Healthy diets may protect against dementia

Healthy diets may protect against dementia

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By Liji Thomas, MDMar 8 2019Reviewed by Kate Anderton, B.Sc.

The best way to keep your mind sharp as you age is to eat a healthy diet, according to recent research. The research suggests that following a varied dietary plan in middle-age can influence dementia risk in later life.

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One study looked at participants following a Mediterranean-style diet,  the Dietary Approaches to Stop Hypertension (DASH) diet, and A Priori Diet Quality Scores (APDQS) (a food quality score based on the nutritional benefits of particular foods).

The study included over 2600 participants, both male and female, aged 25 – 45 years. The diet of each participant was assessed by repeated questionnaires at three-time points, which were used to determine the average dietary intake for each individual.

Those who followed the first two diet patterns had the best cognitive health at 50 – 55 years, compared to the third. Why? These diets are heavy on monounsaturated fats, legumes, protein, fiber and micronutrients like thiamine, folate, magnesium, zinc, iron, and potassium.

The Western diet is rich in trans and saturated fats, highly processed vegetables and other foods, as well as refined sugar and salt. In contrast, the Mediterranean-style diet is rich in whole grains, nuts, fruits, vegetables, and olive oil and low in processed meat, red meat, trans or saturated fats, and refined sugars.

In addition to brain health, the Mediterranean diet has also been suggested to have protective effects against cardiovascular disease.

In another small study from St Louis University, participants eating a Mediterranean diet displayed better endurance-related performance compared to those following a conventional Western diet.

The participants ran five kilometers on a treadmill, once after four days on a Mediterranean diet, and another time after four days on a Western diet.

After this short four-day regime, the Mediterranean diet produced a 6% faster speed, despite heart rates being comparable during both runs.

The reason for this difference may be because a Mediterranean-type diet is more alkaline, has anti-inflammatory properties, contains nitrates, and is high in antioxidants.

This study provides evidence that a diet that is known to be good for health is also good for exercise performance. Now they have an additional incentive to eat healthy.”

Edward Weiss, Senior Researcher of the SLU study

It should be noted, however, that no significant benefits were observed for weight-bearing activities.

Weiss points out that multiple nutrients in the Mediterranean diet boost exercise performance on their own. This may account for the benefit resulting from their combination in a single dietary pattern. He warns, however: “Benefits were also quickly lost when switching to the Western diet, highlighting the importance of long-term adherence to the Mediterranean diet."

A third study exploring the way Australians ate showed that a brain-healthy diet was associated with the same reduction of risk for cognitive decline in their later life. This study used the Mediterranean-DASH Intervention for Neurodegenerative Delay diet, or the MIND diet, to assess the potential protection of a healthy diet against Alzheimer’s and other forms of dementia.

The MIND diet was developed by Professor Martha Morris, in the US. It borrows not only from the Mediterranean-type diet plan but also from a list of foods that are known to benefit brain health, like antioxidant-rich berries and green leafy vegetables.

MIND is thus distinguished from other similar-appearing plans by its detailed inclusion of brain-protective foods, apart from emphasizing whole grains, green leafy vegetables, olive oil and a very little red meat. Altogether, it contains 15 components.

The study looked at whether cognitive impairment developed over a span of 12 years in 1220 Australian adults of ages 60 years and over. At the beginning of the study, the scientists interviewed participants about their diet and analyzed the results using the CSIRO Healthy Diet Score, which measures the quality of eating habits.

In addition to traditional categories like green leafy vegetables and whole grains, CSIRO allows separate tracking of typical Western components such as cakes and pastries. This permits a simpler and more accurate picture of dietary pattern.

The answers were then assigned scores to group the participants into two groups: one followed the MIND and the other the Mediterranean diet.

The group who followed the MIND diet lowered their risk of developing cognitive decline or dementia by almost a fifth, compared to the average. The other group which was on the traditional Mediterranean diet showed zero benefit.

Kaarin Anstey, director of the UNSW Ageing Futures Institute, led the study in an attempt to reduce the incidence of dementia and make it possible to grow old without falling ill. In this context, she says, “This study has shown for the first time, outside of the United States, that the MIND diet reduces the risk of dementia.”

Source:

Dietary patterns in early life pay dividends for midlife cognitive performance. Neurology. 6th March 2019.