Studies show that ‘healthy’ dietary patterns rich in minimally processed foods, fresh fruits, vegetables, and lean proteins are linked to a lower risk of depression compared to ‘’unhealthy’ diets. Limited research until now, however, has explored the effects of dietary patterns beyond the ‘healthy’ versus ‘unhealthy’ dichotomy on depressive symptoms.
In the current study, researchers set out to assess how restrictive dietary patterns affect depression. To do so, they analyzed data from 28, 525 adults in the National Health and Nutrition Examination Survey 2007- 2018 who underwent dietary assessments and a survey for depression symptom severity.
Dietary patterns were categorized into four groups: caloric-restrictive, nutrient-restrictive such as being low in fat, sugar, or salt, established dietary patterns such as those for diabetes, and 'not on a diet'. The vast majority of participants- or 87%- did not follow any particular diet, whereas 8% followed a calorie-restrictive diet, 3% a nutrient-restrictive diet, and 2% an established dietary pattern. Altogether, 7.8% of adults reported depressive symptoms.
Ultimately, the researchers found that those following calorie-restrictive diets scored 0.29 points higher in depressive symptoms than those without any particular diet. Those who were overweight and followed a calorie restriction diet scored 0.46 points higher, whereas those on a nutrient-restrictive diet scored 0.61 points higher.
Scores also varied by sex. The researchers found, for example, that men following any diet displayed higher somatic symptom scores than those not on a diet. They further found that men on a nutrient-restrictive diet had a 0.4-point increase in cognitive-affective symptoms than women not following any diet.
“This study adds to the emerging evidence linking dietary patterns and mental health, raising important questions about whether restrictive diets which are low in nutrients considered beneficial for cognitive health, such as omega-3 fatty acids and vitamin B12, may precipitate depressive symptoms.” said Professor Sumantra Ray, Chief Scientist and Executive Director of the NNEdPro Global Institute for Food, Nutrition and Health, not involved in the study, in a press release.
“But the effect sizes are small, with further statistical limitations limiting the generalisability of the findings. Further well designed studies that accurately capture dietary intake and minimise the impact of chance and confounding are needed to continue this important line of inquiry,” he said.
Sources: EurekAlert, BMJ Nutrition Prevention & Health