Transcript: Treating Asthma With Plants vs. Supplements?
This landmark study on manipulating antioxidant intake in asthma found that just a few extra servings of fruits and vegetables a day can powerfully reduce asthma exacerbation rates. If it's the antioxidants doing it, why can't you just take antioxidant pills instead?
Because they don't seem to work. Studies using antioxidant supplements on respiratory or allergic diseases have mostly shown no beneficial effects. This discrepancy between studies relating to fruit and vegetable intake compared with those using antioxidant supplements may indicate the importance of the whole food, rather than individual components.
For example, in the Harvard Nurse's Health Study, women who got the most vitamin E from their diet appeared to be at half the risk for asthma, which may help explain why nut consumption is associated with significantly lower rates of wheezing, but vitamin E supplements did not appear to help.
Men who eat a lot of apples appear to have superior lung function. Same with kids who eat fresh fruit every day, as measured by FEV1, which is basically how much air you can forcibly blow out in one second. The more fruit, salad, and green vegetables kids ate, the greater their lung function appeared. Why are there no data points for more than once daily consumption of salad and veggies? Because so few kids made the cut.
They were cautious about concluding which nutrient might be responsible. Yes, there's vitamin C in all three, but there's lots of other antioxidants, for example so called vitamin P, polyphenol phytonutrients found in grapes, flax seeds, beans, berries, broccoli, apples, citrus, herbs, tea, and soy. Turns out they can directly bind to allergenic proteins and render them hypoallergenic to slip them under our body's radar. And if their first line of defense failed, they can inhibit the activation of the allergic response and prevent the ensuing inflammation, and so may not only work for prevention, but for treatment as well.
Most of the available evidence is weak, though, in terms of using supplements containing isolated phytonutrients to treat allergic diseases. You could just give people fruits and vegetables to eat, but then you can't do a double-blind study to see if they work better than placebo. So researchers decided to try to use pills containing plant-food extracts. It's kind of a middle ground. Better than isolated plant chemicals, but not as complete as whole foods. Still, you can put it in a capsule, so you can compare them to sugar pill placebo capsules that look and feel the same to see if there's anything to them.
The first trial involved giving people extracts of apple skins. I've talked about the big problem they have in Japan with cedar allergies, so apple extract pills were given every day for a few months starting right before pollen season started. The results were pretty disappointing, maybe a little less sneezing, but didn't seem to help their stuffed noses or itchy eyes.
What about a tomato extract? A randomized, double-blind, placebo-controlled eight-week trial for perennial allergic rhinitis. This time not for seasonal pollen, but for year-round allergies to things like dust-mites. There's lots of drugs out there, but you may have to take them every day year-round, so how about some tomato pills instead? A significant improvement of total nasal symptom scores, combined sneezing, runny nose and nasal obstruction were all observed after oral administration of tomato extract for eight weeks with no apparent adverse effects.
Would whole tomatoes work even better? If only researchers would design an experiment directly comparing phytonutrient supplements to actual fruits and vegetables head to head against asthma, but such a study had never been done, until now.
The same amazing study that compared the seven fruit and vegetables a day diet to the three fruit and vegetables a day diet then commenced a parallel, randomized, controlled supplementation trial with capsules of tomato extract, which boosted the power of five tomatoes in one little pill, and the study subjects were given three pills a day.
So who did better, the group that ate seven servings of actual fruits and vegetables a day, or the group that ate three servings a day but also took 15 supposed serving equivalents in pill form? The pills didn't help at all. Improvements in lung function and asthma control were evident only after increased fruit and vegetable intake, which suggests that whole-food interventions are most effective. Both the supplements and increased fruit and vegetable intake were effective methods for increasing carotenoid concentrations in the bloodstream, but who cares. The clinical improvements, the getting better from disease, was evident only as a result of an increase in plant consumption, not pills. The results provide further evidence that whole-food approaches should be used to achieve maximum efficacy of antioxidant interventions.
And if this what a few more plants can do, what might a whole diet composed of plants accomplish? I'll cover that next.
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 Ariel Levitsky.
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