Preventing Allergies with Diet

Michael Greger (0:00)

We have lots of choices to make about our diet. Add to that doing the right thing when it comes to treating a chronic disease, fighting a virus, or losing weight, and suddenly our nutrition choices can seem almost overwhelming. Well, I'm here to help. Welcome to the Nutrition Facts Podcast. I'm your host, Dr. Michael Greger.

Diet may be one of the most powerful tools in the calming and overactive immune system. In our first story, we looked at the best diet for people who suffer from ragweed allergies. A great deal is asked of our immune system. On one hand, it has to respond rapidly and violently to invaders, but at the same time limits both the response and the collateral damage to the host. Anaphylactic shock, like when someone with a peanut allergy dropped dead after eating a peanut, is an example of an overactive immune response.

The flip side is an underactive immune response, which can put you at risk for infection. If you suffer some severe trauma, for example, it's not enough to get to a level 1 trauma center. Death related to sepsis, blood infection, still a major problem, and a major factor is the depression of our immune system caused by the stress of the trauma. So what these researchers did was to try to stimulate immune function in trauma victims by injecting them with beta-glucan, a type of fiber found in yeast, mostly car crash victims, but also gunshots and stab wounds. And not only did the beta-glucan group suffer less sepsis overall, they have five times fewer complications and no deaths compared to nearly one in three dying in the control group.

I've talked about the role of oral beta-glucans in the form of nutritional yeast to boost immune function in adults and children, but if it's so immunostimulatory, then might it increase inflammation, worsen allergies?

Actually, dietary yeast may offer the best of both worlds, possessing both anti-inflammatory as well as anti-microbial activities. On one hand, activating the immune system to prevent infections, on the other hand, capable of reducing inflammatory reactions. Given their best-of-both-worlds nature, enhancing immune defense while simultaneously down-regulating inflammation, beta-glucans are suggested as a replacement for immunosuppressant drugs to treat inflammatory diseases like inflammatory bowel disease.

Turns out that's a bad idea for Crohn's disease, since it can make things worse. The same with another disease called the hydradenitis suppurativa, but what about allergies like hay fever?

They did a nasal provocation test with tree pollen and then siphoned off some mucus, and those that had been taking beta-glucans had lower levels of some inflammatory compounds, or should I say inflammatory compounds.

And based on just that, they suggest it might help people with hay fever, but you don't know until you put it to the test. A randomized placebo-controlled double-blind study compared the effects of daily supplementation per month, with about a teaspoon of nutritional yeast worth of beta-glucans versus placebo on the physical and psychological health of self-described moderate ragweed allergy sufferers. The ragweed family is one of the leading causes of hay fever, and give people a placebo, and nothing much happens. But in the beta-glucan group, a significant drop in symptoms and symptom severity. Fewer runny noses, fewer itchy eyes, and fewer sleep problems. So, no wonder less tension, depression, anger, fatigue and confusion, and more vigor. So improved allergy symptoms, overall physical health, and emotional well-being with the beta-glucans found in a single teaspoon of nutritional yeast, which would cost about five cents a day.

In our next story, we look at the rising incidence of tick-bite-induced meat allergies. Tick-bite-induced meat allergies are really unlike any other food allergy we know. The most interesting feature of the reaction may be the first symptom can occur hours after eating meat. Normally you have an allergic reaction to a bee sting or something, and it happens within minutes. But with this, you could eat a piece of bacon for breakfast, and your throat doesn't start closing off until the afternoon, and so you blame lunch, or doctors just call it spontaneous, or idiopathic anaphylaxis. Idiopathic is just doctor speak for we have no idea what the cause is. The delay is because the alpha-gal is thought to be absorbed along with the fat in the meat, given that the allergic reaction occurs four to five hours after meat ingestion, corresponding to the peak absorption time of the fat from the digestive tract. What makes it even more difficult to diagnose is that the majority of victims experience only occasional overt reactions despite regular meat consumption. Fattier meats like pork rinds may provoke episodes more consistently and severely, but still it's not like it happens every time. And it's on the rise. Ten years ago, we didn't even know the thing existed, but now in tick-ridden states, as many as 20% of the population have these anti-meat allergic antibodies, and more and more people are coming in affected. Though probably no more than 10% who test positive go on to experience hives or serious allergic reactions to meat.