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20 Years of Research Reveals A Famous Diet Doesn't Do Much To Reduce Dementia Risk : ScienceAlert

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According to a 20-year study done in Sweden, the “Mediterranean diet” does not lower the chances of developing dementia.

Previous studies on the potential cognitive benefits of the Mediterranean diet, generally defined as a diet rich in unsaturated fats such as vegetables, legumes, fruits, fish and olive oil, and low in dairy products, red meat, and saturated fats – reports to the National Institutes of Health’s National Institute on Aging (NIA) ) revealed mixed results.

However, two 2019 studies featured in the journal JAMA Decades of follow-up involving thousands of people found no evidence that the Mediterranean diet reduces dementia risk or that diet quality affects dementia risk overall.

The new Swedish study casts more doubt on the diet’s brain-boosting benefits.

A member of the Clinical Memory Research unit at Lund University in Sweden, first author Dr. “We did not find any association between traditional dietary habits or adherence to a Mediterranean diet and the incidence of dementia,” Isabelle Glans told Live Science. an e-mail.

These findings, which are in line with those found in previous studies of similar size and length, were published Oct. neurology.

However, similar to many previous studies, the research relied on participants’ self-reported dietary data, which may not be entirely accurate and may somewhat distort the interpretation of the results.

Related: Brain ‘pacemaker’ for Alzheimer’s shows promise in slowing decline

The effect of diet on dementia

Physiologist Ancel Keys and husband-and-wife biochemist Margaret Keys derived the Mediterranean diet from Ancel’s influential research on the link between men’s diets and their risk of heart attack and stroke.

Research has suggested that diets low in saturated fat protect against cardiovascular disease, and Ancel and Margaret drew loose inspiration from Greek, Italian, and other Mediterranean cuisines to write their popular diet books, according to The Conversation.

In theory, the Mediterranean diet may indirectly reduce the risk of dementia by protecting against cardiovascular disease, according to the NIA.

This is because plaque buildup in the arteries (atherosclerosis), stroke, high blood pressure, high blood sugar, and diabetes can increase the risk of dementia, and maintaining a healthy diet can help reduce the risk of these conditions.

Swedish research does not completely reverse this idea, but suggests that diet alone does not have a significant impact on the course of cognitive function in later life.

Dr. “Diet as a singular factor may not have a strong enough effect on cognition, but rather is considered an embedded factor with various others, the sum of which can influence the course of cognitive function,” says Dr. Benedetta Nacmias, a neurologist at the Hirslanden Stroke Center in Zurich, Switzerland, and an associate professor of neurology at the University of Florence, wrote in a comment published Oct. neurology.

These other factors include exercising regularly; avoiding smoking; drink only in moderation; and keeping someone’s blood pressure under control, they wrote. In particular, the evidence suggests that regular physical activity and consistent blood pressure control are protective against cognitive decline, and that these factors are likely more effective than diet, according to the NIA.

The new research included data from nearly 28,000 people who participated in the Malmö Diet and Cancer Study, a study started in Malmö, Sweden in the 1990s.

At the start of the study, the participants were, on average, 58 years old; then they provided dietary data in the form of a weekly food diary; a detailed questionnaire about the frequency and amount of consumption of various foods; and an interview about eating habits.

Based on this information, the research team “scored” each participant according to how strictly they adhered to standard Swedish dietary recommendations or a particular version of the Mediterranean diet.

Related: A large Mediterranean diet study has been pulled back. But do doctors still recommend it?

Over the next 20 years, 1,943 people, or 6.9 percent of respondents, were diagnosed with some form of dementia. These diagnoses included the two most common forms of dementia: dementia due to Alzheimer’s disease (AD) and vascular dementia caused by poor blood flow to the brain.

The researchers found that participants who adhered to a traditional diet or Mediterranean diet did not have a lower incidence of either type of dementia than participants who did not fit well. They also found no link between diet and a specific marker of Alzheimer’s disease, which they screened in about 740 of the participants with cognitive decline.

Overall, Peters and Nacmias wrote that the study “does not show any particular effect of diet on the course of cognitive function.” But they noted that, like similar studies done in the past, the study had limitations.

For example, the basic nutritional information gathered from each participant may not reflect how their diets have changed over time. What’s more, study participants may have somehow misreported their actual eating habits.

The best way to test the long-term effect of the Mediterranean diet on cognition would be to conduct a long-term randomized controlled trial. In such a trial, groups of participants would be asked to follow specific diet plans, even given whole foods over an extended period of time, and monitored thoroughly for signs of dementia.

“However, it is probably not feasible to design a 20-year randomized controlled trial with strict dietary habits,” the study authors wrote in their report.

Some such short-term trials can be found on the NIA website and on the Alzheimers.gov Clinical Trials Finder. But for now, the available evidence suggests that the Mediterranean diet is not a silver bullet for dementia prevention.

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This article was originally published by Live Science. Read the original article here.

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