Which foods do you eat together? How you combine them may raise dementia risk

Study finds 'food networks' centered on processed meats, starches may raise risk

April 22, 2020

Science Daily/American Academy of Neurology

t's no secret that a healthy diet may benefit the brain. However, it may not only be what foods you eat, but what foods you eat together that may be associated with your risk of dementia, according to a new study published in the April 22, 2020, online issue of Neurology®, the medical journal of the American Academy of Neurology. The study looked at "food networks" and found that people whose diets consisted mostly of highly processed meats, starchy foods like potatoes, and snacks like cookies and cakes, were more likely to have dementia years later compared to people who ate a wider variety of healthy foods.

"There is a complex inter-connectedness of foods in a person's diet, and it is important to understand how these different connections, or food networks, may affect the brain because diet could be a promising way to prevent dementia," said study author Cécilia Samieri, PhD, of the University of Bordeaux in France. "A number of studies have shown that eating a healthier diet, for example a diet rich in green leafy vegetables, berries, nuts, whole grains and fish, may lower a person's risk of dementia. Many of those studies focused on quantity and frequency of foods. Our study went one step further to look at food networks and found important differences in the ways in which food items were co-consumed in people who went on to develop dementia and those who did not."

The study involved 209 people with an average age of 78 who had dementia and 418 people, matched for age, sex and educational level, who did not have dementia.

Participants had completed a food questionnaire five years previously describing what types of food they ate over the year, and how frequently, from less than once a month to more than four times a day. They also had medical checkups every two to three years. Researchers used the data from the food questionnaire to compare what foods were often eaten together by the patients with and without dementia.

Researchers found while there were few differences in the amount of individual foods that people ate, overall food groups or networks differed substantially between people who had dementia and those who did not have dementia.

"Processed meats were a 'hub' in the food networks of people with dementia," said Samieri. "People who developed dementia were more likely to combine highly processed meats such as sausages, cured meats and patés with starchy foods like potatoes, alcohol, and snacks like cookies and cakes. This may suggest that frequency with which processed meat is combined with other unhealthy foods, rather than average quantity, may be important for dementia risk. For example, people with dementia were more likely, when they ate processed meat, to accompany it with potatoes and people without dementia were more likely to accompany meat with more diverse foods, including fruit and vegetables and seafood."

Overall, people who did not have dementia were more likely to have a lot of diversity in their diet, demonstrated by many small food networks that usually included healthier foods, such as fruit and vegetables, seafood, poultry or meats.

"We found that more diversity in diet, and greater inclusion of a variety of healthy foods, is related to less dementia," said Samieri. "In fact, we found differences in food networks that could be seen years before people with dementia were diagnosed. Our findings suggest that studying diet by looking at food networks may help untangle the complexity of diet and biology in health and disease."

One limitation of the study was that participants completed a food questionnaire that relied on their ability to accurately recall diet rather than having researchers monitor their diets. Another limitation was that diets were only recorded once, years before the onset of dementia, so any changes in diet over time were unknown.

https://www.sciencedaily.com/releases/2020/04/200422214038.htm

Eating a vegetarian diet rich in nuts, vegetables, soy linked to lower stroke risk

February 28, 2020

Science Daily/American Academy of Neurology

People who eat a vegetarian diet rich in nuts, vegetables and soy may have a lower risk of stroke than people who eat a diet that includes meat and fish, according to a study published in the February 26, 2020, online issue of Neurology®, the medical journal of the American Academy of Neurology.

"Stroke is the second most common cause of death worldwide and a leading cause of disability," said study author Chin-Lon Lin, M.D., of Tzu Chi University in Hualien, Taiwan. "Stroke can also contribute to dementia. If we could reduce the number of strokes by people making changes to their diets, that would have a major impact on overall public health."

The study involved two groups of people from Buddhist communities in Taiwan where a vegetarian diet is encouraged, and smoking and drinking alcohol are discouraged. Approximately 30% of participants in both groups were vegetarians. Of the vegetarians, 25% were men. Researchers defined vegetarians as people who did not eat any meat or fish.

At the start of the study, the average age of all participants was 50 and none had experienced stroke. The first group of 5,050 people was followed for an average of six years. The second group of 8,302 people was followed for an average of nine years. Participants were given medical exams at the start of the study and asked about their diet.

Vegetarians ate more nuts, vegetables and soy than non-vegetarians and consumed less dairy. Both groups consumed the same amount of eggs and fruit. Vegetarians ate more fiber and plant protein. They also ate less animal protein and fat.

Researchers then looked at a national database to determine the numbers of strokes participants had during the course of the study.

In the first group of 5,050 people, there were 54 strokes. For ischemic strokes, which are strokes when blood flow to part of the brain is blocked, there were three strokes among 1,424 vegetarians, or 0.21%, compared to 28 strokes among 3,626 non-vegetarians, or 0.77%. After adjusting for age, sex, smoking and health conditions like high blood pressure and diabetes, researchers found vegetarians in this group had a 74% lower risk of ischemic stroke than non-vegetarians.

In the second group of 8,302 people, there were 121 strokes. For both ischemic and hemorrhagic strokes, also called bleeding strokes, there were 24 strokes among 2,719 vegetarians, or 0.88%, compared to 97 strokes among 5,583 non-vegetarians, or 1.73%. After adjusting for other factors, researchers found vegetarians in this group had a 48% lower risk of overall stroke than non-vegetarians, a 60% lower risk of ischemic stroke and a 65% lower risk of hemorrhagic stroke.

"Overall, our study found that a vegetarian diet was beneficial and reduced the risk of ischemic stroke even after adjusting for known risk factors like blood pressure, blood glucose levels and fats in the blood," said Lin. "This could mean that perhaps there is some other protective mechanism that may protecting those who eat a vegetarian diet from stroke."

One limitation of the study was that the diet of participants was only assessed at the start of the study, so it is not known if participants' diets changed over time. Another limitation was that study participants did not drink or smoke, so results may not reflect the general population. Also, results from the study population in Taiwan may not be generalizable worldwide. Finally, there could be other factors, not accounted for, that might affect stroke risk.

https://www.sciencedaily.com/releases/2020/02/200228102225.htm