Treating Asthma With Plants vs. Supplements?

In my video Treating Asthma With Fruits and Vegetables, I highlighted a landmark study on manipulating antioxidant intake in asthma. The study found that just a few extra fruits and vegetables a day can powerfully reduce asthma exacerbation rates. If the antioxidants in the plants are ameliorating asthma, then why can’t we take antioxidant pills instead? Because antioxidant pills don’t work.

Studies using antioxidant supplements on respiratory or allergic diseases have mostly shown no beneficial effects. This discrepancy between data 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, as do kids who eat fresh fruit every day, as measured by FEV1 (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.

Researchers are “cautious about concluding which nutrient might be responsible.” There’s vitamin C in fruits, salads, and green vegetables, but there are lots of other antioxidants, such as “vitamin P,” a term used to describe polyphenol phytonutrients found in grapes, flax seeds, beans, berries, broccoli, apples, citrus, herbs, tea, and soy. Polyphenol phytonutrients can directly bind to allergenic proteins and render them hypoallergenic, allowing them to slip under our body’s radar. If this first line of defense fails, polyphenols can also 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. We could just give people fruits and vegetables to eat, but then we couldn’t perform a double-blind study to see if they work better than placebo. Some researchers decided to use pills containing plant food extracts. Plant extracts are kind of a middle ground. They are better than isolated plant chemicals, but are not as complete as whole foods. Still, since we can put it in a capsule, we can compare them to fake sugar pills that look and feel the same to see if they have an effect.

The first trial involved giving people extracts of apple skins. I’ve talked about the Japan’s big cedar allergy problem before (See Alkylphenol Endocrine Disruptors and Allergies), so apple extract pills were given every day for a few months starting right before pollen season started. The results were pretty disappointing. They found maybe a little less sneezing, but the extract didn’t seem to help their stuffy noses or itchy eyes.

What about a tomato extract? A randomized, double-blind, placebo-controlled eight-week trial was performed on perennial allergic rhinitis, this time not for seasonal pollen, but for year-round allergies to things like dust-mites. There are lots of drugs out there, but you may have to take them every day year-round, so how about some tomato pills instead? After oral administration of tomato extract for eight weeks, there was a significant improvement of total nasal symptom scores, combined sneezing, runny nose and nasal obstruction, 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, after completion of its first phase, 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.

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? Clinical improvements—getting better from disease—were evident only as a result of an increase in plant, not pill, consumption. The results provide further evidence that whole-food approaches should be used to achieve maximum efficacy of antioxidant interventions.

And if this is what a few more plants can do, what might a whole diet composed of plants accomplish? See Treating Asthma and Eczema with Plant-Based Diets.

Here’s my video about the fruit and vegetable treatment study: Treating Asthma With Fruits and Vegetables. I also dealt with preventing asthma in the first place: Preventing Asthma With Fruits and Vegetables.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of DeathMore Than an Apple a Day, and From Table to Able.

Minimum “Recommended Daily Allowance” of Antioxidants
Dietary Sources of Alkylphenol Endocrine Disruptors
Antioxidant Rich Foods With Every Meal


Paulo R
Paulo Reeson2 months ago


Paulo R
Paulo Reeson2 months ago


Pamela W
Pamela Wabout a year ago

I have had ASTHMA my whole life but about 7 years ago my asthma got so bad and was diagnosed of EMPHYSEMA/COPD which was most likely due to the asthma. I was on double antibiotics and steroids, still didn't feel any better. My lungs were constantly wheezing in all four chambers, i already used Advair, Spiriva, and Albuterol in my nebulizer, they just didn’t do much. April 2016 my sister in-law told us about Rich Herbs Foundation where she ordered herbs that effectively treated her arthritis. We ordered their COPD herbal treatment after reading alot of positive reviews, i am happy to report this COPD herbal treatment reversed my lungs condition. My quality of life has greatly improved and every one of my symptoms including difficulty breathing and wheezing are gone. Their official web page is ww w. richherbsfoundation. c om. I will be 52 soon and have never been healthier!

Clare O
Clare O'Bearaabout a year ago

Do not take full fat milk if you have asthma. Semi skimmed is okay.

Roxana S
Roxana Saezabout a year ago


Jeanne Rogers
Jeanne Rogers3 years ago

Thank you for sharing.

Nina S.
Nina S3 years ago


Sherry Kohn
Sherry Kohn3 years ago

Many thanks to you !

heather g.
heather g4 years ago

I'm a vegetarian but still read anything likely to help me cope with nightly asthma - mine results from poor air quality and dust.

Carol P.
Carol P4 years ago

Sigh. Though I get that the way this study is written up, Greger doesn't have to spin to fit his agenda, but until you look at what foods the fruits and vegetables were replacing, you really can't know if it was the fruits and vegetables that had a positive impact, or if the removal of foods that had a negative impact didn't make more of a difference.

For instance, eating less bread would help reduce asthma symptoms in someone who has gluten intolerance and eating less processed food would reduce symptoms in someone who reacts to additives. And there are plenty more food intolerances out there.

So the claim this study makes isn't all that reliable because it presumed that the outcome was based on an additive process and completely overlooked that it is just as likely, if not more, that it was a subtractive process that made a difference.