Zinc is an essential mineral that is critical for the function of hundreds of enzymes. Consequently, it plays many roles, including in antioxidant enzymes, brain function, and the immune system. Zinc is most commonly taken to reduce the duration of respiratory infections and the common cold.
Zinc is most often used for
Last Updated:September 27, 2023
Zinc is an essential mineral and has a multitude of biological roles because it is a functional component of over 300 enzymes that rely on zinc to be able to catalyze chemical reactions. Zinc also participates in the structure of important proteins and is involved in the regulation of gene expression.[1][2]
Zinc is obtained from the diet. Oysters contain substantially more zinc than any other food, although red meat (e.g., beef, pork) and poultry provide the majority of zinc in the American diet. Other good sources of zinc are legumes, nuts, and dairy products.[3] In some countries, the flours used in cereals are fortified with zinc.[4]
The potential benefits of supplementation with zinc are largely dependent on the individual’s zinc status. Therefore, supplementation with zinc is unlikely to provide a benefit if zinc levels are already adequate and the person is not zinc deficient.[5] One exception to this rule may be respiratory tract infections and the common cold, conditions in which supplementation with zinc has been shown to reduce the duration of illness.[6][7][8] In children, zinc may help prevent pneumonia.[9][10] However, further high-quality studies are needed to bolster the evidence in this field.
Supplementation with zinc has been shown to improve depressive symptoms[11][12] and markers of glycemic control and blood lipids, particularly in people with chronic disease.[13][14][15] Supplementation with zinc may also improve severe acne, but higher-quality trials are needed to bolster the current evidence.[16][17]
In the short term, consuming zinc in excess of the recommended upper limit (40 mg/day)[1] can result in gastrointestinal symptoms (e.g., abdominal pain, nausea, vomiting, diarrhea).[1][18] In the long term, excessive zinc intake has been associated with copper deficiency and iron deficiency, as well as suppression of the immune system.[19][20][21] Also, the application of intranasal zinc has been reported to cause a loss of smell in some people.[22]
The potential benefits derived from supplementation with zinc seem to be at least partly attributable to zinc’s anti-inflammatory and antioxidant properties.[2][23][24][25]
Adequate dietary intake of zinc is essential for proper growth and development during pregnancy and throughout infancy, childhood, and adulthood.[2][26] Additionally, zinc is required for normal development, activity, and function of both innate and adaptive immune cells;[19][27] proper function of pancreatic beta-cells and glucose uptake;[28] and spermatogenesis and normal sperm physiology (e.g., sperm motility).[29]
In the brain, zinc ions inhibit N-methyl-D-aspartate (NMDA) receptors,[30] which is relevant to depression because this condition is characterized by elevated glutamatergic neurotransmission (to which NMDA receptors contribute).[31] Zinc may also benefit depression by increasing brain-derived neurotrophic factor levels.[32][33]
Zinc supplements vary in their dosages from 5–10 milligrams (mg) up to 25–45 mg, and sometimes higher. Dosages in the lower range are typically used as a daily preventative, whereas dosages in the higher range are typically used to treat chronic conditions and zinc deficiency.
Zinc supplements contain different forms of zinc. Each of these forms contains different amounts of elemental zinc, which refers to the weight of the zinc molecule by itself, for example:
This can be confusing, but most zinc product labels indicate the elemental weight of zinc that each dose provides. For example, if a label says “Zinc (as picolinate) 50 mg”, this means that each dose provides 50 mg of elemental zinc.
When it comes to increasing your testosterone, quality sleep, physical activity, and weight management come first. A few supplements can help sustain healthy testosterone levels, but most supplements marketed as testosterone boosters don't work, though some can make you believe they do by boosting your libido.
Testosterone is an androgen, a male sex hormone, though women need it too. In men, low testosterone has been associated with low libido[72] and poor health outcomes, such as the development of metabolic syndrome.[73] In men and women, low testosterone has been associated with depression.[74][75]
Middle-aged[76] and older[77] men see their testosterone levels decrease by 0.4% to 1.6% per year, and many are the men who experience lower-than-average levels even in their 30s.[78] Fortunately, quality sleep, physical activity, weight management, magnesium, zinc, and vitamin D can all help sustain healthy testosterone levels.
To optimize your testosterone levels, you don’t only need the proper amounts of vitamins and minerals; you also need to sleep well, exercise, and keep a healthy weight.
Lack of sleep causes numerous health issues. Notably, it decreases testosterone production[79][80][81][82][83] and facilitates fat gain[84] (and we’ll see that fat gain itself can impair testosterone production). Getting enough quality sleep is so important that we will be publishing an article on that soon.
Resistance training can raise testosterone levels for 15–30 minutes post-exercise.[85][86] More importantly, it can benefit testosterone production in the long run by improving body composition and reducing insulin resistance.[85]
Overtraining, however, is counterproductive. Prolonged endurance exercise especially can cause your testosterone to drop.[87][88] Ensuring adequate recovery time will help you receive the full benefits of physical activity.
Weight gain and the associated chronic diseases, such as cardiovascular disease and type 2 diabetes,[89][90][91] are strongly linked to decreases in testosterone, particularly in middle-aged and older men.
If you gain weight (as fat), your testosterone production drops. Fortunately, if you lose weight, your testosterone production can climb back up.
Adapted from Grossmann and Matsumoto. J Clin Endocrinol Metab. 2017.[92]
As this figure shows, observational studies have seen consistent results: in people who are overweight or obese, the greater the weight loss, the greater the testosterone increase.[89]
These results have been echoed in clinical trials. A meta-analysis of 24 RCTs looked at weight loss caused by diet or bariatric surgery:[93] In the diet studies, the average 9.8% weight loss was linked to a testosterone increase of 2.9 nmol/L (84 ng/dL). In the bariatric-surgery studies, the average 32% weight loss was linked to a testosterone increase of 8.7 nmol/L (251 ng/dL).
You need not lose huge amounts of weight to see a bump in testosterone levels, either: a 5% loss in weight can increase total testosterone by 2 nmol/L (58 ng/dL).[94]
Quality sleep, physical activity, and weight management support healthy testosterone levels, and they’re synergistic: If you lack sleep, you find it harder to exercise and easier to gain fat. If you exercise, you find it easier to sleep and to keep a healthy weight. If your weight is healthy, you find it easier to exercise and easier to sleep.
If you want to know more about the lifestyle-testosterone connection, check out our infographic and article here.
Only a few supplements have been shown to benefit testosterone production. Among those, the evidence mostly supports vitamin D and zinc, followed by magnesium. Two caveats should be kept in mind, however:
Supplementing with a vitamin or mineral is likely to help you only if you suffer from a deficiency or an insufficiency in this vitamin or mineral.
Correcting a deficiency or an insufficiency is more likely to raise your testosterone levels if they are low.
Vitamin D helps regulate testosterone levels.[95][96] Ideally, you would produce all the vitamin D you need through sunlight exposure, but if you live far from the equator, have dark skin, or simply spend most of your time inside, you may need to complement your own production with the help of foods or supplements.
In Canada and the United States, the Recommended Daily Allowance (RDA) for vitamin D falls between 400 and 800 IU (International Units).[97] These amounts, which have been criticized as too low by some,[98][99] are attainable from only a few food sources, which is why vitamin D has become a popular supplement.
| AGE | MALE | FEMALE | PREGNANT | LACTATING |
|---|---|---|---|---|
| 0–12 months | 400** | 400** | — | — |
| 1–13 years | 600 | 600 | — | — |
| 14–18 years | 600 | 600 | 600 | 600 |
| 19–50 years | 600 | 600 | 600 | 600 |
| 51–70 years | 600 | 600 | — | — |
| >70 years | 800 | 800 | — | — |
* 40 IU = 1 mcg | ** Adequate intake (AI)
Reference: Institute of Medicine. Dietary Reference Intakes for Adequacy: Calcium and Vitamin D (chapter 5 in Dietary Reference Intakes for Calcium and Vitamin D. The National Academies Press. 2011. DOI:10.17226/13050)
Zinc deficiency can hinder testosterone production.[54][100] Like magnesium, zinc is lost through sweat,[101] so athletes and other people who sweat a lot are more likely to be deficient. Although dietary zinc is mostly found in animal products, zinc-rich foods include some grains and nuts.
| AGE | MALE | FEMALE | PREGNANT | LACTATING |
|---|---|---|---|---|
| 0–6 months | 2* | 2* | — | — |
| 7–12 months | 3 | 3 | — | — |
| 1–3 years | 3 | 3 | — | — |
| 4–8 years | 5 | 5 | — | — |
| 9–13 years | 8 | 8 | — | — |
| 14–18 years | 11 | 9 | 12 | 13 |
| 19+ years | 11 | 8 | 11 | 12 |
* Adequate Intake (AI) Reference: Institute of Medicine. Zinc (chapter 12 in Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. The National Academies Press. 2001. DOI:10.17226/10026)
Consuming much more than your RDA[1] can be harmful. In the short term, high doses can cause nausea[18] and vomiting.[102] In the long term, they can lead to a copper deficiency.[103][104]
In males with low magnesium levels and low testosterone levels, an increase in magnesium intake can translate into an increase in testosterone production,[105] both directly and (since one of magnesium’s functions in your body is to help convert vitamin D into its active form[106]) indirectly.
While more common in the older population,[107] magnesium deficiency isn’t unknown in younger people (notably athletes,[108] since, link zinc, magnesium is lost through sweat[101][109][110]). Yet getting your RDA should be easy: magnesium-rich foods are numerous and can fit all kinds of diets.
| AGE | MALE | FEMALE | PREGNANT | LACTATING |
|---|---|---|---|---|
| 0–6 months | 30* | 30* | — | — |
| 7–12 months | 75* | 75* | — | — |
| 1–3 years | 80 | 80 | — | — |
| 4–8 years | 130 | 130 | — | — |
| 9–13 years | 240 | 240 | — | — |
| 14–18 years | 410 | 360 | 400 | 360 |
| 19-30 years | 400 | 310 | 350 | 310 |
| 31–50 years | 420 | 320 | 360 | 320 |
| >51 years | 420 | 320 | — | — |
* Adequate intake (AI)
Reference: Institute of Medicine. Magnesium (chapter 6 in Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. The National Academies Press. 1997. [111])
If you still feel the need to supplement, keep in mind that supplemental magnesium is more likely than dietary magnesium to cause adverse effects, which is why the FDA fixed at 350 mg the Tolerable Upper Intake Level for magnesium supplementation in adults. Also, you may want to avoid magnesium oxide: it has poor bioavailability (rats absorbed only 15% in one study,[112] and humans only 4% in another[113]) and can cause intestinal discomfort and diarrhea.
Numerous products are advertised as testosterone boosters, but the vast majority don’t work, though some can make you believe they do by boosting your libido. Maca, for instance, can enhance libido without affecting testosterone.[114][115][116][117]
Maybe the most popular “testosterone booster” is D-aspartic acid (DAA, or D-aspartate). DAA did increase testosterone levels in two studies, one that used 2.66 g/day[118] and the other 3.12 g/day,[119] but two later studies found no increase with 3 g/day,[120][121] and the latest even noted a decrease with 6 g/day.[120]
Eat a healthy, balanced diet, so as to avoid nutritional deficiencies. If your testosterone levels are low, pay attention to your intakes of vitamin D, zinc, and magnesium. Be skeptical of supplements marketed as testosterone boosters; there’s a good chance the only thing these supplements will boost is their manufacturers’ bottom lines.
The interventions discussed in this article will work best for men with low testosterone, but they can also help men with normal testosterone to sustain their levels, year after year.
Supplements can help, but they can’t replace a healthy lifestyle. In order to optimize your testosterone production, make sure you get enough quality sleep on a daily basis, incorporate some resistance training into your workout program, and monitor your weight.
Try to get enough vitamin D, zinc, and magnesium through your diet. However, if dietary changes prove insufficient, supplementation can help make up the difference.
Not all testosterone deficiencies can be fixed through lifestyle or supplement interventions. It may be prudent to speak with your doctor if the options discussed above do not yield sufficient results.
Error in dosage section
We wrote in the dosage section that zinc citrate was 11% elemental zinc, by weight. Because there are three zinc atoms per molecule of zinc citrate, it's actually closer to 34%.
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Tweak to relationship between zinc and ADHD
The wording of the effect of zinc supplementation on ADHD was slightly modified. It now says that there is a slight chance zinc may help with ADHD symptoms, but the research on this topic isn't consistent.
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FAQ and database update
We added newly published studies to our FAQs and database.
