Tired of getting sick? Sometimes it's out of your control, but, in addition to basic hygiene, there are indeed steps you can take to reduce your chances of falling sick. It turns out there might be some truth to the age-old adage "you are what you eat."
Are you susceptible to getting the cold and flu a couple of times per year? Perhaps you travel a lot for work and end up with a blocked nose and sore throat after most flights. Or maybe for you its recurrent cold sores or styes that won’t seem to go away.
Stress plays a major role in reducing our immune system. In this context, there are two main types of stress to consider:
- Physical - such as overexertion and injury
- Mental - having an endless to-do list that you can’t keep on top of, or personal issues constantly weighing on your mind.
Stress has a detrimental effect on your body by weakening immune cells, specifically their proliferation and antibody production, thus increasing the bodies susceptibility to infection (8). But luckily there are things we can include in our diet in order to help our body. Take care of yourself with the following dietary tips.
Zinc is an essential mineral integral to maintaining the normal development and function of immune cells, in particular neutrophils, natural killer cells, B-cells and T-cells (1&2). Neutrophils and natural killer cells are part of the first line of defense, known as the innate immune system (3) and are essential in responding to invading pathogens. B cells and T cells help create antibodies as well as destroy infected cells. Therefore it’s pretty important to ensure we have zinc in our diets!
Zinc-containing foods include: oysters, beef, lamb, pork, chicken, spinach, pumpkin seeds, nuts, dark chocolate, beans and mushrooms.
2. Vitamin C
Unlike most mammals, humans do not have the ability to synthesize our own vitamin C, so we must obtain it from our diets. Vitamin C plays a role in the production and function of immune cells such as neutrophils, lymphocytes and phagocytes (4). White blood cells release free radicals in order to destroy pathogens, and as Vitamin C is an antioxidant it has been shown to protect leukocytes from self-inflicted oxidative damage. A 2017 meta-analysis showed that regularly administered vitamin C has shortened the duration of colds (5).
Get your vitamin C from: guava, red & green capsicum, kiwi fruit, oranges, strawberries, papaya, broccoli, kale, pineapple, grapefruit & lemon.
3. Vitamin A
Vitamin A is a fat-soluble vitamin involved in regulating the growth and differentiation of nearly all the immune cells in the human body (6). This includes immune cells in both the innate and adaptive immune systems (7). Vitamin A deficiency is shown to be linked to a reduced ability to resist infections.
Vitamin A-containing foods are: beef liver, carrots, sweet potato, pumpkin, mango, kale, spinach, broccoli, butter & eggs.
4. Vitamin D
Vitamin D is the only vitamin that can be synthesized in the skin after exposure to sunlight! Vitamin D in its active form is a powerful modulator and helps to strengthen our innate immune system (9). To get vitamin D from the sun just make sure you’re out in the sun for 15 minutes daily and avoid the peak hours of sunlight so that you don’t get burnt.
To get vitamin D from your food you need to eat cod liver oil, salmon, tuna, sardines, mackerel, eggs, mushrooms & foods fortified with vitamin D.
Iron deficiency is associated with impaired T-cell function & thus a reduced ability to terminate infected cells in the body (10). Excessive iron, on the other hand, is toxic for your body. Therefore adequate iron levels are critical for healthy immune function. Always check your serum iron levels with a doctor before taking iron supplements.
Get your iron from: beef, chicken liver, oysters, tuna, prune juice, spinach, Swiss chard, white beans, lentils, tofu, hazelnuts & cashews.
Tip: vitamin C containing foods help the absorption of iron, so try to combine the two!
6. B Vitamins
Each individual B vitamin exerts its own role within the body, however they also work together as a team. In relation to the human body, a B vitamin deficiency can lead to decreased antibody function, disruption of the barriers to infection and decreased immune cells.
In order to get enough B vitamins in your diet, make sure you’re eating: whole grains, asparagus, almonds, eggs, beef, chicken, legumes, avocado, brewer’s yeast, green leafy vegetables, sunflower seeds, salmon and sardines.
The active constituent of garlic, allicin, exerts an antibacterial effect and helps to fight off infection by stimulating white blood cells (11). A recent study showed that compared to placebo, those who consumed a garlic extract reduced the severity of their cold and flu by 61% (12). Add garlic to your stir-fries, soups, roasted vegetables, dips, marinades & dressings.
Mushrooms are well known for their ability to boost the immune cells. They do this by increasing the activity of white blood cells making them more aggressive, which is a great thing when you have an infection! (13). The Shiitake and Reishi mushrooms in particular are beneficial for immune health, add a handful to your scrambled eggs in the morning or to your salads and stir-fries.
These 8 nutrition tips should speed you up on your road to recovery. Obviously all of bodies react in different manners to various substances and nutrients, so you may have to do a bit of experimenting to figure out which of these tips work best for you. That being said, remember, even if you don't feel an immediate impact from what you eat, that doesn't mean the various vitamins and nutrients aren't working hard in the background to help you live a healthier and happier life.
If you would like help being prepared for or managing your colds and flus, book an appointment with Christina through her profile. You should also check out this other recent post by Christina that explains which foods are good to eat to soothe menstrual cramps (AKA period pain)..
We're also focusing on increasing access to primary care. Speak with a doctor online on RingMD. Why leave home to find a doctor if you don't have to? Avoid sick people in busy waiting rooms and skip the traffic jam. When appropriate, the doctor is able to prescribe medication and issue a medical certificate (MC) that can be delivered to your door. See this for tips to make the most out of your doctor consultation.
- Prasad, A. S. (2009). Zinc: role in immunity, oxidative stress and chronic inflammation. Current opinion in Clinical Nutrition and Metabolic Care, 12(6), 646-52.
- Kwon, D. I., & Lee, Y. J. (2017). Lineage differentiation program of invariant natural killer T cells. Immune Network, 17(5), 365-377.
- Selders, G. S., Fetz, A. E., & Bowlin, G. L. (2017). An overview of the role of neutrophils in innate immunity, inflammation and host-biomaterial integration. Regenerative Biomaterials, 4(1), 55-68.
- Leal, E., Zarza, C., & Tafalla, C. (2017). Effect of vitamin C on innate responses of rainbow trout leukocytes. Fish & Shellfish Immunology, 67(8), 179-188.
- Hemila, H. (2017). Vitamin C and infections. Nutrients, 9(4), 339-422.
- Bono, M. R., Tejon, G., Flores-Santibanez., F. Fernandez, D., Rosemblatt, M., & Sauma, D. (2016). Retinoic acid as a modulator of T cell immunity. Nutrients, 8(6).
- Raverdeau, M., & Mills, K. H. Modulation of T cell and innate responses by retinoic acid. Journal of Immunology, 192(7), 2953-8.
- Dhabhar, F. S. (2014). Effects of stress on immune function: the good, the bad and the beautiful. Immunologic Research, 58(2), 193-201.
- Lee, W.P., Willekens, B., Cras, P., Goossens, H., Martinez-Cacares, E., Bernemen, Z.N., Cools, N. (2016). Immunomodulatory effects of 1,25-Dihydrozyvitamin D3 on dendritic cells promote induction of T-cell hyporesponsiveness to myelin-derived antigens. Journal of Immunology Research, 5392623.
- Hassan, T.H., Badr, M.A., Karam, N. A., Zkaria, M., El Saadany, H. F., Abdel, Rahman, D. M., Shahbah, D. A., Al Morshedy, S., Fathy, M., Esh, A., & Selim, A. (2016). Impact of iron deficiency anemia on the function of the immune system in children. Medicine, 95(47), 5395.
- Patya, M, Zahalka, M.A., Vanichkin, A., Rabinkov, A., Miron, T., Mirelman, D., Wilchek, M., Lander, H., & Novogrodsky, A. (2016). Allicin stimulates lymphocytes and elicits an antitumour effect: a possible role of p21ras. International Immunology, 16(2), 275-81.
- Nantz, M.P., Rowe, C.A., Muller, C.E., Creasy, R.A., Stanilka, J.M., Percival, S.S. (2012). Supplementation with aged garlic extract improves both NK and γδ-T cell function and reduces the severity of cold and flu symptoms: a randomized, double-blind, placebo-controlled nutrition intervention. Clinical Nutrition, 31(3), 337-44.
- Dai, X., Stanilka, J.M., Rowe, C.A., Esteves, E.A., Nieves, C., Spaiser, S., Christman, M.C., Langkamp-Henken, B., & Percival, S.S. (2015). Consuming Lentinula edodes (Shiitake) Mushrooms Daily Improves Human Immunity: A Randomized Dietary Intervention in Healthy Young Adults. Journal of the American College of Nutrition, 34(6), 478-87.