When to take Selenium | PlanYourVitamins.com

What is selenium good for?

Short answer: Selenium has potential benefits for antioxidants, cancer prevention, cardiovascular health, brain health, the immune system and thyroid function.

Selenium is one of several essential minerals that we need in order to survive. It supports our metabolism, immune system function and thyroid function, although the full range of benefits selenium offers is large.

On the other hand, a deficiency in selenium can result in an increased risk of disease, but thankfully selenium is found in many foods, and is also easily available in supplemental form for those who may be deficient.

Selenium functions as an antioxidant, reducing oxidative stress and boosting the immune system in order to defend the body from the chronic conditions that oxidative stress can cause, such as inflammatory diseases, stroke, heart disease, Alzheimer's disease and cancer, as well as premature aging.

Role in cancer prevention

In fact, a review of 69 studies that included over 350,000 participants concluded that high blood levels of selenium were directly associated with a lower risk of certain cancers, including breast cancer, lung cancer, prostate cancer and colon cancer.

Benefits for cardiovascular health

Likewise, a review of 16 studies including over 433,000 participants that suffered from heart disease found that selenium supplementation significantly decreased a key inflammatory marker associated with the condition. A further analysis of 25 studies found that a 50% increase in blood levels of selenium was associated with a 24% reduction in the risk of developing heart disease.

Benefits for brain health

Regarding Alzheimer's disease specifically, research shows that people who have lower blood levels of selenium have an increased risk of developing the disease, and it is known that diets rich in antioxidants like selenium, such as the Mediterranean diet, improve memory in people suffering from Alzheimer's disease.

One interesting study found that taking one single selenium-rich Brazil nut a day managed to improve speech and mental functions in patients that were suffering from mild cognitive impairment.

Role in thyroid function

Selenium is also very important for proper thyroid function, and thyroid tissue actually contains more selenium than any other tissue in the human body. The selenium is known to protect the thyroid against oxidative stress, and also plays a crucial role in our metabolism and hormone production.

A deficiency in selenium is linked to an increased risk of hypothyroidism, a condition where our own immune system attacks the thyroid, while selenium supplementation has been shown to improve symptoms in people that suffer from the disease.

When should I take selenium?

Short answer: Selenium is best taken on an empty stomach, at least 2 hours since the last meal and at least 30 minutes before the next meal.

Multiple foods are known to negatively affect the absorption of selenium, and some studies have shown that taking selenium on an empty stomach results in maximum absorption, although there is no specific time of day that appears to be optimal.

What does selenium combine well with?

Short answer: Selenium has been shown to work well together with beta-carotene, lycopene, piperine, saw palmetto extract, vitamin A, vitamin C, vitamin E and zinc.

Selenium with vitamin A, vitamin C or vitamin E, for increased absorption

The presence of certain nutrients can determine how much selenium we can absorb, with vitamin A, vitamin C, and vitamin E in particular associated with an enhanced absorption of the element. Vitamin E also serves to enhance selenium's antioxidant activity.

Selenium with beta-carotene, for antioxidant activity

Selenium's antioxidant properties are also known to be reinforced in the presence of beta-carotene.

Selenium with saw palmetto and lycopene, for prostate and urinary tract health

One study revealed that selenium, when combined with saw palmetto extract and lycopene, offered greater anti-inflammatory results in people that were suffering from reduced urinary flow, including benign prostatic hyperplasia (BPH), than when the supplements were taken individually.

Selenium with zinc, for cancer prevention

Both selenium and zinc have been documented for their efficacy in the prevention of cancer, and their combined supplementation is often recommended as a form of prophylactic against the disease, especially prostate cancer.

Selenium with piperine, for increased absorption

Piperine is the active ingredient in black pepper, and is known for its absorption-increasing properties when taken together with a variety of compounds, including selenium.

What should I avoid taking selenium with?

Short answer: Avoid taking selenium supplements at the same time as astragalus, B-complex, L-glutathione, vitamin B3, antacids, birth control pills, chemotherapy drugs or statins.

Avoid with niacin (vitamin B3)

Selenium is known to interact with niacin (vitamin B3), so it is advised to take these separately, at least three hours apart.

Avoid with astragalus

It is also known that some species of astragalus can naturally contain high levels of selenium, so you would be advised to avoid taking selenium supplements together with astragalus in order to avoid excess selenium intake.

Avoid with L-glutathione

Also, lower levels of glutathione are associated with an increased absorption of selenium, so it may be a good idea to take these separately.

Avoid with antacids, statins, birth control or chemo drugs

Selenium could potentially interact with other medicines and supplements, such as certain antacids, chemotherapy drugs, corticosteroids, statins, or birth control pills, so you should check with your doctor before starting selenium supplementation if you are currently taking any medication.

What are natural sources of selenium?

If you are interested in achieving your daily selenium intake through your diet, rich sources of selenium include:

Brazil nuts
Beef liver
Beef
Chicken
Turkey
Tuna
Sardines
Pork
Eggs
Bananas
Milk
Cheese
Yoghurt

Selenium data sources & further reading

Last updated by Asklepios on 30th January, 2025