NMU – 172 Zinc Deficiency, Immunity and Other Aspects of Zinc in Human Health
Lifestyle Medicine Update No 172 (September 9, 2020)
with Dr. James Meschino
Topic: Zinc Deficiency, Immunity and Other Aspects of Zinc in Human Health
Source: Nutrients (June 2017); Frontiers of Nutrition (2014); The Journal of Nutrition (2000), Nutrients (July 2017); Oregon State University
The importance of the mineral zinc in human health, including its role in optimizing immune function, is very much underappreciated by the average person, as well as by many health care professionals. Some people take zinc lozenges if they feel a sore throat coming on or experience the initial signs of cold symptoms. Some evidence suggests this may have some benefit but ensuring adequate zinc intake on a daily basis for the prevention of health problems, including respiratory infections, is the strategy that we should pay more attention to, according nutrition and immunity studies.
Without getting into too many details it is well established that optimal zinc intake is required for optimal function of our immune system, as it works to protect us against respiratory tract and other infections. So, it’s interesting to note that North American population studies show that at least 55% of adults do not ingest the amount of zinc per day that is recommended by government agencies. In many underdeveloped countries where daily nutrition is poor or the high intake of phytic acid fiber in cereal grains leads to more severe zinc deficiency, zinc deficiency is a leading cause of death. According to the WHO, zinc deficiency is currently the fifth leading cause of mortality and morbidity in developing countries, affecting one-third of the world’s population. Worldwide, zinc deficiency accounts for approximately 16% of lower respiratory tract infections, 18% of malaria, and 10% of diarrheal diseases.
While severe zinc deficiency is rare in developed countries mild to moderate deficiency is more common. Unlike the mineral iron, the body has no way of storing zinc to any appreciable degree, and thus, optimal daily intake is the required to maintain optimal tissue and circulating levels of zinc. In North America and in many developed countries 30% of elderly individuals are shown to have mild to moderate zinc deficiency. Other groups where marginal zinc deficiency is more common include Black Americans and Mexican Americans, premenopausal women of childbearing age, including females 12-19 years of age, who are very prone to zinc deficiency. It is recommended that adult males and non-pregnant adult females consume 15 mg of zinc per day. Studies show that adult males and females in North America average about 11 mg of zinc intake per day from food. Elderly individuals (over 71 yrs. of age) average about 8 mg. This chronic sub-optimal intake can lead to signs and symptoms of mild to moderate zinc deficiency, which is not uncommon in our society.
Signs and symptoms of marginal zinc deficiency include any combination of the following:
- Decreased immune function or compromised immune function (decreased natural killer cell lytic activity), decreased interleukin-2 activity of T-helper cells, decreased serum thymulin activity -required for maturation of T-lymphocytes)
- Decreased taste acuity
- Decreased dark adaptation
- Decreased lean mass
- Decreased wound healing
Think about what happens as people age, they complain of not being able to taste their food to the same degree as when they were younger (and may also lose their appetite as a result), they lose their lean mass and strength, they are more prone to infections (and the infections can become more severe) and wounds to their skin and bruises heal much more slowly and sometimes not at all. These signs and symptoms, which are often attributed to the normal aging process, are often indicators of an underlying zinc deficiency that can be corrected through proper nutrition and/or supplementation. By the way treating those skin wounds that often heal slowly, or not at all, with a topical zinc ointment has been shown to solve the problem in many cases. But the real problem was an internal zinc deficiency in the first place. However, I must caution you that taking high doses of zinc supplements can be dangerous leading to impaired immunity, copper deficiency, anemia and other serious problems, so the idea here is not to run out and purchase high dose zinc supplements, unless instructed to by your medical doctor.
What seems to be a reasonable solution to ensure adequate zinc intake each day, along with other nutrients that are often lacking in the diet from day to day, is to consider taking a simple multiple vitamin and mineral supplement each day. I say this because the 2017 NHANES report showed that 31% of the U.S. population is at risk for at least one vitamin deficiency or anemia, most commonly vitamin A, B6, folic acid and vitamin B12. These studies also showed the high prevalence of sub-optimal intake for the minerals, calcium, magnesium, and zinc, and in older individuals, sub-optimal intake of zinc and selenium were very prevalent and highly noteworthy. So, adequate zinc nutritional status is something to pay attention to each day to help keep your immune system firing on all cylinders.
Consuming a well-balanced diet is the starting place. Beyond that, you may want to consider the merits of using a multiple vitamin and mineral each day (or 5 times a week) as a safeguard measure to ensure adequate zinc intake, along with other vitamins and minerals of importance. As a final note, blood tests to ensure adequate zinc nutritional status in children and adults is reflected by a zinc blood plasma level of 100 ug/dl (plus or minus 10 ug/ml). Values below 80 ug/dl are considered in the mild to moderate deficient range. A severe zinc deficiency is reflected by a plasma zinc level below 50 ug/dl. Unfortunately, blood plasma zinc tests are not routinely done by a doctor during an annual physical exam and provincial and state health plans do not pay for zinc blood tests. If you want a zinc blood test you would have to request if from your doctor and be willing to pay for it out of pocket. In most cases it’s unnecessary to go to these lengths if you eat properly and consider using a standard multiple vitamin and mineral supplement on a regular basis, in my view.
I’ve included the references for this information in the text below.
Gammoh NZ et al. Zinc in infection and inflammation. Nutrients 2017 (June). 9(6):624 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5490603/
Prasad A. Zinc is an antioxidant and anti-inflammatory agent: it’s role in human health. Frontiers of Nutrition (Review Article) 2014. https://www.frontiersin.org/articles/10.3389/fnut.2014.00014/full
Briefel RR et al. Zinc intake of the U.S. population: Findings from the Third National Health and Nutrition Examination Survey, 1988-1994. The Journal of Nutrition 2000. 130(5):1367s-1373s https://academic.oup.com/jn/article/130/5/1367S/4686375
Bird JK et al. Risk of deficiency in multiple concurrent micronutrients in children and adults in the United States. Nutrients 2017 (June). 9(7):655 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5537775/
Micronutrient Inadequacies in the U.S. population: an overview. Oregon State University https://lpi.oregonstate.edu/mic/micronutrient-inadequacies/overview
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