One of the craziest studies I read all year involved feeding people a single serving of brazil nuts to see what it would do to the cholesterol levels of healthy volunteers. They gave ten men and women a single meal containing zero, one, four, or eight 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, was 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 around four days to have a significant effect.
But that’s not even the crazy part.
The researchers 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 just had 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 eight 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 and HDL for up to 30 days, and maybe longer—they didn’t 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 ten 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.
They concluded a single serving was sufficient “without producing liver and kidney toxicity.” 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 if we’re just eating four once a month.
Michael Greger, M.D.