Older people who like a variety of foods and flavours – from pepper and spices to eggs and meat – may have better brain health than those who prefer a more limited diet

According to a large study of British adults, older people who aren’t picky eaters appear to have better brain health than those who prefer more limited diets

The research, which tracked the dietary preferences of nearly 182,000 older adults in Britain, took a unique approach. Instead of focusing on the health effects of a particular diet, it examined the link between the foods individuals liked and disliked and their mental well-being and cognitive health

After parsing the data, the researchers noticed a trend: People who liked a variety of foods and flavours reported better mental health and well-being and did better on cognitive tests than those with limited dietary preferences

The findings suggest that a preference for a limited diet – such as a vegetarian diet or a high-protein diet –  may not always be best for overall well-being. Based on the results, people “need a more balanced diet to be better off,” says Jianfeng Feng, one of the study’s lead researchers, who works at both the Institute of Science and Technology for Brain-Inspired Intelligence at Fudan University in Shanghai and at the University of Warwick in Britain

Picky eaters vs. ‘balanced’ eaters

The research, published in the journal Nature Mental Health, was conducted by scientists from Britain and China. They looked at food preferences among participants in the U.K. Biobank study, one of the world’s largest and longest health research studies. The U.K. Biobank volunteers completed a “food-liking” questionnaire, ranking their preferences for 140 foods and beverages. The rankings were measured on a nine-point hedonic scale, in which 1 represents ‘extremely dislike’ and 9 represents ‘extremely like’

The ranked foods fell into 10 categories: alcohol, beverages, dairy, flavourings (such as black pepper, curry, ketchup, and vinegar), fruits, fish, meat, snacks, starches, and vegetables.

The researchers found that 57 percent of respondents showed a balanced preference across all 10 food categories, while others were pickier. One group (18 percent) preferred starch-free or reduced-starch foods, another 5 percent preferred a vegetarian diet, and the last group (19 percent) preferred eating more protein and less fibre

Some of the findings contradict conventional wisdom about healthy eating. For instance, individuals who preferred fruits and vegetables more than protein-rich foods –  suggesting a more vegetarian diet – “exhibited a heightened susceptibility” to symptoms of anxiety, depression and other forms of mental distress, says Wei Cheng, a professor at the Institute of Science and Technology for Brain-Inspired Intelligence at Fudan University. Other participants who favoured diets high in protein and low in fibre were also more likely to report symptoms of anxiety and “diminished well-being,” he says

It’s important to note that the data only correlate with certain food preferences and mental health. For instance, it may be that people who prefer certain food groups have other characteristics that could affect mental health scores

A link between food and brain health

The study adds to a growing body of research demonstrating how our food may affect our brain health. High-sugar, fatty diets –  also known as a ‘Western diet’ – have been associated with decreased cognitive performance. A small study of Finnish men found that a Western diet was associated with an increased prevalence of depressive symptoms. The Mediterranean Diet, high in fruits, vegetables, fish and olive oil, has been linked with a lower risk of Alzheimer’s disease

The study’s results “demonstrate that specific food preferences have significant associations with mental health, cognitive functions, blood and metabolic biomarkers and brain imaging,” says Rebecca MacPherson, an associate professor at Brock University in Ontario, Canada, who studies how exercise and diet can improve a person’s metabolism and brain health.  “There is a clear need for more preclinical studies investigating the underlying mechanisms,” as well as the short and long-term effects different nutrients can have “on the progression of disease”

The observational study has several limitations, the researchers say. Ruohan Zhang, a doctoral student at the University of Warwick and the lead author, says the data is based on preference for various foods, not what an individual actually consumes day-to-day. Participants in the U.K. Biobank are known to be comparatively healthier than the general population

The study described a ‘balanced’ diet as one that includes vegetables, fruits, cereals, nuts, seeds, pulses, moderate dairy, eggs and fish. That’s “just a very, very healthy diet,” says Thomas M. Holland, a physician-scientist at Rush University Medical Center in Chicago who was not involved in the research. “We know that diet impacts not only global cognition but many different domains, including semantic memory, episodic memory, working memory, perceptual speed”