Recent research has shed light on the profound impact of diet quality and diversity on the human gut microbiome, surpassing the influence of mere dietary types. Led by researchers from Università di Trento, the study emphasizes that the nutritional quality and variety in a diet play a critical role in shaping the gut microbiome's structure, regardless of following a vegan, vegetarian, or omnivorous diet. This study, published in Nature Microbiology, highlights how a balanced and diverse intake of foods can contribute significantly to overall gut health.
The research findings underscore that many Americans fall short of consuming the recommended daily servings of fruits, vegetables, and whole grains, instead overindulging in animal products, dairy, and ultra-processed foods. This dietary imbalance poses risks to gut health and can lead to a reduced diversity of beneficial microbes. The study also revealed that vegetarians and vegans exhibited lower species diversity compared to omnivores. In contrast, omnivores showed higher concentrations of bacteria associated with meat digestion, as well as microbes linked to inflammatory bowel disease (IBD) and an increased risk of colon cancer.
Nicola Segata, PhD, noted the association between certain microbes and health conditions, emphasizing that while these microbes could indicate an increased risk for diseases such as colorectal cancer, they are not definitive markers. He stated:
“It’s important to underline that individuals with increased amounts of those microbes do not generally have IBD and colorectal cancer, but according to other studies those microbes might be a sign of an increased risk for developing those conditions. It is well-known that red meat is a risk factor for colorectal cancer, for example, and the microbes we found higher in individuals eating more red meat could be part of the reason, even though our work did not focus directly on the effects of the microbes on health.” — Nicola Segata, PhD
The study also highlighted the importance of consuming a variety of plant-based foods. Nicola Segata explained that greater diversity in plant-based foods leads to a more diverse array of beneficial gut microbes:
“The greater the variety of plant-based foods we consume, the greater the diversity of beneficial microbes in our gut. This is because different plant-based foods contain different types of fiber, and each fiber can stimulate the growth of different types of health-promoting microbes. These microbes work together to improve our gut health, so the more diversity of health-associated microbes in our gut microbiome, the better our chances of good gut health.” — Nicola Segata, PhD
The Brassicas family — including brussels sprouts, cauliflower, kale, collards, and cabbage — was specifically recognized for its numerous benefits related to gut and immune health. In contrast, iceberg lettuce was noted for its relatively low nutrient content.
Bedford commented on the significance of food variety within groups:
“Food groups such as vegetables are important but also the variety within those food groups are key. For example, the Brassicas (Brassicaceae) family (brussel sprouts, cauliflower, kale, collards, cabbage) have numerous benefits related to gut and immune health, whereas a small amount of iceberg lettuce shreds will not have the same level of beneficial nutrients and interaction in the gut.” — Bedford
Monique Richard, MS, RDN, LDN, offered a practical dietary guideline by recommending a balanced division of one's plate:
“A visual recommendation is to think about our plate in four equal quadrants. One being for lean protein (fish, poultry, beans, etc.), one for whole grains or a starch (oats, quinoa, potato), one for vegetables (cabbage, broccoli, carrots), and one for fruit (berries, pineapple, apples). If each of these quadrants is represented by different foods within the food groups per meal and possibly enhanced with the added benefits of spices or herbs our nutritional needs will be met and gut bacteria may be doing a happy dance.” — Monique Richard, MS, RDN, LDN
Segata also highlighted the complexity and individuality of each person's microbiome:
“However, each person’s microbiome is very ‘personal’ — two individuals may share over 99.9% of their human genome, but they usually share less than 5% of the genetics of their microbiomes — and also each person’s diet is both complex and unique.” — Nicola Segata, PhD
The study was funded by ZOE Limited, a personalized nutrition program company. These findings emphasize that while diet type is significant, it is ultimately the quality and diversity within that diet that determine gut microbiome health.
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