Older women, in particular, may benefit from a more varied diet: A long-term Japanese study, published in the journal Clinical Nutrition in 2023 — that included 21,000 women ages 45 to 74 who were followed for an average of 11 years — found that women eating a more diverse diet had a lower risk of disabling dementia.
In many ways, eating a narrow range of foods is a global problem. While research is increasingly finding the health benefits of dietary diversity, humans are eating fewer and fewer kinds of food. According to data from the Food and Agriculture Organization of the United Nations, about 75 percent of the world’s food is now generated from only 12 plants and five animal species. And the average Western diet includes only a fraction of that.
Dr. Uma Naidoo, a nutritional psychiatrist and instructor at Harvard Medical School, has built a career around figuring out which foods may affect both our physical and mental health. Naidoo is the director of Nutritional and Lifestyle Psychiatry at Massachusetts General Hospital and author of This Is Your Brain on Food, as well as the upcoming Calm Your Mind with Food. To her, variety is not just the spice of life, it’s the key to a healthier life.
Eating a wide variety of foods “ensures you are getting a wide variety of vitamins, minerals and antioxidants to support both physical and mental health,” she said, explaining that, in particular, eating many different kinds of plant foods, like vegetables, fruits, whole grains and legumes, provides fiber and probiotics that feed the good bacteria in our gut. Naidoo adds that gut-healthy dining also boosts the mind, and “has been linked to reduced inflammation, particularly in the brain, which supports a good mood, reduced stress, healthy brain aging and optimal neurotransmitter function.”
Variety in your diet may also help you live longer. A study of 59,000 women, ages 40 to 76, who were followed for nearly 10 years, found that those whose diet regularly included a variety of 16 to 17 healthy foods — fruits, vegetables, whole grain breads and cereals, fish and low-fat dairy — had a 42 percent lower mortality compared to women who ate eight or fewer healthy foods. The study was published in 2002 in the International Journal of Epidemiology.
On her website, Naidoo offers her patients and others the following simple guidelines for adding more variety to their diet to help both their physical and mental health. As for me, I’ve taken the rainbow rule to heart. I’ve added more colorful sliced fruit and berries to my granola-and-yogurt breakfast, a variety of vibrant vegetables to my salad at lunch. For dinner, it’s no longer just broccoli but spicy roasted carrots, stir-fried Chinese cabbage and snow peas, or simply adding red, yellow and orange sauteed bell peppers to the sauce for my pasta. My motto now is: More colors, better health.
