Q: I’ve heard that I should eat at least 30 unique plant foods a week for my health. Is that true?
When Kathryn Smith, 26, a surgical athletic trainer in Atlanta, first heard on a podcast that eating 30 different plants every week could improve her health, she liked the idea of having a tangible goal.
She began making homemade granola with oats, nuts and seeds; salsas with chili peppers, cucumber, avocado and herbs; and bean salads with corn, tomatoes and mango.
The idea of eating 30 (or more) plants each week — including fruits, vegetables, whole grains, legumes, nuts, seeds, herbs and spices — has taken the wellness world by storm. It has spawned apps that track how many plants you eat and supplements advertising 30 or more plants per capsule or scoop. Thousands of social media posts have mentioned the practice, with many touting benefits like lower inflammation, better heart health, more energy, a stronger immune system and a longer life.
Eating 30 plants a week, some influencers, podcasters and physicians say, will diversify your gut microbiome and in turn, improve your health. Does the evidence match the buzz? We asked experts to help us break it down.
What the Research Suggests
Eating 30 different plants per week is a catchy notion, said Justin Sonnenburg, a professor of microbiology and immunology at Stanford Medicine. But while consuming plenty of vegetables, whole grains and other plants is good for your health, there isn’t strong evidence that the 30-plant target is a “magical threshold,” he said.
Its origin traces back to an analysis from 2018, in which researchers compared stool samples from 85 adults living in the United States and Britain. About half of the adults said they typically ate 10 or fewer unique plants per week; the rest said they ate 30 or more. Those in the latter group had significantly more diverse gut microbiomes, said Rob Knight, a microbiome scientist at the University of California, San Diego, who led the study.
It makes sense that eating a variety of plants could encourage microbiome diversity, Dr. Knight said. Gut microbes are primarily nourished by fiber, so in theory, eating different types of fiber promotes the growth of different kinds of microbes. Researchers have found that less diverse gut microbiomes are generally associated with poorer health.
The study had limitations, however, said Anissa Armet, a nutrition researcher at the University of Alberta in Canada. It was small and relied on participants’ estimations of how many plants they typically ate each week, which could have been inaccurate, she said. And it showed only an association between eating more plants and microbiome diversity; it didn’t prove causation.
When Dr. Knight and his colleagues did a larger analysis using data from more than 3,000 adults, they found that eating 11 to 20 plants per week was associated with similar microbiome diversity as eating 30 or more. Meaning, it wasn’t necessary to eat 30 plants to see the benefits, Dr. Knight said. That analysis, however, has not been peer-reviewed or published.
A few limited studies have since tested variations on the 30-plant target, Dr. Armet said. In a 2025 trial involving 25 adults with chronic kidney disease in Australia, researchers found that consuming 30 or more plants per week (compared with 15 or fewer) led to less constipation and more favorable markers of gut health. And in a trial involving about 400 adults published in July, researchers found that those who took a “30-plant” supplement for six weeks reported less constipation, but had no increase in microbiome diversity, relative to study participants who took a probiotic supplement or a placebo made from bread croutons. (The study was funded by ZOE, the company that sells the supplement.)
Because the participants in both studies increased their fiber consumption in pursuit of the 30-plant goal, the researchers couldn’t say whether the increase in the variety of plants, the extra fiber or a combination of the two was responsible for the benefits, Dr. Armet said.
And contrary to some online claims, she added, there’s no evidence that 30 plants per week is an optimal amount to reduce inflammation, improve heart or immune health, increase energy or prolong life-span.
That said, research generally supports the benefits of eating a variety of plant foods; it just doesn’t back the 30-plant target, Dr. Sonnenburg said. People’s microbiomes are complex and unique; there’s no one-size-fits-all advice, he added.
The Bottom Line
If you enjoy the challenge of eating 30 plants a week, go for it, said Lourdes Castro, a dietitian and adjunct professor of nutrition at New York University. It may help you eat more fiber and more diverse foods, which can benefit your health, she said.
But some people might feel overwhelmed by tracking their meals or anxious about meeting the target, Ms. Castro said.
A more evidence-based goal, Dr. Armet said, would be to consume the recommended amount of fiber — 21 to 38 grams per day, depending on your age and sex — from a variety of plant foods.
And skip the supplements, Dr. Sonnenburg said. “Whole foods are better.”