Staying healthy is all about supporting your immune system, which can be tougher to do in the winter and especially during the holiday season when we are often surrounded by so many unhealthy foods at every turn! However, there are lots of immune-boosting nutrients that can be found in many common and delicious foods that are available during the winter season and throughout the year. Including plenty of these in your diet, and choosing these foods first when faced with a spread of goodies, can help you stay healthy and well throughout the winter season.
Below are 4 important immune-boosting nutrients and some of the most common foods that contain them, both vegetarian and animal-based:
According to The American Society for Nutritional Sciences, “Selenium is essential for the efficient and effective operation of many aspects of the immune system in both animals and humans.”1 And selenium is a mineral that many people, around the globe, are not getting enough of. Some experimental studies suggest that low selenium intake may be contributing to “reduced immune function, increased cancer incidence, and increased susceptibility to viral disease.”2 And this isn’t just happening in poorer nations suffering from drought and food shortages. Selenium deficiency has become a first world problem.
Vegan sources of Selenium include:
- Brazil nuts
- sunflower seeds
- oat bran
- wheat bran
- rice bran
- fortified breads
Other selenium sources include caviar, liver, shellfish (oysters, whelk, mussels), fish, bacon, pork chops, shrimp (prawns, camarones), lobster and crab. It should be noted, however, that you can get far more selenium from a handful of Brazil nuts than from any of these animal sources.
Zinc may be even more critical to immune system functioning than the other nutrients. According to the American Journal of Clinical Nutrition, “Zinc is known to play a central role in the immune system, and zinc-deficient persons experience increased susceptibility to a variety of pathogens. The immunologic mechanisms whereby zinc modulates increased susceptibility to infection have been studied for several decades. It is clear that zinc affects multiple aspects of the immune system, from the barrier of the skin to gene regulation within lymphocytes. Zinc is crucial for normal development and function of cells mediating nonspecific immunity such as neutrophils and natural killer cells. Zinc deficiency also affects the development of acquired immunity by preventing both the outgrowth and certain functions of T lymphocytes such as activation, Th1 cytokine production, and B lymphocyte help…”3
Without sufficient zinc in the diet, our health and ability to function normally, and even to procreate3, are severely compromised.
Vegan sources of Zinc include:
Beans, whole grains, wheat germ, dried watermelon seeds, pumpkin and squash seeds, dark chocolate, cocoa powder, peanuts, and fortified cereals.
Other zinc sources include dairy products and meats like lamb (mutton), crab, roast beef, veal liver and oysters.
Antioxidant phytonutrients are also outstanding immunity enhancers. There are more than 25,000 kinds of phytonutrients5, including carotenoids (mentioned in part 1), polyphenols and flavonoids, which we’ll explore further here… The most renowned immunity enhancing phytonutrients are Quercetin and Luteolin.
Quercetin is an excellent inflammation fighter. It has also been found to reduce allergies and boost immune response. In one mice study, published in Nutrition Research and Practice, it was shown that quercetin could counteract the inflammation and immune system issues caused by radiation treatments…
Other studies have demonstrated quercetin’s ability to significantly strengthen immunity in both Humans and animals exposed to the flu virus, even if exposure follows stressful exercise.7
Quercetin can be found in the skin of…
- red and black grapes
Quercetin is also found in onions, capers, lovage, chamomile tea, green tea as well as a number of other foods and beverages.
Multiple studies have shown that luteolin, in addition to boosting immune system response, acts as an active “scavenger” of free radicals and may help protect the body against the damage of radiation and chemotherapy.8 This isn’t surprising, as luteolin is structurally related to its fellow phytonutrient quercetin.
According to a study published in the medical journal Current Cancer Drug Targets, “Plants rich in luteolin have been used in Chinese traditional medicine for treating various diseases such as hypertension, inflammatory disorders, and cancer. Having multiple biological effects such as anti-inflammation, anti-allergy and anticancer, luteolin functions as either an antioxidant or a pro-oxidant biochemically…”8
Luteolin is found most abundantly in:
Celery, green bell peppers, artichoke leaves, blueberries, carrots, rosemary, fresh thyme, fresh peppermint, and parsley.
Luteolin can also be found in other fruits, vegetables and herbs, but the aforementioned foods conta
in the highest concentrations.
How much do we need?
Selenium – 55 mg. For both men or women
Zinc – 11 mg. for men, 8 mg. for women. However, if you’re a strict vegetarian or a vegan, you may require as much as 50% more dietary zinc, because your body absorbs less zinc when you have a diet rich in plant-based foods.
Unfortunately, there is no RDA (recommended daily allowance) for any flavonoids, so there‘s no clear-cut amount of Quercetin or Luteolin you should aim for… It’s best to aim for a percentage of raw food intake. for example (and this is just an example), if 50% of your total daily calorie intake comes from raw fruits and vegetables you could be fairly certain that you were getting enough phytonutrients, of all kinds, to reap the associated benefits.