Zel's Vegan NutGourmet

Zel Allen Goes Nuts for Good Health


Posted by Zel Allen's nutgourmet on April 30, 2010

For many years I’ve known that consuming one Brazil nut a day supplies the human body with its daily requirement for selenium, an important trace mineral high in antioxidants. But here’s what I recently learned that gave me a bit of a jolt. Recent studies show that while Brazil nuts have many positive attributes, they also have a hidden side that sparked researchers to express cautionary advice.

I turn to nature rather than food manufacturers to provide the most nourishing foods for human consumption. I’m also cognizant that we humans absorb our vitamins and minerals best from pure, natural foods rather than from synthetically manufactured supplements. Human nature is kind of funny, though. We often have a tendency to believe that if a small amount of a nutrient-dense food or supplement is good for us, wouldn’t gobbling down double, triple, or five times the amount be even better?

That theory works well for some foods, like dark leafy greens, but it doesn’t apply across the board. That mind-set is especially problematic when it comes to Brazil nuts.

The good news
On the positive side, Brazil nuts, like all nuts, are highly nutritious and densely packed with minerals like calcium, copper, iron, magnesium, manganese, potassium, and zinc. Brazil nuts also possess trace amounts of thiamine, riboflavin, and niacin in the B vitamin family, along with healthy levels of folate and vitamin E. Clearly, these nuts are remarkably nutritious.

Brazil nuts stand apart from all other nuts with their exceptionally high levels of selenium. The Recommended Daily Allowance (RDA) for selenium for adults 19 years and up is 55 micrograms a day. According to the USDA National Nutrient Database for Standard Reference, one Brazil nut delivers 95.8 micrograms of selenium, well over the daily requirement for the mineral.

In comparison, other nuts do not even come close to measuring up. Pine nuts contain the least selenium, registering only 0.2 micrograms for one ounce, while cashews weigh in with 5.6 micrograms per ounce, the highest quantity after Brazil nuts.

A randomized controlled study conducted at the University of Otago in New Zealand found that consuming two Brazil nuts daily is as effective in boosting selenium levels in the blood as taking selenomethionine, a synthetic selenium supplement. The group that ate two Brazil nuts a day also measured higher in antioxidant levels than those taking the supplement. Selenium, required only in small amounts, helps the body to produce antioxidant enzymes that protect the cells from free radical damage. Study authors also found that those with adequate levels of selenium in the blood have a reduced risk for breast and prostate cancer.

A double-blind, placebo-controlled study, known as the Nutritional Prevention of Cancer trial noted that in populations where selenium consumption was low, there was a rise in the incidence of cancer. The long-term trial involving 1312 individuals found supplementation with selenium reduced the total cancer incidence by 48% to 63%, especially prostate, colorectal, and lung cancer. Generally, the dietary selenium levels in the U.S. population are considered good. The trial was conducted where dietary levels were poor. Considering the results of the study conducted at the University of Otago, two Brazil nuts a day may have been equally as effective in this population as the selenium supplement.

Selenium is found in the soil where plant foods can absorb it through their root systems. Other plant-based foods high in natural selenium include most nuts, whole grains like corn, wheat, oats, and rice, along with foods of the legume family, including soybeans.

An exceptional plus for Brazil nuts is their high level of the antioxidant glutathione peroxidase (GPx), that may bestow benefits on our health in multiple ways:

• Boosting the immune system
• Protecting from cardiovascular disease
• Improving fertility
• Helping ward off the growth of cancerous cells
• Increasing thyroid metabolism

Not only does our immune function work best when selenium levels are adequate, but the mineral is an important component that prevents deficiencies that could impair thyroid function.

The bad news
In spite of their many positive qualities, Brazil nuts might be considered the bad boys of the nut family. Because Brazil nuts have an exceptionally high concentration of phytic acid, measuring 2% to 6% in their hulls, they might interfere with the absorption of some nutrients like iron, zinc, calcium, and magnesium. While their monounsaturated and polyunsaturated fats may be beneficial in lowering cholesterol when ingested in small quantities, Brazil nuts high level of saturated fat (25%) could possibly raise cholesterol levels if the nuts are consumed in large quantities.

Overdosing on selenium can cause a toxic condition known as selenosis, leaving patients with a host of nasty symptoms like hair loss, nausea, vomiting, abdominal pain, sloughing of the fingernails, fatigue, irritability, and nerve damage. Less common are cirrhosis of the liver and kidney failure.

While a 12-week study of 60 volunteers published in the American Journal of Clinical Nutrition, February 2008, found that study participants consuming two Brazil nuts a day had higher levels of selenium compared with those consuming a 100-microgram supplement or taking a placebo, the research concluded with a cautionary message.

Professor Christine Thomson, Department of Human Nutrition University of Otago, says, “People should be careful to limit themselves to no more than a few Brazil nuts per day, otherwise selenium could potentially accumulate to toxic levels in body tissues. Also, as the nuts can contain relatively high amounts of the elements barium and thorium, people should avoid eating too many as it is still unclear what intake of these elements might be harmful.”

Another study, prompted by the UK National Diet and Nutrition Survey, was conducted because of concern that the average selenium consumption in the UK is far below the recommended levels of 75 micrograms per day for men and 60 micrograms for women.

Several studies have shown an association of high levels of selenium in the blood and increased risk of type 2 diabetes, high cholesterol, and risk of heart disease. Researchers at the Warwick Medical School in Coventry, England, conducted an observational study involving 1,042 individuals, aged 19 to 64, to measure how selenium levels in the blood compared to their blood cholesterol status. In this UK National Diet and Nutrition Survey conducted 2000 to 2001, participants’ blood selenium was measured, and they were asked specific lifestyle questions about diet and alcohol consumption.

The findings revealed that participants with 1.20 micromols (about 94 micrograms) of selenium in the blood showed an average 8 percent rise in total cholesterol and a 10 percent rise in LDL cholesterol, the bad cholesterol associated with heart disease. Study authors noted that while these results raise concerns, they were unable to show positively that increased selenium levels in the blood were the cause of the jump in cholesterol levels or whether it was due to other factors. Those individuals who tested in the upper levels of selenium in the blood revealed they were regularly taking selenium supplements.

Lead author Dr. Saverio Stranges says, “The cholesterol increases we have identified may have important implications for public health. In fact, such a difference could translate into a large number of premature deaths from coronary heart disease.” Dr. Stranges expressed further concern, “We believe that the widespread use of selenium supplements, or of any other strategy that artificially increases selenium status above the level required, is unwarranted at the present time. Further research is needed to examine the full range of health effects of increased selenium, whether beneficial or detrimental.”

Study authors also examined the levels of the antioxidant glutathione peroxidase and found that those with the higher levels of selenium in their blood had an 8 to 10 percent increase in total cholesterol.

When published studies revealed that selenium may be able to fight off cancer, the news sparked interest in the mineral and created a demand for the supplements. However, there still remains no definitive evidence that the antioxidants in selenium can prevent such diseases.

While a handful-a-day of most nuts is beneficial in raising antioxidant levels and effective in lowering total and LDL cholesterol levels, the handful-a-day mantra is off the table for Brazil nuts. Stick with the recommended quantity of one or two Brazil nuts per day. A whole handful of the nuts could easily boost one’s blood selenium to unhealthy levels.

As much as I love nuts and consider them a healthy food source for my everyday diet, I have adopted the safe mantra that nut researchers conclude in study after study: A LITTLE BIT GOES A LONG WAY. In the case of Brazil nuts, eat one or two nuts a day, then, STOP.

“Brazil Nuts Health Benefits.” Suite101.com.

“Eating Just Two Brazil Nuts a Day Ensures Adequate Selenium Levels.” Health Freedom Alliance.

Jackson, Malcolm J., Caroline S. Broome, and Francis McArdle. “Marginal Dietary Selenium Intakes in the UK: are There Functional Consequences?” The American Society for Nutritional Sciences. Supplement: 11th International Symposium on Trace Elements in Man and Animals. The Journal of Nutrition, 133:1557S-1559S, May 2003

“Selenium.” Wikipedia, the Free Encyclopedia

Stranges, Saverio, Martin Laclaustra, Chen Ji, Francesco P. Cappuccio, Ana Navas-Acien, Jose M. Ordovas, Margaret Rayman, and Eliseo Guallar. “Higher Selenium Status is Associated with Adverse Blood Lipid Profile in British Adults.” Journal of Nutrition. doi:10.3945/jn.109.111252, November 11, 2009.

Thompson Christine .D., Alexandra Chisholm, Sarah K. McLachlan, and Jennifer M. Campbell. “Brazil nuts: an effective way to improve selenium status.” American Journal of Clinical Nutrition, Vol. 87, No 2, 379-384, February 2008

USDA National Nutrient Database for Standard Reference


  1. hekowelve said

    Just want to say what a great blog you got here!
    I’ve been around for quite a lot of time, but finally decided to show my appreciation of your work!

    Thumbs up, and keep it going!

    Christian, iwspo.net

    • nutgourmet said

      Christian, Thanks a million for the great support. Feels good. And thanks for taking the time to express your appreciation. I appreciate that. Please do pass the word on the blog. I’m anxious to have more people discover the many benefits of nuts.


  2. anardana said

    Thank you for the scientific testing info! Great post.

    • nutgourmet said

      Hi Ardana, Thanks so much for the kind words. Checked out your website and found myself salivating over the asparagus ideas and your homemade rye bread.

  3. justin said

    Good stuff, I knew a little about brazil nuts but this helps out. That was really in depth, I think as long as you don’t go overboard and consume too much brazil nuts would be benificial.

    • nutgourmet said

      Hi Justin, Thanks for the positive feedback on the Brazil nut article. I felt the information was so important, it needed to be shared. The best way to live with Brazil nuts healthfully, is to limit yourself to 1 or 2 Brazil nuts a day, while other nuts can bring health benefits by consuming a handful or two a day.

  4. Audrey said

    Thank you for sharing this information! I found it really interesting and helpful. It sounds like if I eat one brazil nut every other day I should be okay, right? I’m assuming that would fill in the selenium gap not covered by other grains, nuts, and legumes but still not be too much that it would be dangerous. Such a fine balance in the nutrition world!

    • nutgourmet said

      Hi Audrey,

      I think it’s safe to enjoy a couple of Brazil nuts a day without causing health problems. You could even occasionally eat a handful without concern. The major issue is when people overdose on Brazil nuts on a daily basis. Over time, that can possibly become a health issue. Brazil nuts are awesome! Enjoy them in moderation.


  5. Excellent write-up on brasil nuts!! 🙂 Thank you for this precious piece of information.
    The Jaminet couple>/a> speaks highly of suplementation with brasil nuts because of the selenium, but I wasn’t aware of the need for a limit. So thanks for that.
    Meanwhile, you might eventually want to review your position on saturated fat and the outdated belief that cholesterol is linked to heart disease; not only it is not true (there are no valid scientific studies that prove it), it is also a red herring the size of the moon.
    all 5 parts of the lecture, you won’t regret it. And this is merely the tip of the iceberg, if you follow the references and names he gives there, you will discover an entire new universe of reality.
    Obviously, I’m on a Paleo/Primal lifestyle and haven’t found one single bad thing to say about it.

    • nutgourmet said

      Hi Vasco, So glad you found the brazil nut article informative. I really enjoy the research process and love to discover the many health studies that show the benefits of including nuts in the diet on a regular basis. Of course, not too many nuts at one time. Please do visit often.

  6. Sorry, forgot to close the link tag on that last comment… oops. 🙂

  7. Pam Doughty said

    Thank you so much for the great information on the Brazil nut. I am not one to stop at one so this is going to help me out a lot.

    • Zel Allen's nutgourmet said

      Hi Pam, So glad my Brazil nut post was helpful to you. Do visit often for lots of other nutty postings. Zel

  8. Jason Scott said

    Great blog, thanks for all the wealth of nut info!

    Any idea how long on average from harvest until a Brazil nut (in shell) goes bad? I was wondering in cases of ‘stocking up’ in bulk

    Thanks again!

    • Zel Allen's nutgourmet said

      Hi Jason, Thanks for the kind words on my nutgourmet blog. Once harvested, nuts have impressive longevity, but that longevity depends on how they are stored. In the shell, they can keep at room temperature for 6 to 9 months. You can stretch their lives by refrigerating them. Once shelled, most nuts keep at room temperature for about one month. If you refrigerate shelled nuts, you’ll be able to keep them fresh for about 6 to 8 months. Freezing nuts in the shell or out of the shell will allow you to keep them for up to 1 year. You may be able to stretch that a few months, but you’ll find variations, depending on when they were harvested. Hope this helps. Zel

  9. Nina said

    Hello Zel,
    Thank you soooooooo much for all the data, I have just found this link! Brilliant and very helpful ! I have just discovered the benefits of Brazilian nuts and had my first two (: Will keep on reading and discovering !!! :::::Thanks you again:::::

  10. wow, this is one of the best- researched, most informative blogs I have ever seen. Thanks for the wonderful information!

    • Zel Allen's nutgourmet said

      Hi Dr. Siegel, Thanks so much for those very kind words. They’re so appreciated. Hope you’ll return for more visits. I’m the author of The Nut Gourmet, a cookbook that features nuts in a host of delicious plant-based recipes. My new cookbook, Vegan for the Holidays will be coming out this summer. Zel

  11. Laura said

    Hi Doc,
    For the last three years I would eat 10-15 a day with a day or two in between. I do have hair falling out and nails splitting etc.. If I did overdose on selenium, can the damage be permanent on the organs?
    Is there a test I can do?
    Thank very much for this info!!!!

    • Zel Allen's nutgourmet said

      Hi Laura, So sorry to hear about your health challenges. I’m not a medical practitioner, but my suggestion is to consult one. You may have overdosed, but I don’t have the expertise to say for sure. Meanwhile, discontinue eating Brazil nuts and do not take any selenium supplements. As for what else you can do, consider consulting a registered dietitian. I’ll send my best wishes for quick healing. Zel

      • Nodyah said

        He stated the Brazil nuts have an exceptionally high concentration of phytic acid, measuring 2% to 6% in their hulls. Phytic acid is hard on the pancreas over time and could lead to problems as well as interfering with the absorption of some nutrients like iron, zinc, calcium, and magnesium. .The hull would include the dark skin around the Brazil nut, but not the white meat of the nut. It seems if you peel off the dark brown skin, you would not have so much of an issue with phytic acid and solve a few problems.

      • Zel Allen's nutgourmet said

        Hello Nodyah, Thanks so much for your interest in my blog article on Brazil nuts. It has always been my instinct that when nuts are consumed in moderation, they are healthful. Unless one has a nut allergy, consuming 1 Brazil nut a day ought to keep one safe from the problems caused by consuming an excess. That 1 Brazil nut contains more than the daily requirement of selenium, so there is no need for more than one Brazil nut a day. Phytic acid in small doses is usually not a problem for most people, but it’s easy to remove the hulls to avoid it completely. I also recognize that variety is important to prevent unpleasant reactions from eating only a single variety of nut day after day that may lead to allergic reactions. – Zel

  12. Lyn Flores said

    I love Brazil nuts, and since December I have been eating 6 to 8 nuts almost every day.
    . My cholesterol has always been very low, until my blood test this week when it was so high my Dr. thought about putting me on a low level of medication. He asked me what had changed in my diet and the only thing that had was my consumption of Brazil nuts. Now after reading this article, I know why my cholesterol has gone so high. Thanks for the information. I will immediately cut down on the nuts. In 2 months I will have another blood test and I bet my count will be normal again. Who Knew? ( I will also make sure the hull is removed.) LYN

    • Zel Allen's nutgourmet said

      Hi Lyn,

      I’m so glad to hear my Brazil nut article was helpful to you. Nuts of all varieties are a bit sneaky. They make you fall in love with them instantly, making it tempting to overeat them. Brazil nuts, with their very buttery flavor, are especially enchanting. But they are troublesome as well. Usually, studies show that 1 ounce of nuts per day helps to lower cholesterol, but Brazil nuts are higher in saturated fat (about 22%) than, say almonds, pecans, and walnuts (8%).For now, you may want to kick it back to 1 or 2 a week, until your cholesterol comes down. Usually 1 Brazil nut a day is all anyone would need. That single Brazil nut actually provides more than the daily requirement for selenium. Here’s to a normal cholesterol reading on your next test.


  13. jane lisle said

    Thanks so much for the info. I’ve been eating 3-5 brazil nuts a day for approx 6 mths now. And, as it happens, for approx 6 mths now i’ve been losing “distressing” amounts of hair and my fingernails have been terribly weak and pealing, “a lot” 😦 So i’ll change my brazil nut eating habits posthaste and see if my hair and fingernails return to a healthy state. Thanks again 🙂

    • Zel Allen's nutgourmet said

      Hi Jane,

      So sorry to hear about your distressing Brazil nut experience. Nuts, a very healthful category of food, would seem like benign, friendly foods, but not so Brazil nuts. Because of their very high content of selenium, they ought to be eaten sparingly. Even 1 Brazil nut contains much more than the daily requirement for selenium and too much selenium can cause a host of health problems. For now, I would suggest you stop consuming Brazil nuts alto