Guest Writer: Timi Gustafson, RD
It is the time of the year again when many of us get the sniffles, wondering when there will be a cure for the common cold at last. Of course, not everybody will fall sick. Some people seem to remain unscathed no matter what, while others succumb as soon as the temperatures drop. It’s a mystery how a chosen few can handle the germ assault so much better than the rest of us. These folks must have an extraordinarily robust immune system that protects them like an invisible shield. But were they born this way or did they acquire their immunity over time. And if so, how?
Humans have three types of immunity: “Innate,” “adaptive” and “passive.” We all are equipped with “innate” or “natural” immunity at birth. It is our first line of defense against the countless health hazards we become exposed to the moment we begin to breath. We also have external barriers, like our skin and the membranes that line the nose, throat and gastrointestinal tract. If any of these outer defense walls break down and an opening occurs, e.g. through an abrasion or cut, immune cells keep pathogens from invading while the wound heals.
By contrast, “adaptive” immunity is a defense mechanism we acquire as we encounter various diseases or become intentionally immunized through vaccinations. It is a process that continues over the duration of our lifetime.
“Passive” immunity only lasts for a limited period. For instance, we receive certain antibodies as infants from breast milk, protecting us initially from the infectious diseases our mother carries anti-bodies against. But that kind of protection is only temporary.
As we get older, our immune system should grow increasingly stronger and more efficient, simply because it recognizes many germs from past encounters and eliminates these faster. Unfortunately, that is not always the case. Immunity disorders and allergies can severely diminish our natural defenses. But if it functions properly, the immune system is a magnificent asset without which we would not survive for long.
Fortunately, we have also means to strengthen the immune system’s capacity. Most people may think in terms of vaccinations. However, one of the most effective ways to boost the immune system is through a healthy, balanced diet. Experts believe that eating lots of fresh fruits and vegetables is probably the single best thing one can do to support the immune system and thereby ward off many infections.
Some of the most important nutritional benefits we can get come from antioxidants. Antioxidants are vitamins, minerals and other nutrients that help to protect cells in the body from damages caused by so-called “free radicals.” These are highly unstable organic molecules, mostly generated by exposure to toxins, which can adversely affect cells and tissues and thereby contribute to diseases and aging. They can also impact the immune system and interfere with its functions. Antioxidants are believed to prevent these free radicals from doing their harmful work. Including lots of rich sources of antioxidants in one’s diet is therefore highly recommended as a preventive measure against colds and other infections.
Certain foods contain higher levels of antioxidants than others. Look for fruits and vegetables that are high in beta-carotene and other carotenoids. You can easily recognize them by their bright colors, like orange, purple, red and yellow. Apricots, cantaloupes, mangoes, nectarines, peaches, grapefruit, tangerines and watermelons are all fruits rich in beta-carotene. So are vegetables like asparagus, beets, broccoli, carrots, bell peppers, kale, collard greens, squash, spinach, sweet potatoes and tomatoes.
You may want to include good sources of essential vitamins and minerals as well. Vitamins A, C, E and the mineral selenium (all antioxidants), B-complex vitamins, iron and zinc are especially beneficial for the immune system. Vitamin C and E are present in many produce items and are readily available for most of the year. Vegetables like broccoli, cauliflower, Brussels sprouts, citrus fruits and berries are loaded with them. Foods that can be found in colder climates during the fall and winter season are prunes, apples, raisins, plums, grapes as well as onions, eggplants, beans, squash, pumpkins and sweet potatoes. The richest Vitamin E sources are wheat, nuts, seeds and also certain fruits and vegetables.
All these foods contain many more varieties of nutrients that work together in support of the immune system and have other health benefits too. Some have important anti-inflammatory properties, which can be used for the treatment of allergies and other inflammations.
With regards to their nutritional value, natural sources of antioxidants are preferable to vitamin supplements. However, in order to avoid deficiencies, I do recommend a daily multivitamin supplement, at least during the cold season. Supplements are never to be considered a substitute for real food, but they can serve as useful additives, especially when your diet is less than balanced. However, I do not advise taking specific immune boosting supplements or medications, unless prescribed by a doctor for therapeutic purposes. The reason is that some vitamins (like A and E) are not as easily eliminated as others (e.g. vitamin C) and may accumulate to the point where they become toxic.
Last, but not least, it needs to be said that good nutrition alone will not guarantee the immune system to function at top level. Stress management and sleep hygiene are also part of the equation. If you are too run down from work or sleep deprivation, the best food in the world will not prevent you from having to pay the price eventually. But with all (or most) of your health needs met, you should make it through the coming winter just fine. Perhaps, this time you will be among the chosen few who stay above the fray, no matter what.
Timi Gustafson RD, LDN. is a clinical dietitian and author of the book “The Healthy Diner – How to Eat Right and Still Have Fun”®, which is available on her blog, “Food and Health with Timi Gustafson R.D.” (http://www.timigustafson.com), and at amazon.com. You can follow Timi on Twitter and on Facebook.