With a CDC estimate of 7% of Americans suffering from the flu this past month, it is a good time to identify some significant dietary influences on our immune function. Of course quality sleep, staying well rested, getting regular exercise and fresh air are all equally important. When it comes to food, there are some critical components to be mindful of and reducing sugar intake may be one of the most essential practices. Skip the sweetened foods and beverages, including fruit juice where the vitamin C content gets outplayed by the high fructose content.
Slightly less important, but still effective for many, may be the elimination of gliadin, a specific type of gluten. Gliadin increases the permeability of the intestinal lining, allowing substances into circulation that can preoccupy our immune system. With approximately 75% of our immune cells residing within 1cm of the intestinal lining, it makes sense that we want to keep this “front” less of a drain on our immune resources.
Another helpful practice may be reducing our intake of tryptophan-rich foods. There is nothing wrong with the modest amount of chicken that may be in your grandmother’s chicken soup recipe (of course make this with rice or rice noodles and not wheat-based types), but larger amounts of tryptophan, generally from eating too much animal protein may feed the infection as viruses often benefit from an abundance of tryptophan and supplemental niacin. Skip the niacin-containing B vitamin when sick and be modest with foods such as chicken, turkey, cheese, and meats.
Many nutrients are pivotal in helping support various aspects of the immune response. The importance of these coupled with the large number of Americans that are deficient in one or more micronutrients, creates a list of potentially helpful foods. Aim to include what you can from the list below, hopefully replacing the sugar, gliadin, and foods that challenge the immune system along the way.
Cashews. Many people have lower than effective immune function due to zinc deficiencies. Zinc can be difficult for some people to find in their diet, especially with the exclusion of meat and fish. Cashews are an exceptional source from the plant world and they are also well balanced with respect to copper. A handful of cashews per day provide a major percentage of our daily zinc needs and may be helpful in supporting better immune function.
Green tea. Rich in numerous anti-viral compounds, this type of tea can help us stay hydrated (a fundamental component of fighting infection) as well as helping turn the tide in our favor. Look for less processed, higher quality Sencha or Matcha green teas for the highest alkylamine and therefore higher anti-viral properties. Do not boil the tea but add very hot water (best at 185F) to the green tea and steep for 3-5 minutes.
Vitamin D. White blood cells have Vitamin D receptors on their surface and these receptors require vitamin D interaction for an effective immune response. Low levels of vitamin D undermine our immune system’s efforts and supplementation or significant sunlight exposure, in those areas of the US where possible, is required to improve immune function. Consider supplementing so that blood levels can reach a desirable target range of 45-60 ng/mL. At this level, most individuals will have more vitamin D receptor stimulation and better white blood cell activity.
Grapefruits/Lemons/Tangerines. These citrus fruits are among the best sources of vitamin C and contain very little sugar, specifically fructose, in comparison to many other fruits. Regular consumption of vitamin C during infections does appear to help the immune system produce a more effective counter attack. These foods offer considerably more than just vitamin C, containing bioflavonoids and a wide variety of anti-inflammatory polyphenolics as well.
Sea vegetables. Dulse, kelp, alaria and other types of seaweed are the best sources of iodine. Iodine is needed by our white blood cells when they are destroying viruses and/or virally infected cells. Rather than adding large quantities of iodized salt, a small amount (one tablespoon on most cases) of a dried sea vegetable contributes significant iodine to our body’s immune system and its efforts of bringing infection under control.
Eat, drink, and be well!
~ John Bagnulo MPH, PhD.