Zinc deficiencies are often prevalent in developing countries, but an Oregon State University (OSU) study showed that 12% of Americans might be at risk of having low zinc levels, while as many as 40% of the US’s elderly population could be at risk for zinc deficiencies.
Zinc consumed through food and supplements is absorbed in the small intestine, but the NIH states diets consisting of high amounts of whole-grain breads, plant seeds, and cereals (foods with phytic acid) can inhibit a body’s absorption of zinc, even when the diet includes the recommended daily values of zinc. To combat this, many whole grains, cereals, and common foods are now fortified with zinc.
Since over 100 cellular processes that occur regularly throughout a human body require zinc, it comes as no surprise that it plays a vital role in many functions. Zinc is present in many over-the-counter cold remedies as a natural way to support a healthy immune system. Furthermore, zinc is crucial to the proper growth and development throughout pregnancy, and even throughout development into early adulthood.
Zinc intake into cells in the body is also associated with their increased ability to repair damaged DNA. Inability to correct damaged DNA leads to a variety of disease states and health concerns, including uncontrolled cellular mutations and proliferations which is the definition of cancer.
The OSU study noted that in men, the prostate gland has some of the highest zinc concentrations of any organ. It also noted that prostate cancer, the second leading cause of death in men, is associated with decreased zinc levels in the prostate.
Poor nutrition and nutrient absorption contribute to the reduced zinc concentrations often found in older adults and may be a possible explanation for the increased risk of this population to develop infections and autoimmune diseases.
According to the NIH stunted growth, growth retardation, appetite loss, and decreased immunological functions are most commonly associated with zinc deficiency. An article by doctors Wessells and Brown in the 2012 PLOS journal studied developing countries and zinc deficiency and were able to correlate high occurrences of childhood stunting to areas with the worst zinc deficiencies.
In severe cases zinc deficiency can lead to hair loss, weight loss, reproductive tract abnormalities, diarrhea, delayed wound healing, and even temporary drops in IQ have been reported.
Although the body naturally compensates to dietary intake by absorbing more zinc in a low zinc diet and less zinc in a high zinc diet, too much zinc can still pose a serious threat. Nausea, vomiting, abdominal cramps, diarrhea, reduced immune response, decreased high-density lipoproteins and more are all adverse side effects the NIH states are associated with overexposure to zinc.
The recommended doses of Zinc vary depending on age, gender and if you are pregnant or lactating. According to table 1 in the NIH zinc fact sheet for health professionals the recommended daily allowances are as follows:
Table: Recommended Dietary Allowances (RDAs) for Zinc
|0–6 months||2 mg*||2 mg*|
|7–12 months||3 mg||3 mg|
|1–3 years||3 mg||3 mg|
|4–8 years||5 mg||5 mg|
|9–13 years||8 mg||8 mg|
|14–18 years||11 mg||9 mg||12 mg||13 mg|
|19+ years||11 mg||8 mg||11 mg||12 mg|
* Adequate Intake (AI)
Typically meats have the highest sources of zinc, with oysters having the most zinc per serving of any other food. Behind them, red meat, chicken, lobster, beans, dairy products (cheese, milk, yogurt) and nuts are also excellent sources of zinc.
Because of the nature of the foods that are high in zinc, vegetarians and vegans are especially at risk for zinc deficiency. The NIH also notes other at-risk groups include those with malabsorption syndrome, sickle cell, diabetes, digestive disorders and chronic diarrhea. Alcoholics also usually excrete more zinc in their urine, putting them at risk for zinc deficiencies as well.
While adult men require more zinc on average than women, women who are pregnant or lactating need more zinc to aid in the fetal development. In addition to eating foods that support meeting all nutritional requirements, zinc is also available in dietary supplements and some over the counter cold treatment and prevention options.
Currently, there are very few biological tests that accurately measure the amount of zinc a body is absorbing. Many tests can only measure blood zinc levels, which is not always a good representation of the intracellular zinc levels due to the cell’s homeostatic and osmotic mechanisms. To ensure that you are getting the recommended daily dose of zinc, be sure to eat a diet that includes foods with high zinc levels or consider supplementing your diet with a multivitamin.