(Healthline) – Testosterone is the main male sex hormone. It plays a key role in male development, and low levels can affect sexual function, mood, energy levels, hair growth, bone health, and more (1Trusted Source, 2Trusted Source).
Levels of this hormone naturally decline with age, with studies suggesting that hypogonadism, a condition in which the body doesn’t produce enough testosterone, affects 39% of men aged 45 and over in the United States (3Trusted Source).
Though hormone replacement therapy (HRT) is the most common way to treat low testosterone levels, many men seek natural supplements or foods that can boost their testosterone levels.
Recently, Brazil nuts have become more popular among men, as they are said to help raise testosterone levels and aid fertility.
This article explores the effects of Brazil nuts on testosterone.
What the science says
Brazil nuts are said to boost testosterone levels due to their high selenium content.
A 1-ounce (28-gram) serving provides a whopping 988% of the Daily Value (DV) (4).
Several studies have shown that taking a selenium supplement may improve testosterone levels or aid male fertility by enhancing semen quality (5Trusted Source, 6Trusted Source, 7Trusted Source).
For example, a test-tube study in sheep cells found that supplementing with selenium activated genes and pathways that enhanced testosterone production (8Trusted Source).
Similarly, a 26-week study in 468 men with infertility noted that taking 200 mcg of selenium along with 600 mg of N-acetyl-cysteine daily increased testosterone production, sperm count, and sperm quality, compared with a placebo (9Trusted Source).
Another study in 690 men with infertility observed that taking 200 mcg of selenium along with 400 units of vitamin E for 100 days improved sperm motility and appearance in 53% of participants. Plus, 11% of men in the study were able to get their partners pregnant (10Trusted Source).
However, in some studies, a high intake of selenium through foods or supplements had either no effect on testosterone levels or negatively affected sperm motility (11Trusted Source, 12Trusted Source).
Also, it’s worth noting that most of these studies use selenium supplements rather than foods high in selenium, such as Brazil nuts.
This highlights the need for more research on Brazil nuts’ effects on testosterone levels specifically.
Some studies show that high selenium intake may improve testosterone levels, sperm motility, and sperm quality. Still, more studies are needed to confirm this effect.
Other benefits of Brazil nuts
Aside from raising testosterone levels and aiding male fertility, Brazil nuts have been linked to many other impressive health benefits, including:
Good source of antioxidants. Brazil nuts boast antioxidants, such as selenium, vitamin E, and phenols like ellagic acid. Selenium can also raise levels of glutathione peroxidase, an enzyme that has antioxidant properties and fights oxidative stress (13Trusted Source, 14Trusted Source, 15Trusted Source).
Help support thyroid function. Brazil nuts are high in selenium, which helps support the production of thyroid hormones. This nutrient is also essential for making proteins that protect your thyroid gland from damage (16Trusted Source, 17Trusted Source).
Good for your heart. They’re high in heart-healthy fats, such as polyunsaturated fats, and have been linked to lower levels of LDL (bad) cholesterol and higher levels of HDL (good) cholesterol (18Trusted Source, 19Trusted Source).
May aid brain function. Certain antioxidants in Brazil nuts, such as ellagic acid and selenium, have been linked to protective effects on the brain. Also, ellagic acid may have mood-elevating properties (20Trusted Source, 21Trusted Source, 22Trusted Source).
May lower blood sugar levels. Some studies have found that diets higher in Brazil nuts or supplemented with selenium may reduce blood sugar levels and improve insulin sensitivity (23Trusted Source, 24Trusted Source).
May reduce inflammation. Diets higher in Brazil nuts and selenium have been linked to reduced markers of inflammation due to their antioxidant properties (25Trusted Source, 26Trusted Source).
While these findings are promising, more human studies are needed before recommendations can be made regarding Brazil nuts’ potential to help treat these conditions.
Brazil nuts are a good source of antioxidants, may have anti-inflammatory effects, and have been linked to benefits for the thyroid gland, heart, brain, and blood sugar levels.
Dangers of eating too many Brazil nuts
Though Brazil nuts offer health benefits, eating too many can be harmful.
Research has shown that eating more than 5,000 mcg of selenium per day, or approximately 50 Brazil nuts, can cause selenium toxicity (27Trusted Source).
Signs of selenium toxicity include gastrointestinal issues, hair loss, brittle nails, fatigue, skin lesions or rashes, and muscle and joint pain. In severe cases, selenium toxicity may cause kidney failure, heart failure, acute respiratory distress syndrome, and even death (28).
However, reaching toxicity levels through diet alone is quite rare.
Other studies have found that too much selenium, especially from supplements, is linked to poor blood sugar control, as well as a higher risk of diabetes and prostate cancer (29Trusted Source, 30Trusted Source, 31Trusted Source).
Selenium has a tolerable upper intake level of 400 mcg per day, which means you can safely consume up to this amount without adverse effects. That is equal to 4 average-sized Brazil nuts per day (27Trusted Source).
Try to limit yourself to one to three Brazil nuts per day to be safe.
Eating too many Brazil nuts can be harmful due to their high selenium content. Try to limit your Brazil nut intake to one to three per day.
Natural ways to increase testosterone levels
Though Brazil nuts may help raise testosterone levels, more research is needed before it can be recommended for this purpose.
Fortunately, other strategies to boost your testosterone levels are supported by more research, including:
Exercise. Exercise, especially weight lifting and high-intensity interval training (HIIT), has been linked to higher testosterone levels among older men (32Trusted Source, 33Trusted Source, 34Trusted Source).
Get plenty of sleep. A lack of sleep has been linked to lower testosterone levels in young and older men. Aim for 7–9 hours of sleep per night (35Trusted Source).
Aim to reduce stress. Long-term stress may raise cortisol levels, which is linked to lower testosterone levels. Regular exercise, sleep, laughter, and a healthy diet can all help reduce stress (36Trusted Source, 37Trusted Source).
Lose excess fat. Research suggests that obesity is linked to lower testosterone levels, and losing weight can help combat this (38Trusted Source).
Eat a healthy, varied diet. A balanced diet that incorporates healthy proteins, fats, fruits, and vegetables and limits refined foods may help boost testosterone levels (39Trusted Source, 40Trusted Source, 41Trusted Source).
In some cases, low testosterone could be due to an underlying medical condition, so it’s important to speak with your healthcare provider if you think you have low testosterone.
Common symptoms that occur with low testosterone include fatigue, low sex drive, erectile dysfunction, depression, hair loss, and muscle loss (3Trusted Source).
Regular exercise, sufficient sleep, minimizing stress, losing excess fat, and eating a healthy, varied diet may help raise testosterone levels. If you suspect that you have low testosterone levels, seek advice from your healthcare provider.