Selenium vs Zinc: What to Choose and for Whom
On the shelf of a sports nutrition store, jars of selenium and zinc stand side by side, and a person who wants to "support immunity" or "hormones" often does not know which of them they actually need. The editorial team has put together a practical guide: who should think about zinc, who about selenium, when a combination is appropriate, and when neither supplement is needed.
Where to start the choice
The first rule the editorial team advises adopting: a mineral is chosen for a specific reason, not for the general idea of "just to have it". Both selenium and zinc have a relatively narrow safety corridor, so taking them without need may not merely be pointless but may also create new problems — from secondary copper deficiency to selenosis.
The second rule is to assess the diet first. A person who eats meat, fish, eggs and dairy several times a week most likely gets enough of both trace elements. Restrictive diets, vegetarianism, prolonged calorie deficit and some intestinal diseases, on the other hand, substantially change the picture.
The third rule is to take into account what is already in other supplements. Zinc and selenium are included in most multivitamins, "men's" formulas, and complexes for skin and hair, and zinc is also in ZMA. The total dose from several jars easily approaches the tolerable upper limit, even if each product on its own seems "safe".
Finally, it is worth honestly answering yourself what you expect. Neither of these minerals works as an anabolic stimulant or a testosterone "booster" in a person without a deficiency. Their real benefit is to close a gap in nutrition, and the choice should be made precisely for that task.
Who is more often short of zinc
Zinc deficiency in developed countries is rarely severe, but moderately reduced status occurs fairly often in certain groups. The main factor is a diet with a large share of whole grains and legumes and little animal produce, since phytates reduce absorption of the mineral.
- Vegetarians and vegans— the US Institute of Medicine suggests they aim for an intake up to one and a half times the standard norm.
- Athletes with intense training loads— some zinc is lost through sweat, and the energy deficit during "cutting" reduces intake from food.
- People with gastrointestinal diseases— Crohn's disease, celiac disease, chronic diarrhea, the state after bariatric surgery.
- People who abuse alcohol— alcohol increases zinc excretion in the urine.
- Older people— because of a smaller appetite and reduced absorption.
What might a zinc shortage indicate? Frequent infections, slow wound healing, impaired taste, brittle nails, dermatitis, hair loss. However, these symptoms are non-specific and occur in dozens of other conditions, so they are no basis for self-diagnosis.
For a person with a diet rich in meat and seafood, separate zinc is usually not needed. The exception is a short course of zinc lozenges at the start of a cold: Hemilä's meta-analyses show a shortening of the duration of symptoms, though the data are heterogeneous and relate specifically to lozenges, not swallowed tablets.
Separately about men's health. Zinc is indeed needed for testosterone synthesis, and in a deficiency its correction can raise the hormone level. But in men with normal status, additional zinc, including in the form of ZMA, does not raise testosterone — this was shown by the study of Koehler and colleagues.
Who is more often short of selenium
Selenium status is determined primarily by geography: the mineral content of the soil passes into grain, vegetables and the meat of animals. European soils are generally poorer in selenium than the soils of some regions of North America, so in Europe average intake is often below the recommended level, as Rayman notes in his review.
The groups at risk of insufficient status include people on strict plant-based diets of local products, patients on long-term dialysis or parenteral nutrition, and people with severe malabsorption. Moderately reduced status has also been described in older people.
A special situation is thyroid disease. The selenoprotein deiodinases take part in the metabolism of thyroid hormones, and the gland has one of the highest selenium concentrations in the body. However, the question of taking selenium in autoimmune thyroiditis or Graves' disease is decided by an endocrinologist, not a sales assistant.
Who definitely should not add selenium without need? People who already get enough of it from food, especially if they regularly eat Brazil nuts. The SELECT study showed that 200 mcg of selenomethionine per day did not protect men with normal status against cancer, and in the selenium group there was a trend toward more frequent type 2 diabetes.
| Situation | Zinc | Selenium |
|---|---|---|
| Vegan diet | Often appropriate | Depends on the region the products come from |
| A cold in the first days | Lozenges — there is an evidence base | No proven effect |
| Thyroid diseases | Not the first choice | Only by decision of an endocrinologist |
| An ordinary mixed diet | Usually not needed | Usually not needed |
| Intense training + calorie deficit | May be appropriate | As part of a multivitamin |
How to assess status and choose a form
For zinc the most common test is the concentration in serum or plasma. It has limitations: the level drops during inflammation, after eating, and depends on the time of day. Blood is therefore best drawn in the morning on an empty stomach and the result interpreted together with a doctor, taking symptoms and diet into account.
Selenium status is assessed by the concentration of selenium in plasma or serum, less often by the activity of glutathione peroxidase or the level of selenoprotein P. For everyday practice a simple blood selenium test is usually sufficient, if a doctor considers it warranted.
If the decision to take a supplement is made, easily absorbed organic forms — citrate, gluconate, bisglycinate, picolinate — perform well for zinc. For most adults it is appropriate to stay within limits that, together with food, do not exceed the tolerable upper limit of 40 mg per day. Zinc is better not taken on an empty stomach if nausea occurs.
For selenium a reasonable intake is considered to be a range comparable to the daily norm — tens of micrograms, not hundreds. The total intake from food and supplements should not approach the upper limit of 400 mcg. Selenomethionine and selenized yeast are absorbed very well, so there is no need to "compensate" for low bioavailability with high doses.
Combinations, interactions and typical mistakes
Can selenium and zinc be taken together? Yes, there is no direct competition for absorption between them, and most multivitamin complexes contain both trace elements. A combination makes sense, for example, for a vegan from a region with poor soils or for a person in a prolonged energy deficit.
Zinc, on the other hand, competes with copper and, at high doses, with iron. Prolonged intake of zinc at doses approaching or exceeding the upper limit without copper can lead to secondary copper deficiency with anemia and neurological disturbances. That is precisely why in quality complexes zinc is combined with a small amount of copper.
Zinc reduces the absorption of some antibiotics — tetracyclines and fluoroquinolones — as well as penicillamine. An interval is needed between taking these drugs and zinc, and it is worth checking it with a doctor or pharmacist. For selenium, fewer clinically significant interactions with common drugs have been described, but during treatment of oncological diseases the intake of antioxidants is discussed with an oncologist.
Typical mistakes the editorial team encounters in readers' questions: taking ZMA, a multivitamin and separate zinc in parallel; eating a handful of Brazil nuts daily on top of a selenium supplement; "courses" of high zinc doses to raise testosterone. In all these cases the total dose easily goes beyond the safe range.
Editorial conclusions
Zinc is more often needed by vegetarians, people with intestinal diseases, those who spend a long time in a calorie deficit, and also as a short course of lozenges at the start of a cold. Selenium is needed primarily by people at risk of low status because of their region of residence, a limited diet or medical conditions.
For a person with a balanced mixed diet, neither supplement is most likely needed, and a multivitamin closes possible gaps in safe doses.
The main rule of choice is to count the total dose from all sources and not go beyond the tolerable upper limits. In case of doubt it is worth taking tests and discussing the result with a doctor.
To understand the topic more deeply, the editorial team recommends reading our pieces "Selenium or Zinc: What's the Difference", a review of the ZMA complex and an article on copper and its interaction with other minerals.
References
- Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press; 2001.
- Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: National Academy Press; 2000.
- Rayman MP. Selenium and human health. Lancet. 2012;379(9822):1256–1268.
- Lippman SM, Klein EA, Goodman PJ, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2009;301(1):39–51.
- Hemilä H. Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage. JRSM Open. 2017;8(5).
- Koehler K, Parr MK, Geyer H, et al. Serum testosterone and urinary excretion of steroid hormone metabolites after administration of high-dose zinc supplementation. Eur J Clin Nutr. 2009;63(1):65–70.
- Maughan RJ, Burke LM, Dvorak J, et al. IOC consensus statement: dietary supplements and the high-performance athlete. Br J Sports Med. 2018;52(7):439–455.
Andriy Melnyk
A strength-sports coach and author of programs for beginner and intermediate levels. Writes about training planning.
