Zinc

What is it?

Zinc is considered a trace mineral, which means the body only needs it in small amounts. However, it is required for just about 100 enzymes in the body to carry out their necessary chemical reactions to support a healthy life. Humans have anywhere from 1.5 to 2.5 grams of zinc stored in the skeletal muscle and bone. Zinc levels in the blood will not always correlate with dietary supplement use and may be affected by the time that blood is drawn. It’s important to note also that zinc will fluctuate in response to infections, changes in muscle breakdown due to weight loss or illness, and changes in the levels of steroid hormone in the body.

What other names is it known by?

Zinc is goes by several different names.

• zinc sulfate

• zinc oxide

• zinc citrate

• zinc picolinate

• zinc acetate

• zinc glycerate

• zinc monomethionine

• zinc gluconate

Absorption of zinc in the form of zinc citrate and zinc gluconate are similar, at approximately 61%. The absorption of zinc oxide is about 50%. Taking supplements that contain 25 mg of elemental iron or more at the same time as taking a zinc supplement may reduce the absorption of zinc. Of note, the iron added to enriched foods does not interfere with zinc absorption.

What does it do?

Zinc is required for many aspects of cellular metabolism. It’s required for 100 enzymes to work efficiently, enhances immune function, supports protein and DNA synthesis, plays a role in cellular signaling and division, and supports wound healing. It’s also plays a role in the ability to taste and smell!

In the gut, zinc is taken in from the foods eaten, dropped into the gastrointestinal tract, and reabsorbed in the lining of the gut. As zinc intake increases, the amount of absorption in the gut increases.

When it comes to gut health, zinc is a critical nutrient. Too much, or too little zinc can cause unhealthy shifts in the gut microbiome and lead to diarrhea and inflammation. Zinc also plays a role in maintaining the tight junctions between the epithelial cells in the gut, essentially strengthening the barrier that protects the body from everything in the gut. If that barrier breaks down or there are gaps between the cells, this is known as leaky gut. Leaky gut is considered a major player in the development of autoimmune diseases, digestive diseases, diabetes, arthritis, asthma, fibromyalgia, chronic fatigue syndrome, and others.

Those with existing gastrointestinal disorders like IBS, IBD, ulcerative colitis, Crohn’s disease, and those who have had bariatric surgery, may be at an increased risk for zinc deficiency. Possible reasons for this are due to malabsorption and inflammation. The challenge is that zinc deficiency may lead to gut disorders, which can lead to zinc deficiency. It’s therefore critical to work with a dietitian and medical doctor to ensure your zinc status is adequate, if you have any existing gut disorders.

6% of the total zinc in the body is located in the skin. In the skin, zinc functions to stabilize cellular membranes, support several important enzyme reactions, and participates in cellular turnover that is important for maintaining healthy skin. Zinc has been used topically to help prevent sunburns since the times of ancient Greece. In addition, zinc plays a critical role in helping to heal wounds. A deficiency of zinc may be associated with hair loss.

Where is it found?

The richest sources of zinc are seafood, meat, and fish. Zinc is available in plant foods such as beans, nuts, and whole grains, however bioavailability of the zinc in these foods is decreased because of their phytate content. Phytates are the storage form of phosphorus in plants and they bind minerals such as zinc in the intestine which decreases their absorption. The amount of zinc absorbed from foods can be anywhere from 5-50% depending on the amount of phytates consumed. Those at risk of a zinc deficiency are therefore vegans and vegetarians because the amount of phytate they consume is typically higher. It may be important, if you’re a vegan or vegetarian, to seek out supplements that contain zinc, or ensure you’re consuming foods that are fortified with zinc. Check with your dietitian to be sure.

Supplements are available that contain zinc however you may only need a zinc supplement if your diet is insufficient, or you have an absorption issue (such as a gut disease or you’re vegan or vegetarian). Check with your dietitian to be sure and consider getting a zinc blood test to confirm. While toxicity of zinc has not been observed from consuming zinc containing foods, it has been observed from consuming supplements containing zinc. Toxicity symptoms include nausea, vomiting, abdominal cramping, decreased appetite, diarrhea, and headaches. And, too much zinc may contribute to an imbalance of the gut microbiome, exacerbating the above symptoms. Again, check with your doctor and dietitian before starting a zinc supplement and to determine if you need extra zinc.

How much do I need?

Adequate intake in the US, the level assumed to ensure nutritional adequacy, is as follows.

How to get it in my daily diet?

Even though the addition of plant-based foods may decrease the absorption of zinc, it’s still important to consume a diet that includes a healthy number of plants and vegetables. Consider the below food suggestions for your meals and check with your dietitian and doctor on how to improve your zinc intake.

Breakfast: fortified breakfast cereal that’s low in sugar and includes 3+ grams fiber = 2.8 mg

Lunch: roasted pumpkin seeds on a salad = 2.2 mg

Dinner: 2 crab cakes = 6.4 mg

Total: 11.4 mg

References

Angelo, G. (2013). Minerals and Skin Health. Oregon State University, Linus Pauling Institute. Retrieved from https://lpi.oregonstate.edu/mic/health-disease/skin-health/minerals

Harvard T.H. Chan School of Public Health. (n.d.). The Nutrition Source: Zinc. Retrieved from https://www.hsph.harvard.edu/nutritionsource/zinc/

Skrovanek, S., DiGuilio, K., Bailey, R., Huntington, W., Urbas, R., Mayilvaganan, B., … & Mullin, J. M. (2014). Zinc and gastrointestinal disease. World J Gastrointest Pathophysiol, 5(4), 496-513. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4231515/pdf/WJGP-5-496.pdf

U.S. Department of Health & Human Services, National Institutes of Health, Office of Dietary Supplements. (2022). Zinc: Fact Sheet for Health Professionals. Retrieved from https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/