Mediterranean diet may help lower depression risk in older women

The Italian NutBrain study involved 325 men and 473 women who were aged 65–97, with a mean age of 73.

Each participant responded to a 102-item questionnaire regarding their daily diet, allowing researchers to calculate each person’s Mediterranean diet score (MDS). Individuals were divided into three groups, or tertiles, based on how closely they followed the diet.

Participants were also assessed for depression using the Center for Epidemiological Studies Depression Scale.

Overall, 19.8% of the study’s participants reported symptoms of depression — 27.9% of women compared with 8.0% of men.

People who scored within the top third of MDS scores were 55% less likely to experience depressive symptoms. Women in this tertile were around 60% less likely to report symptoms of depression.

Digging deeper into dietary elements, the researchers observed an association between eating more fish and monounsaturated fatty acids, compared with unsaturated fatty acids, and a greater reduction in depression.

While eating more fish was linked to a 44% overall reduction in depression risk for those in the top third of the tertiles, the reduction for women was 56%. For each gram of fish consumed per day, the risk fell by 2% for women.

When three or more servings of fresh fish were consumed weekly, the risk of depression was reduced by 62%; there was no association with canned tuna.

Monounsaturated fatty acids found in foods such as olive oil, peanuts, avocados, almonds, pecans, hazelnuts, and cashews are an important component of the Mediterranean diet.

The researchers observed that women who consumed a greater proportion of monounsaturated fatty acids versus saturated fatty acids had a 42% lower risk of depressive symptoms.

Nut and fruit consumption reduced the risk of depressive symptoms by 82% for men.

Michelle Routhenstein, registered dietician and nutritionist at EntirelyNourished.com, not involved in this study, told Medical News Today that:

“The observation that the protective effects of the Mediterranean diet components primarily affect women is surprising, given the potential biological mechanisms, such as vitamin D deficiency and alterations in brain-cell membrane composition, which are typically not gender-specific.”

At the same time, Routhenstein noted that its is important to remember that depressive symptoms were much more prevalent in women than in men. Then, she added, “women with depressive symptoms were more likely to be unmarried, live alone, take more medication, and to have poorer perceived health status.”

By contrast, registered dietician nutritionist Kristin Kirkpatrick, also not involved in this research, told us she was not surprised by the greater benefit to women of the Mediterranean diet, given the results of other existing research.

She reported that “[a] 2021 study found that non-nutrient rich diets had a greater adverse impact on women’s mental health than men, and a 2018 study found that men and women had differences in dietary patterns and mental well-being.”

As for why this disparity may exist, Kirkpatrick cited some research that suggests there could be “differences in the brain, or perhaps it also relates to the data showing that women are more susceptible to mental illness than men and that women react differently to various stressors than men as well.”

Routhenstein listed some health benefits of eating fish and consuming monounsaturated fatty acids that may explain their effects on depressive symptoms in women:

“Fish, rich in omega-3 fatty acids, and monounsaturated fatty acids found in the Mediterranean diet possess anti-inflammatory properties and support brain health. They potentially reduce the risk of depression through neurotransmitter modulation and neuroprotection,” said Routhenstein.

“Multiple trials,” said Kirkpatrick, “including the HELFIMED and SMILES trials, found that [diets that included] the addition of fish oil led to reductions in depression scores.”

Routhenstein added that “the cardiovascular benefits associated with these nutrients may indirectly contribute to improved mental well-being.”

“Other components of the [Mediterranean] diet such as whole grains, fruits and vegetables, extra virgin olive oil, nuts, and seeds have all been associated with better mental health outcomes,” said Kirkpatrick.

Routhenstein explained that “[p]olyphenols, flavonoids, and phytochemicals found abundantly in Mediterranean diet staples like fruits, vegetables, nuts, seeds, and olive oil possess antioxidant and anti-inflammatory properties which may help reduce oxidative stress and inflammation in the body.”

“These bioactive compounds,” Routhenstein said, “have been associated with improved mood, cognitive function, and reduced risk of depression by supporting optimal brain health and neurotransmitter function.”

“Additionally, the limitation of sugar and refined grains in the diet can also play a role of better mental health,” pointed out Kirkpatrick.

“All of these components may also impact the microbiome, which in turn, we are learning has a large impact on mental health outcomes as well,” Kirkpatrick noted.