30 Plants a Week: Does Dietary Diversity Really Improve Health?

One measure of this diversity is Dietary Species Richness (DSR), which counts the number of unique food species consumed over a given period. Different varieties of the same plant species do not necessarily increase this score. Other assessment methods take into account the proportions of different species and variations in the nutritional composition of foods.

Different plants contain varying combinations of vitamins, minerals, fibre and phytochemicals. Therefore, eating a diverse range of legumes, whole grains, vegetables, fruits, nuts, seeds, leafy greens and spices may help meet the body's nutritional requirements.

In a study involving 6,226 women and children from rural areas in seven low- and middle-income countries, greater dietary species diversity was associated with better nutritional status in terms of vitamins A and C, folate, calcium, iron and zinc. However, this observation does not prove that increasing dietary diversity alone can eliminate nutrient deficiencies.

A variety of plant-based foods may also influence the gut microbiome. Different types of fibre, polyphenols and resistant starch provide nourishment for gut microorganisms. During fibre fermentation, short-chain fatty acids, including butyrate, acetate and propionate, are produced. These compounds help maintain the intestinal barrier and regulate immune processes. Nevertheless, the direct effects of increasing the number of plant species in the diet on the human microbiome and the production of these compounds have not yet been sufficiently studied.

Some studies have also found associations between dietary diversity and the risk of chronic diseases. A European study found that every additional 10 food species included in the diet over the course of a year were associated with a lower risk of death from any cause and of developing gastrointestinal cancer.