Nutrition science has a tendency to identify a single compound or food and promote it until the research catches up with more nuanced findings. Resveratrol, lycopene, acai, kale, and numerous other foods and compounds have had their moment as the most important nutritional discovery of the decade, only for the research to reveal that the benefits observed were part of a broader dietary pattern effect rather than a single food effect. The pattern always matters more than the individual food.
The Microbiome Argument for Variety
Different species of gut bacteria require different fibre types and polyphenols for their growth and maintenance. Bacteroides species prefer the specific polysaccharides in certain vegetables. Bifidobacterium species prefer the inulin found in chicory, Jerusalem artichokes, garlic, and onions. Akkermansia muciniphila is stimulated by polyphenols from cranberries and pomegranate. No single food can support all beneficial bacterial species. Dietary variety is the only way to maintain full microbiome diversity, and microbiome diversity is a primary marker of gut and systemic health.
The Practical Implication
Eating the same seven to ten foods every week, even if those foods are nutritionally excellent, will produce a less diverse microbiome and a narrower nutritional profile than rotating through 25 to 30 different whole foods. The simplest upgrade to any healthy diet is not to find a better version of what you already eat, but to add foods you are not currently eating. New vegetables, different legume varieties, unfamiliar grains, and diverse protein sources all contribute to variety in ways that buying a more expensive version of a familiar food does not.