The idea of consuming at least 30 different plant foods each week has gained popularity in wellness circles, with proponents suggesting it boosts gut health, reduces inflammation, and enhances overall well-being. However, experts say while dietary variety has recognized benefits, the specific “30 plants per week” target lacks strong scientific backing.

The concept encourages eating a broad range of plant-based foods—including fruits, vegetables, whole grains, legumes, nuts, seeds, herbs, and spices—and has inspired tracking apps and supplements marketed as containing 30 or more plant ingredients. Advocates claim this diversity supports a more varied gut microbiome, which is often associated with better health outcomes.

Research does indicate that gut microbiome diversity generally correlates with positive health markers. A 2018 study led by microbiome scientist Rob Knight from the University of California, San Diego, analyzed stool samples from 85 adults in the United States and Britain. Participants who reported eating 30 or more unique plants weekly had significantly more diverse gut microbiomes than those consuming 10 or fewer. This aligns with the theory that diverse dietary fiber selectively nourishes different microbes in the gut.

However, the study’s limitations include its small size and reliance on self-reported dietary data that may be imprecise. It also established correlation rather than causation. In a larger, as-yet unpublished analysis of more than 3,000 adults, Knight’s team found that eating between 11 and 20 unique plants weekly generated microbiome diversity comparable to eating 30 or more.

Additional trials explored the impact of the 30-plant goal more directly. A 2025 study involving 25 adults with chronic kidney disease in Australia reported improved bowel function and gut health markers among those consuming 30 or more plants weekly, compared to those eating 15 or fewer. Another trial published in July, involving approximately 400 adults, found that taking a supplement containing 30 different plants reduced constipation symptoms but did not increase microbiome diversity versus probiotic or placebo groups.

Nutrition experts caution that these results likely reflect increased fiber intake rather than plant variety alone. “It’s difficult to distinguish whether the benefits come from the additional fiber, the variety, or both,” noted Anissa Armet, a nutrition researcher at the University of Alberta. Claims that eating 30 plants weekly optimizes inflammation reduction, heart or immune health, energy levels, or longevity are not substantiated by current evidence.

Experts advocate focusing on meeting recommended daily fiber intakes—generally 21 to 38 grams depending on age and sex—through a diverse diet of whole plant foods. “Whole foods are better,” said Stanford Medicine’s Justin Sonnenburg, emphasizing that gut microbiomes are complex and individualized, with no universal target for diversity.

For some, setting a 30-plant weekly goal may encourage healthier eating patterns, but it could also be burdensome or anxiety-inducing for others, according to dietitian Lourdes Castro of New York University. Ultimately, increasing the variety of plant-based foods as part of a balanced diet remains a sound recommendation, even if the precise number 30 is not critical.