Zinc is hands down one of the most important trace elements in our diet. From hormonal regulation and neurotransmitter function, through to immune system modulation and regulation of the senses. It is vital. Yet it is still one of the most deficient nutrients, along with selenium and magnesium, in our diet in this part of the World.
Whilst there can be many, in my own clinical experience, these three common signs point to a need for more zinc on your diet.
Frequent colds & hard to shift infections
Zinc is a key regulator of our immune system, influencing both the innate and adaptive branches of our immune system (Prasad, 2014). One specific role that zinc plays is that is codes genes in our white blood cells that then go on and regulate how those white cells respond to infection.
Deficiency in zinc can quickly manifest itself as an increased number of infections, particularly of the upper respiratory tract such as colds and flu (Read et al, 2019). Zinc also acts as an antiviral substance in its own right, helping to directly interact with pathogens that cause upper respiratory tract infections (Barnett et al, 2010). You know that I am very much in favour of supplements, and zinc supplementation has been shown in multiple trials to reduce the duration and the severity of the common cold (Hemila, 2011).
Impaired sense of taste
Zinc is a key play in the gustatory system too. It forms a key part of a protein called gustin which is vital for both the development and the regulation of the taste buds (Henkin et al, 1975). Zinc is the major co factor for this protein and as such facilitates its proper activity.
When there is a decline in gustin activity due to insufficient zinc, it leads to a condition known as hypoguesia, an impaired sense of taste (Heckmann et al, 2005). This decline in sense of taste is especially noticeable in salty and sweet flavour profiles, and zinc supplementation has been shown to improve this greatly (Stewart-Knox et al, 2005).
Reduced appetite
As is a key trend here, zinc is a cofactor in key appetite regulation hormones too, such as leptin and ghrelin. The major hormone that stimulates hunger, Ghrelin requires zinc for its secretion and its activation (Dardenne at al, 2002). Leptin, a key hormone in satiety signalling and feelings of fullness are disrupted by deficiency of zinc. Several studies have shown that zinc supplementation restores appetite and improves satiety regulation (Mantzoros et al, 1998).
Foods & Supplementation
Food first is always my motto, but is that even enough any more with the state of our food system? Who knows? The best food sources of zinc are seafood (especially oysters), beef, pumpkin seeds, walnuts, poultry and fish. Plus you will get a reasonable amount of zinc in whole grains too.
When it comes to supplements, we need to be aware that there is quite a dosage range. When fighting infection or if you are run down, then everyone can supplement at the 50mg per day mark. However, when it comes to long term intake, there is a big difference. Men, because it is so vital for our testosterone metabolism, need around 30mg a day. Women need only around the 15mg per day mark.
References
Barnett, J. B., Dao, M. C., Hamer, D. H., Kandel, R., Brandeis, G., Wu, D., ... & Meydani, S. N. (2010). Effect of zinc supplementation on serum zinc concentration and T cell proliferation in nursing home elderly: a randomized, double-blind, placebo-controlled trial. American Journal of Clinical Nutrition, 91(3), 163-168.
Dardenne, M., Pleau, J. M., Nabarra, B., Lefrancier, P., Derrien, M., Choay, J., & Bach, J. F. (2002). Contribution of zinc and other metals to the biological activity of the serum thymic factor. Proceedings of the National Academy of Sciences, 79(17), 5370-5373.
Hemilä, H. (2011). Zinc lozenges may shorten the duration of colds: a systematic review. The Open Respiratory Medicine Journal, 5, 51-58.
Henkin, R. I., Bradley, D. F. (1975). Gustin concentration changes relative to salivary zinc and taste in humans. Proceedings of the National Academy of Sciences, 72(3), 1007-1011.
Heckmann, S. M., Hujoel, P., Habiger, S., Friess, W., Wichmann, M., Heckmann, J. G., & Hummel, T. (2005). Zinc gluconate in the treatment of dysgeusia – a randomized clinical trial. Journal of Dental Research, 84(1), 35-38.
Mantzoros, C. S., Prasad, A. S., Beck, F. W., Grabowski, S., Kaplan, J., Adair, C., & Brewer, G. J. (1998). Zinc may regulate serum leptin concentrations in humans. Journal of the American College of Nutrition, 17(3), 270-275.
Prasad, A. S. (2014). Zinc: an antioxidant and anti-inflammatory agent: role of zinc in degenerative disorders of aging. Journal of Trace Elements in Medicine and Biology, 28(4), 364-371.
Read, S. A., Obeid, S., Ahlenstiel, C., & Ahlenstiel, G. (2019). The Role of Zinc in Antiviral Immunity. Advances in Nutrition, 10(4), 696-710.
Stewart-Knox, B. J., Simpson, E. E. A., Parr, H., Rae, G., Polito, A., Intorre, F., ... & Meunier, N. (2005). Taste acuity in response to zinc supplementation in older Europeans. British Journal of Nutrition, 93(1), 31-35.
