Transcript: Nutritional Yeast to Prevent the Common Cold
Natural immunomodulators, something that can help regulate our immune system without side effects, have been sought for centuries, and all the while they’ve been sitting in the produce aisle. Plants produce thousands of active compounds, many of which modulate our immune system enough to protect us from infection, but we can’t forget the fungi. Mushrooms have used for centuries as folk remedies, and for good reason—some have been shown to boost immune function as well. So much so, a type of fiber found in shiitake mushrooms is approved for use as adjunct chemotherapy, injected intravenously to help treat a variety of cancers by rallying our immune defenses.
More than 6,000 papers have been published on these so-called beta glucans, but almost all the data about preventing infections had come from petri dish or lab animal studies, until a few years ago when a series of experiments on athletes showed beneficial effects–but that was in marathon runners. What about the rest of us? We didn’t know, until now.
Beta glucan fiber, found in baker’s, brewer’s and nutritional yeast, helps to maintain our body’s defense against pathogens even in non-athletes according to this double-blind, randomized, placebo-controlled trial. Reducing the recurrence of infections with the common cold by 25% in those who ate the equivalent of about a spoonful of nutritional yeast a day, and had fewer cold-related sleeping difficulties if they did get sick.
What about half a spoonful a day’s worth? Still worked! Big drop in common cold incidence and a reduction in symptoms as well. Why though? This study found that not only were upper respiratory infection symptoms diminished, but that mood states appeared to improve like a significant boost in feelings of “vigor.” So they suggest that maybe the yeast fiber is able to counteract the negative effects of stress on the immune system.
In terms of side effects, two folks reported stomachaches, but they were both in the placebo group.
Unlike antibiotics and antivirals, which are designed to kill the pathogen directly, these yeast compounds instead appear to work by stimulating our immune defenses, and as such don’t share the same antibiotic side effects. They stimulate our immune defenses presumably because our body recognizes them as foreign. But if it’s treated like an invader, might it trigger an inflammatory response? Turns out it may actually have an anti-inflammatory effect, suggesting nutritional yeast may offer the best of both worlds, boosting the infection-fighting side of the immune system while suppressing the inflammatory component. So oral intake can be considered safe and effective. Note they said oral intake, though. I would not recommend injecting nutritional yeast into your veins, no matter how much you like the stuff.
Yeast is high in purines, so those with gout, uric acid kidney stones, and new organ transplant recipients may want to keep their intake to less than a teaspoon a day, but for everyone else, is there any downside? Well if you look at some packages of nutritional yeast, in California some are slapped with Prop 65 warning stickers suggesting there’s something in it exceeding cancer or birth defect safety limits. I called around to the companies and it turns out the problem is lead.
California state law says a product cannot contain more than half of a microgram of lead per daily serving, so I contacted the six brands I knew about and asked them how much lead was in their products. KAL originally said “<5 ppm,” but when we called back they said “<3 ppm.” But even if it’s 3 ppm, that translates into less than 45 micrograms per serving, nearly 100 times more than the California limit. But perhaps better than Bob’s Red Mill or Frontier Coop, who evidently didn't test at all. But at least they got back to me. Red Star brand failed to respond to multiple attempts to contact them. Now Foods said of course we test for lead–that’s nice–and claim that at least their recent batches meet the less than half a microgram California standard. Unfortunately, despite repeated requests, they would not provide me with documentation to substantiate their numbers.
My favorite response was from Bragg’s, who sent me the analysis certificate from the lab showing less than 0.01 ppm, which means at most less than half the California standard, which I believe is the most stringent in the world. To put the numbers in context, in determining how much lead manufacturers can put into candy likely to be frequently consumed by small children, the Food and Drug Administration would allow 2 micrograms a day in the form of lollipops, but as far as I’m concerned, the less lead the better.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
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