more impressive, lab studies indicate that zinc may be able to physically block the attachment of viruses, specifically rhinovirus, to the cells of the nasal cavity. However, human studies are needed in order to further understand how - and if - this happens in humans.
Find it in: plant sources of zinc include brown rice, black beans, chickpeas, lentils, tofu, nuts (cashews, pine nuts, pecans), seeds (pumpkin, sunflower), fortified grains and cereals. (It’s also plentiful in oysters, poultry and red meat.)
Vitamin E to enhance adaptive immunity
A fat-soluble antioxidant, vitamin E protects cells from damage by free radicals and therefore supports proper immune function. Vitamin E is especially helpful when it comes to the adaptive immune response, the one which we acquire after successfully fighting an infection. As we age, it is natural for immune function to decline. In one study, vitamin E was shown to enhance immune response in older adults, which may decrease susceptibility to infections in those individuals.
Find it in: nuts (almonds, peanuts), spinach, broccoli, kiwi, mango. There are vitamin E sources in kencko yellows or greens.
BUT WHERE’S THE MAGIC PILL?
Looking for easy answers is a human thing. We all do it. If the immune system needs vitamins and minerals, then popping a vitamin pill (or twelve) when you start to feel a sniffle coming on seems like it should work, right? Actually, while supplements may help people who are deficient in one or more micronutrients (meaning you had your blood tested and levels were under the desirable range), most healthy individuals are better off meeting their needs through food intake rather than supplementation. Vitamins and minerals found in foods like fruits and vegetables are more bioavailable than the artificial equivalents found in supplements - that means your body can absorb them more effectively. Plus, foods provide just the right balance of nutrients which work in synergy to improve absorption, and they supply many other beneficial phytochemicals. Supplements, on the other hand, most often provide a large amount of a single nutrient, making it easier to overdo it.
Nourishing your body with whole foods, including at least five servings of fruits and vegetables every day, is the best way to fuel an efficient immune system - one that’s well equipped to fight off infection. Having said that, there are a few occasions when a pill may help to reduce the symptoms or severity of common viral infections. Here’s what the evidence tells us:
● Routine supplementation of vitamin C may reduce the occurrence of the common cold in individuals undergoing high physical stress (marathon runners, skiers, soldiers), but supplementation did not reduce the incidence of colds in the general population.
● High doses of vitamin C supplementation may decrease the duration of a cold by 1-1.5 days when consumed regularly, but did not show any benefits when taken after the onset of cold symptoms.
● Zinc supplementation may shorten the duration of colds by as much as 33% when taken within 24 hours of symptoms onset.
● Low vitamin D levels are linked to higher risk of upper respiratory tract infections and supplementation may reduce the risk of acute infection.
● Echinacea, an herbal supplement, appeared to be beneficial for preventing and treating the common cold in a few studies; however, the evidence is weak and more research is needed.
ANYTHING ELSE I CAN DO?
Yes, absolutely! Besides the basics of striving for a healthful diet and doing what you can to manage your stress levels, there are three other important things you can do to keep your immune system running at its best.
Washing your hands regularly and thoroughly; covering coughs and sneezes, and putting tissues in the trash; avoiding touching your face: all these are good precautions to take throughout the cold and flu season - and all year round, especially if your immune system or that of a loved one is compromised. Paradoxically, living in a clinically sterile environment is not ideal for lifelong immunity. It’s thought that exposure to normal levels of environmental pathogens is essential to develop a healthy immune system in the first place, particularly in growing children. So try not to stress out about the fact that microbes are a part of life!
Getting adequate sleep can help your body stay strong to fight infection. Studies show that during sleep, your immune system releases cytokines, a group of proteins that act as chemical messengers that help regulate immune response. They ensure communication between immune cells, stimulate movement of cells towards the site of infection, and target inflammation. Sleep deprivation may decrease the production of these proteins, which decreases the body’s ability to respond to colds and infections. Aim for 7 to 9 hours of sleep if possible, and definitely skip those all-nighters.
Moving your body improves overall blood circulation, allowing immune cells to perform their jobs more efficiently. Studies suggest that moderate to vigorous physical activity (30-60 minutes daily) may enhance immune defense by improving the exchange of immune cells between the blood and affected body tissues, and improving the anti-pathogen activity of those cells. So consistent exercise can certainly help you maintain a strong immune system. P.S. Exercise goes hand in hand with rest - if you’re feeling unwell, rest is always best.
We hope this advice and information is reassuring, and wish you and your loved ones the best of health.