The discovery of zinc and its importance for human health wasn’t discovered until the late 1960’s [1]. Now, zinc is recognized as an essential mineral that's important to consume through food or supplements each day.

Zinc is an important component of over 100 metabolic reactions in the body, and helps maintain a healthy immune system, makes and repairs DNA and is even needed to help us taste and smell [2].

How much zinc do I need per day?

The amount of zinc you need per day depends on your sex and your age. Health officials determine requirements for zinc based on population studies, where the amount is estimated to meet the needs for 98% of healthy individuals.

If you live with a chronic condition or take certain medications, your zinc needs can be higher or lower.

The recommended daily intakes for zinc for healthy adults over the age of 18 are [3]:

• 7 mg per day for women
• 5 mg per day for men

Causes of Zinc Deficiency

Not getting enough zinc through diet

While zinc is found widely in many animal-based foods, including red meat, poultry, fish and seafood, excluding these foods regularly or following a vegetarian or vegan diet can increase your risk of zinc deficiency [2].

This is because the bioavailability of zinc in plant-based foods is significantly lower than animal-based foods. In other words, zinc from plants is not absorbed as well as zinc from animal foods. As such, if you follow a vegan or vegetarian diet you may require 50% more zinc than those who eat animal foods [2].

If you follow a vegan or vegetarian diet or regularly exclude animal foods, try and reduce the amount of phytates you consume in your diet. Phytates bind to zinc, decreasing its absorption in the body. Beans, grains and nuts & seeds are rich in both zinc and phytate. To remove the phytates and keep the zinc, let these foods soak in water for several hours before cooking.

In addition, older adults have been found to not get enough zinc each day, regardless of the diet they follow. In one national survey, it was estimated that up to 45% of adults over the age of 60 do not meet their recommended needs for zinc each day [4]

Consuming too much alcohol

While having a few glasses of wine per week with dinner has health benefits, chronic consumption of alcohol can cause serious nutrient deficiencies, including zinc deficiency.

About 30-50% of chronic alcohol consumers or alcoholics have zinc deficiency [5]. This is because alcohol will decrease the absorption of zinc in the digestive system while increasing zinc losses in the urine [5].

People who chronically consume too much alcohol also often replace healthy foods with alcoholic drinks, decreasing their overall zinc intake.

Medical conditions and medications

The relationship between medical conditions and zinc deficiencies may be bi-directional. This means that a medical condition could increase the risk of zinc deficiency, while zinc deficiency may increase the risk of a medical condition.

The following medical conditions are associated with lower levels of zinc [2].

• Gastrointestinal disease
• Diarrhea
• Sickle cell disease
• Autoimmune diseases
• Liver disease
• Alcoholism

The following medications and supplements can interfere with the absorption or increase the losses of zinc [2]:

• Thiazide diuretics
• Antibiotics
• Iron supplements

Signs & Symptoms of Zinc Deficiency

As up to 45% of older adults may not get enough zinc each day, it’s important to monitor for signs and symptoms of zinc deficiency.

Normal levels of zinc in the blood range from 0.66 to 1.10 mcg/ml.  Any values below 0.66 mcg/ml could indicate a zinc deficiency [6].

Early signs & symptoms of zinc deficiency

• Loss of appetite
• Impaired immune function
• Fatigue and weakness

Serious signs & symptoms of zinc deficiency

• Hair loss
• Diarrhea
• Weight-loss
• Impaired taste and smell

If you experience any of the above symptoms, it’s important to speak to your doctor about zinc deficiency. It’s also important to note that symptoms like diarrhea, abdominal cramping and nausea/vomiting are signs of consuming too much zinc [6].

Can I test for zinc deficiency?

A doctor can perform a blood test to measure the amount of zinc present in your blood.

Your doctor or another health care professional should also perform a thorough assessment, including medical history, medications and diet history to confirm zinc deficiency. This is because zinc deficiencies can exist even if blood levels are normal due to the different ways zinc is distributed in the body [7].

What foods should I be consuming each day to get enough zinc?

The recommended daily intake for zinc, from both foods and supplements, ranges from 7-9.5 mg per day.

Some of the best sources of zinc include:

• Oysters (30g): 74 mg or 900% DV
• Beef roast, cooked (30 g): 7 mg or 85% DV
• Chicken, cooked (30 g):4 mg or 33% DV
• Chickpeas, soaked and cooked (125 ml):3 mg or 16% DV
• Cashews (10g): 6 mg or 20% DV
• Cheese, swiss (10g): 2 mg or 14% DV

 

 Bibliography

 

1. Prasad, A. S. (2013). Discovery of human zinc deficiency: its impact on human health and disease. Advances in nutrition, 4(2), 176-190.
2. National Institutes of Health. (2020, July 15). Zinc. Dietary Supplement Factsheet. https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/
3. Public Health England. (2016, August 01). Government Dietary Recommendations. Government recommendations for energy and nutrients for males and females aged 1 – 18 years and 19+ years. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/618167/government_dietary_recommendations.pdf
4. Ervin, R. B., & Kennedy-Stephenson, J. (2002). Mineral intakes of elderly adult supplement and non-supplement users in the third national health and nutrition examination survey. The Journal of nutrition, 132(11), 3422-3427.
5. Kang, Y. J., & Zhou, Z. (2005). Zinc prevention and treatment of alcoholic liver disease. Molecular aspects of medicine, 26(4-5), 391-404.
6. Mayo Clinic Laboratories. (2021, January 01). Zinc Serum. Mayo Clinic Laboratories. https://www.mayocliniclabs.com/test-catalog/Clinical+and+Interpretive/8620#:~:text=Normal%20serum%20zinc%20is%200.66,is%20of%20minimal%20clinical%20interest.
7. Wieringa, F. T., Dijkhuizen, M. A., Fiorentino, M., Laillou, A., & Berger, J. (2015). Determination of zinc status in humans: which indicator should we use?. Nutrients, 7(5), 3252-3263.