Dr. Greger just posted, rather reposted (from 5 years ago) this video about Brazil nuts reducing cholesterol. It’s something else.

Transcript:

This is one of the craziest articles I saw all year. A single consumption of high amounts of Brazil nuts improves the cholesterol levels of healthy volunteers. OK, that’s interesting. They gave 10 men and women a single meal containing zero, one, four, or 8 Brazil nuts, and found that the ingestion of just that single serving almost immediately improved cholesterol levels. LDL, so-called “bad” cholesterol levels in the blood were significantly lower starting just nine hours after the ingestion of nuts, and by no insignificant amount, nearly 20 points within a day. Even drugs don’t work that fast. It takes statins like four days to have a significant effect. But that’s not even the crazy part. They went back and measured their cholesterol five days later, and then 30 days later. Now keep in mind they weren’t eating Brazil nuts this whole time. They had just that single serving of Brazil nuts a month before and their cholesterol was still down 30 days later. It went down and stayed down, after eating just four nuts… That’s nuts!

And no, the study was not funded by the Brazil nut industry.

Interestingly, four nuts actually seemed to work faster than the 8 nuts to lower bad cholesterol and boost good cholesterol. These results suggest that eating just four nuts might be enough to improve the levels of LDL-c and HDL-c for up to 30 days, and maybe longer—they didn’t even test past 30.

Now normally, when a study comes out in the medical literature showing some too-good-to-be-true result like this you want to wait to see the results replicated before you change your clinical practice, before you recommend something to your patients, particularly when the study is done on only 10 people, and especially when the findings are literally just too incredible to be believed. But when the intervention is cheap, easy, harmless, and healthy—eating four Brazil nuts a month—then in my opinion, the burden of proof is kind of reversed. I think the reasonable default position is to do it until proven otherwise, so now every month I eat four Brazil nuts. In conclusion, a single serving is sufficient, without producing liver and kidney toxicity. I should hope not, but what they’re referring to is the high selenium content of Brazil nuts, so high that four eaten every day may actually bump us up against the tolerable daily limit for selenium, but not something we have to worry about it we’re just eating four once a month.

Not funded by industry. A nearly 20-point cholesterol reduction within a day. The effect lasted for 30 days (they didn’t test longer) without additional nuts. Wow. You have to wonder what else the nuts are doing besides reducing cholesterol, because nothing with this strong an effect does just one thing.

Brazil nuts are very high in selenium. Here’s an old chart I made back in 2004:

The RDA for selenium is about 55 micrograms. The tolerable upper limit (UL) is about 400 micrograms. So these four nuts that Dr. Greger advises do, as he says, bump up againt the UL.

Here are signs you’re bumping up against the upper limit:

Early indicators of excess intake are a garlic odor in the breath and a metallic taste in the mouth. The most common clinical signs of chronically high selenium intakes, or selenosis, are hair and nail loss or brittleness. Other symptoms include lesions of the skin and nervous system, nausea, diarrhea, skin rashes, mottled teeth, fatigue, irritability, and nervous system abnormalities. … Acute selenium toxicity can cause severe gastrointestinal and neurological symptoms, acute respiratory distress syndrome, myocardial infarction, hair loss, muscle tenderness, tremors, lightheadedness, facial flushing, kidney failure, cardiac failure, and, in rare cases, death.

The NIH says, “Brazil nuts contain very high amounts of selenium (68–91 mcg per nut) and could cause selenium toxicity if consumed regularly.”

However, besides the study of 10 people Dr. Greger mentioned, there was this larger study (more people, longer time) which found a similar cholesterol-lowering effect from selenium, although this effect was a lot smaller:

Effect of Supplementation With High-Selenium Yeast on Plasma Lipids: A Randomized Trial, Annals of Internal Medicine, May 2011

From NIH:

In one randomized, placebo-controlled study, 474 healthy adults aged 60 to 74 years with a mean baseline plasma selenium concentration of 9.12 mcg/dL were supplemented with 100, 200, or 300 mcg selenium per day or placebo for 6 months. The supplements lowered levels of total plasma cholesterol and non–high-density-lipoprotein (HDL) plasma cholesterol (total cholesterol levels minus HDL levels) compared with the placebo group, whereas the 300 mcg/day dose significantly increased HDL levels.

The amounts:
100 mcg selenium reduced total cholesterol by 8.5 mg/dL
200 mcg selenium reduced total cholesterol by 9.7 mg/dL
300 mcg selenium reduced total cholesterol by 2.7 mg/dL

From the study:

Conclusion: Selenium supplementation seemed to have modestly beneficial effects on plasma lipid levels in this sample of persons with relatively low selenium status. The clinical significance of the findings is unclear and should not be used to justify the use of selenium supplementation as additional or alternative therapy for dyslipidemia. This is particularly true for persons with higher selenium status, given the limitations of the trial and the potential additional risk in other metabolic dimensions.

Did you see that downward dip at the higher 300 mcg dose? Hm. This study says that high blood levels of selenium have also been linked to high cholesterol.

You have to be careful with this. It looks like a little selenium is good but more isn’t.

My take? If you want to lower your cholesterol, change your diet. Don’t depend on a magic pill, or nut. Choose a low-fat, plant-based diet. I guarantee your cholesterol will go down and you won’t risk selenium toxicity.