Selenium, Brazil Nuts and Testosterone

Selenium is a mineral found in soil. It is also present in water and some foods – especially Brazil nuts. It plays a vital role in the metabolic process. However, we need only a tiny amount.

Selenium is known for its antioxidant properties. It is also believed to be a testosterone booster. Let us find out if there is enough scientific evidence to prove that selenium is effective at boosting testosterone levels.

Scientific Studies

Several studies have been conducted to understand the relationship between selenium and testosterone levels. Here is a summary of some of the critical studies.

Study: The relationship between serum levels of testosterone, zinc and selenium in infertile males attending fertility clinic in Nnewi, south-east Nigeria

This study was conducted to determine the serum levels of selenium, zinc and testosterone in infertile males attending a fertility clinic. The study involved 50 infertile men and 20 healthy fertile males between the ages of 25-50 years. Their serum zinc, selenium and testosterone levels were determined. Researchers found:

• A significant difference in serum zinc, selenium and testosterone levels between the two groups
• Strong positive correlation between serum levels of selenium and zinc
• A negative relationship between serum levels of zinc and testosterone
• A strong positive correlation between serum selenium and testosterone in infertile males

Study: Efficacy of Selenium and/or N-Acetyl-Cysteine for Improving Semen Parameters in Infertile Men: A Double-Blind, Placebo-Controlled, Randomized Study

The study involved 468 sterile males with idiopathic oligo-asthenoteratozoospermia. 116 participants received 200 μg selenium orally daily, 118 received 600 mg N-acetyl-cysteine orally daily, 116 men received 200 μg selenium plus 600 mg N-acetyl-cysteine orally daily, and 116 received placebo for 26 weeks. It was followed by a 30-week treatment-free period. At the end of study period, it was found:

• In the selenium and N-acetyl-cysteine treatment groups, serum follicle-stimulating hormone (FSH) decreased but serum testosterone increased
• Selenium and N-acetyl-cysteine treatment improved semen parameters
• Selenium and N-acetyl-cysteine combination resulted in added benefits

Study: Effect of zinc and selenium supplementation on serum testosterone and plasma lactate in cyclist after an exhaustive exercise bout

This study was conducted to understand how exercise affects testosterone levels and plasma lactate levels in cyclists who were given selenium and zinc supplements for four weeks.

The study involved 32 male cyclists, who were allocated to 4 groups: group 1 was supplemented with 200 μg/day selenium, group 2 received 30 mg/day zinc, group 3 received both zinc and selenium supplement and group 4 received placebo. After treatment, it was observed that:

• No significant difference in resting free, total testosterone, and lactate levels between groups, and were increased after exercise
• After exercise, testosterone levels were higher in zinc group compared to the selenium group

It was concluded that four weeks of separate and simultaneous selenium and zinc supplementation has no significant effect on resting testosterone levels of men who consume selenium and zinc-sufficient diet.

Selenium dosage and potential side effects

Recommended daily dosage is 55 mcg a day. The upper limit of selenium for adults is 400 mcg per day and even less for children. Selenium deficiency can cause various health problems. Some symptoms of deficiency include:

• Muscle pain and weakness
• Skin and hair discoloration
• Whitening of fingernail beds

Side Effects

Selenium side effects are rare and often a result of an overdose. Some potential side effects of selenium are:

• Nausea and vomiting
• Hair loss
• Skin Lesions
• Fatigue
• Irritability

Taking too much over a long period can cause serious side effects such as:
• Tremors
• Blood clots
• Muscle tenderness
• Liver problems
• Lightheadedness

How to take selenium?

Brazil nuts are known to be the most abundant source of selenium. A single brazil nut contains about 50 mcg of selenium. Other dietary sources of selenium include grass-fed beef, oysters, sardines and egg yolks.

There are various health supplements available in the market, which contain the right amount of selenium and possibly other minerals too.

Conclusion

Selenium can help increase testosterone levels and offer other reproductive health benefits, particularly in men who are deficient in this mineral. However, it may not affect testosterone levels in men who take sufficient selenium in their diet.

Also, a selenium overdose can cause some severe side effects, so one must follow dosage recommendations carefully.

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