The Many Roles of Zinc
In 1958, Dr. Ananda Prasad had a 21-year-old patient from an Iranian village who presented as a prepubescent boy with underdeveloped sex organs and a lack of body hair. In 1963, his team discovered that this was due, in large part, to a zinc deficiency. This led to the first Recommended Daily Allowance (RDA) for zinc being established a decade later.
The many roles of zinc
Since then, we have discovered the many benefits of zinc for the body. It helps vitamins A and D, as well as a number of hormones (sex, stress, and thyroid), do their job. Zinc activates many enzymes that, in turn, provide antioxidant protection and immune support. Zinc is necessary for the production of nitric oxide, which helps control blood pressure. It is also vital for the composition of all proteins. This is huge since everything in the body is either made by proteins or is proteins. For example, proteins are needed to bind and remove heavy metals from the body.
How much do we need?
Health Canada sets the Recommended Daily Intake (RDI) at 9 mg per day for adult men and 8 mg per day for adult women. These amounts are considered sufficient to prevent deficiencies in most healthy adult individuals. However, the lack of sensitive indicators of zinc nutritional status in humans makes it difficult to determine the level of zinc intake most likely to promote optimal health. Some experts argue that some individuals, particularly bodybuilders or those on a strict vegan diet, would not thrive at these levels.
Who might be deficient?
The World Health Organization (WHO) estimates that half of the world's population is at risk of zinc deficiency. Usually, the first sign of a mild zinc deficiency is dry skin. Classic symptoms of zinc deficiency include dry skin, severe acne, sore throat, and diarrhea (secondary to infection). These symptoms are related to zinc's important role in skin health and immunity. Although zinc levels can be measured by blood test, current methods are too rudimentary to detect marginal deficiencies. The following populations and disease states may put individuals at higher risk of deficiency due to reduced dietary intake, absorption, retention or loss, and/or increased need:
- Diabetics
- Alcoholics
- People with digestive disorders (Crohn's disease, celiac disease, short bowel syndrome)
- People with persistent diarrhea or vomiting
- Vegans/vegetarians
- People with an unbalanced diet who consume processed foods (e.g., excess sugar, fat, or alcohol)
- Pregnant or breastfeeding women
- Infants/adolescents
- Other individuals (impaired methylation, rare genetic defects, etc.)
Diet is key
The most common reason for zinc deficiency is an unbalanced diet. The best sources of zinc are animal products (with the exception of cheese), especially oysters, red meat, and organ meats. For many reasons (environmental, health, and animal welfare), people are opting for plant-based diets. Vegetarian and vegan diets are rich in phytates, which are nutrient blockers that make minerals like zinc harder to absorb. A balanced, unprocessed, well-planned and well-executed plant-based diet should theoretically provide enough zinc. Soaking, sprouting, and fermenting nuts, seeds, and grains can help reduce phytate content.
Studies on zinc
Numerous clinical trials have proven that zinc supplements can help treat various diseases, particularly those caused or worsened by a deficiency. Below are some of the clinically validated uses of zinc supplementation:
- Zinc deficiency
- Treatment-resistant depression
- Skin (acne, wound healing, psoriasis)
- Type II diabetes
- Delayed progression of age-related macular degeneration (AMD)
Caution: Taking large amounts of zinc (50 mg per day or more) for several weeks can impair copper bioavailability. When taking high doses of zinc for extended periods, it is considered good practice to maintain a zinc/copper ratio between 15 to 1 and 2 to 1.