Combining Selenium & Zinc Sensibly

Selenium and zinc are often mentioned in the same breath. Both are essential trace elements, both occur in the body only in tiny amounts, and both regularly come up together when it comes to the immune system, cell protection, or healthy skin and nails. No wonder many people wonder whether it makes sense to take them together, and what to watch out for when doing so.

The short answer: yes, selenium and zinc combine well. At typical amounts, they don't interfere with each other, and their roles in the body overlap in several places. As always, the right amount is what matters, because with these two trace elements in particular: more isn't better. In this guide, we take an objective look at why the combination makes sense, which dosages are sensible, and which upper limits you should keep in mind.

Selenium and Zinc Briefly Introduced

Zinc is one of the best-known trace elements and is involved in hundreds of enzyme reactions in the body. It plays a role in cell metabolism, cell division, skin, hair, and nails, as well as the immune system. The body can't store zinc, which is why a regular supply through diet is important. Good sources include meat, cheese, whole-grain products, legumes, and nuts. You'll find more background in our guide Zinc: Effects, Daily Requirement, and Recognising a Deficiency.

Selenium is considerably less well known, but just as essential. Among other things, the body needs it for certain enzymes that play a role in cell protection and thyroid metabolism. The selenium content of food depends heavily on how selenium-rich the soil is where it's grown. Soils in Europe are comparatively considered low in selenium, which is why selenium comes up more often here. Sources include fish, meat, eggs, nuts (especially Brazil nuts), and legumes. We cover how much makes sense in detail in the article Selenium: How Much per Day Makes Sense?

Why Selenium and Zinc Work Well Together

The most important reason for combining them lies in their complementary roles. Both trace elements are relevant to the immune system and to protecting cells, but they cover different building blocks in doing so.

Officially authorised claims exist for the immune system: selenium contributes to the normal function of the immune system and zinc contributes to the normal function of the immune system. Two trace elements that act on the same target, but contribute through different enzymes and processes. That's exactly what makes it sensible to consider them together.

When it comes to cell protection, both pull in the same direction too. Selenium and zinc each contribute to the protection of cells from oxidative stress. Oxidative stress arises when the body produces more reactive oxygen compounds than it can neutralise. Both trace elements are part of the body's own protective system that helps maintain this balance. The fact that two nutrients make the same contribution isn't a contradiction — if anything, it's an argument for making sure you're adequately supplied with both.

One additional point speaks for selenium: it has a role that zinc doesn't cover. Selenium contributes to normal thyroid function. The thyroid needs selenium for enzymes involved in the metabolism of thyroid hormones. Objectively speaking, that's a standalone reason why selenium has its place in a combination.

Because zinc and selenium are so often needed together, they also come up together in many other contexts, for example when it comes to nutrients for strong fingernails or beautiful skin, hair, and nails from within. They're also frequently mentioned together in topics such as male fertility.

How to Combine Selenium and Zinc Correctly

When combining them, it's less about an elaborate schedule and more about sensible amounts. Both trace elements can be taken together without any problem, ideally with a meal, which is gentler on the stomach. For zinc, we address the question of timing separately in the guide Zinc: With or Without Food?

More important than timing is the amount you take. The reference values from the German Nutrition Society (DGE) offer a useful guide:

• Selenium: the estimated value is around 70 µg per day for men and 60 µg per day for women. These amounts are therefore in the microgram range, i.e. thousandths of a milligram.
• Zinc: depending on the intake of plant-based inhibitors (phytate), the recommended value is around 11 to 16 mg per day for men and 7 to 10 mg per day for women. Zinc is therefore measured in the milligram range.

It's important to understand this difference in scale: selenium is dosed in micrograms (µg), zinc in milligrams (mg). If you're combining the two, don't mix up the figures. Sensible supplementation is guided by these reference values and by how well your diet already covers them. If you eat a lot of meat, fish, eggs, and whole grains, you're often already in a good range for both.

The upper limits are absolutely crucial. Germany's Federal Institute for Risk Assessment (BfR) has issued recommendations for maximum amounts in dietary supplements: a maximum of 45 µg of selenium per day and a maximum of 6.5 mg of zinc per day from supplements. These figures deliberately refer to the additional intake from supplements, because part of the requirement is already covered through diet. Sticking to these amounts keeps you comfortably within the safe range.

What You Should Watch Out For

Precisely because selenium and zinc are such potent trace elements, clear moderation applies to both. With selenium, the range between too little and too much is comparatively narrow.

Selenium upper limit: the European Food Safety Authority (EFSA) has derived a tolerable upper intake level (UL) of 255 µg per day for adults, based on all sources combined. Consistently, significantly higher amounts can lead to selenium overload, which can show up through symptoms such as brittle nails, hair loss, or garlic-like breath, among others. This is one reason why the BfR deliberately sets the maximum amount in supplements low.

Zinc upper limit: for zinc, the EFSA states a tolerable upper intake level of 25 mg per day for adults from all sources. Here too, consistently too much is not harmless.

Zinc and copper with long-term use: the most important point with prolonged zinc intake doesn't concern selenium, but copper. Higher amounts of zinc can inhibit the absorption of copper from food over time, because the two trace elements compete for the same absorption pathways in the gut. If you supplement zinc long-term in higher amounts, you should therefore keep an eye on the ratio to copper. We explain what that looks like in the guide Zinc and Copper: The Right Ratio. At moderate amounts within the BfR recommendation, this point is less critical, but it's still worth knowing about. The question of how long you should take zinc is closely related to this as well.

If you already take medication, have a thyroid condition, are pregnant, or are breastfeeding, it's best to discuss taking selenium and zinc with your doctor first. A blood test can also show whether there's actually a need in the first place.

An Honest Assessment

Selenium and zinc are a duo that makes sense. Both support the immune system and cell protection, selenium additionally brings the thyroid into play, and at typical amounts they get along without any problem. That makes this combination one of the more sensible ones if you're looking to supplement trace elements.

At the same time, honesty matters: dietary supplements don't replace a balanced diet, and with these two trace elements, more doesn't mean more benefit — sustained overdosing can actually cause harm. If you eat a varied diet, you often already cover selenium and zinc well. Supplementing is then mainly of interest for people whose intake falls short for particular reasons. If you do supplement, keep the amounts moderate, close to the reference values, and respect the upper limits. That way, you get the real benefit from the combination without overdoing it.