A new study published in the online journal Neurology found that consuming a diet comprised primarily of fruits, vegetables, fatty fish and nuts is associated with better cognition in middle age.
Individuals who eat a MedDiet have been shown to accumulate less beta-amyloid, a protein associated with Alzheimer's disease and dementia, compared to those eating a typical Western Diet.
“Our findings indicate that maintaining good dietary practices throughout adulthood can help to preserve brain health at midlife” said study author Claire T McEvoy of Queen’s University Belfast in Northern Ireland.
Participants consisted of 2,621 adults with an average age of 25 at the study’s onset. They provided information about their diet at the beginning of the investigation, as well as seven and 20 years later. Their cognition was tested twice: once at age 50 and again at age 55.
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For each diet, the participants were assigned to low-, medium- or high-adherence groups, depending on how closely their food intake resembled three heart-healthy eating plans. These included the Mediterranean diet (MedDiet), the Dietary Approaches to Stop Hypertension (DASH) diet, and the A Priori Diet Quality Score [APDQS] diet:
- MedDiet foods involve fruits, vegetables, whole grains, legumes, nuts, fatty fish and olive oil. Red meat and poultry are limited.
- The DASH diet consists of fruits, vegetables, grains, legumes, low fat dairy and nuts. It limits meat, poultry, fish, total fat, saturated fat, sodium and sweets.
- APDQS foods include fruits, vegetables, low-fat dairy, fish, legumes and moderate alcohol. Salty snacks, sweets, high-fat dairy products, fried food and sugar-sweetened beverages are limited.
Results showed an association with preservation of cognition with the MedDiet and the APDQS diet. Participants with high adherence to the MedDiet had a 46-percent lower likelihood of poor thinking skills than those with low adherence.
Those with high adherence to the APDQS diet showed a 52-percent decreased risk of poor thinking skills compared to those with low adherence. Large differences were seen in fruit and vegetable consumption between the high- and low-adherence groups. The findings were adjusted for factors that can influence cognition such as smoking, level of education and physical activity.
It was not clear why the DASH diet was not tied to a cognitive advantage, but McEvoy speculated one factor might be alcohol.
“One possibility is that DASH does not consider moderate alcohol intake as part of the dietary pattern, whereas the other two diets do,” McEvoy said. “It’s possible that moderate alcohol consumption as part of a healthy diet could be important for brain health in middle age, but further research is needed to confirm these findings.”
Additional studies are needed to identify exact combinations of foods and nutrients that promote optimal cognitive health throughout life. In the meantime, McEvoy recommends following the MedDiet or APDQS diet to protect against mental decline.
“While we don’t yet know the ideal dietary pattern for brain health, changing to a heart-healthy diet could be a relatively easy and effective way to reduce the risk for developing problems with thinking and memory as we age,” she said.
Brian Bender, a certified nutritionist, biomedical engineer and a cofounder of Intake, told Olive Oil Times how heart-healthy diets, such as the MedDiet, may protect against mental decline.
“Individuals who eat a MedDiet have been shown to accumulate less beta-amyloid, a protein associated with Alzheimer’s disease and dementia, compared to those eating a typical Western Diet,” he said. “One theory for how a MedDiet may do this relates to a protein called ApoE, which typically binds to beta-amyloid and shuttles it out of the brain.”
“However, individuals who eat a Western Diet produce less ApoE compared to those on a MedDiet,” he added. “Thus, the high intake of fruits, vegetables and legumes, along with healthy fat from olive oil, nuts and oily fish appear to help the brain ward off beta-amyloid buildup that is associated with cognitive decline.”