Zinc - a powerhouse micronutrient
Most of the discussion around nutrition focuses on the macronutrients; the big parts of our diet: the proteins, the fats, the carbs...even the vitamins sometimes. But, we often forget about the little pieces that are essential for our bodies to function well.
Let's talk about zinc. Zinc is a micronutrient; we only need relatively tiny amounts...but we NEED those tiny amounts! We are at risk of zinc deficiency not only if we are not eating enough zinc-rich foods, but also if our diets contain lots of cereal grains and/or legumes. These plants contain phthalates which act to bind up the zinc and prevent it from being absorbed well into the body. At especially high risk for zinc insufficiency are people following a vegetarian or vegan diet, the elderly, or people suffering from chronic diarrhea or kidney disease.
Why is zinc so important? First, let's look at the most extreme example. Acrodermatitis enteropathica is a rare genetic disease in which a zinc binding protein is malformed and does not function. Individuals with this condition develop impaired growth, immune system problems, patchy hair loss, severe skin rashes and diarrhea. Luckily, with zinc supplementation, these impairments can be reversed and the individual can live a normal life.
Less extreme zinc deficiencies can still cause problems in a number of conditions. It is important to consider if zinc plays a role.
One of the key roles that zinc plays is the regulation of the inflammatory immune response. When we get infected with a virus or bacteria, our bodies release inflammatory markers and churn out extra immune cells to fight off the invader. This is an important way we clear these infections. However, sometimes, the inflammation can get out of control and start causing problems. (Think: autoimmune diseases, atherosclerosis, digestive issues, skin rashes etc). Here is where zinc comes in. Zinc helps to down-regulate that inflammatory cascade and keep the inflammation from getting out of control. During acute inflammation in the body, zinc leaves the bloodstream and is shuttled into organs, especially the liver, to assist in this inflammation down-regulation. (As an added benefit of this process, removing zinc from the bloodstream helps sequester it from the purview of the microorganism invaders who would also benefit from a bit of zinc.) Studies have shown that during widespread infection in the body, people with zinc deficiency fare much worse than those with normal zinc levels and have higher risk for death.
Zinc helps the immune system in other ways too. Zinc helps in the development of a normal, healthy immune system. Adequate zinc levels during pregnancy are necessary for the development of a well-functioning immune system in the baby. Studies have demonstrated that zinc deficiency during pregnancy impairs the production of several proteins that are necessary for the formation of healthy immune cells. Too little zinc, and the T cell components of the immune system tend to differentiate into Th2 instead of Th1. Th2 cells are key drivers of allergic reactions. Yikes. We don't want that.
Without zinc's immune modulation, there can be an excess of inflammatory markers, such as IL-6, which can impair the response to vaccination.
Normally, sufficient levels of Zinc are passed through the breastmilk. However, if mom suffers a deficiency and the infant does not have enough zinc, it puts her at risk for development of autism spectrum disorders, as well as some other signs of zinc deficiency such as diarrhea, hair loss, impaired growth and skin rashes. Treatment is simple - zinc supplementation!
Zinc has also been linked to a variety of other diseases. Disturbed zinc balance in the brain has been linked to Alzheimer's disease. Zinc deficiency has also been linked to the development of certain cancers, multiple sclerosis, Ehlers-Danlos syndrome, schizophrenia and depression.
Zinc can also be helpful in the treatment of diarrhea. The World Health Organization (WHO) and UNICEF recommends use of zinc in treatment of children with acute diarrhea. Studies show that when zinc is incorporated into the treatment, there is a reduction in the duration and severity of diarrhea for up to three months! Interestingly, this study provides evidence that the zinc supplementation is helpful even in those without low zinc levels.
Ok. Great. Zinc can be helpful in a number of conditions. Now, where can I find it?
Zinc is found in a number of foods. The highest zinc content is found in oysters! Red meat and poultry are main sources of zinc for most Americans. Zinc is also found in some fortified cereals, whole grains and nuts. Remember the phthalates we mentioned earlier? Those phthalates in the grains impair the zinc absorption, so it's harder to get adequate amounts from vegetarian sources.
Examine your family's diet and make sure that it includes some zinc-containing foods. If you are concerned that there isn't enough, check with your doctor if zinc supplementation is right for you.
(PS: Good thing we are entering oyster season!). Cheers!
Bajait C, Thawani V. Role of zinc in pediatric diarrhea.Indian J Pharmacol. 2011;43(3):232-235. doi:10.4103/0253-7613.81495
Nistor N, Ciontu L, Frasinariu OE, Lupu VV, Ignat A, Streanga V. Acrodermatitis Enteropathica: A Case Report.Medicine (Baltimore). 2016;95(20):e3553. doi:10.1097/MD.0000000000003553
Wessels I, Maywald M, Rink L. Zinc as a Gatekeeper of Immune Function.Nutrients. 2017;9(12):1286. Published 2017 Nov 25. doi:10.3390/nu9121286