High-Protein Foods Are Brain Healthy, High-Protein Diets Are Not

VIDEO+ARTICLE:

High-protein foods fight stroke, a major risk factor for Alzheimer's and vascular dementia. But what happens in a high-protein diet, where more protein means less of other important food?

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People with diets higher in protein, especially from fish, may be less likely to have a stroke than those with diets lower in protein, according to a meta-analysis published in the June 11, 2014, online issue of Neurology®, the medical journal of the American Academy of Neurology.

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20 Grams Per Day Reduces Risk

"The amount of protein that led to the reduced risk was moderate -- equal to 20 grams per day," said study author Xinfeng Liu, MD, PhD, of Nanjing University School of Medicine in Nanjing, China. "Additional, larger studies are needed before definitive recommendations can be made, but the evidence is compelling."

The meta-analysis looked at all of the available research on the relationship between protein in the diet and the risk of stroke. Seven studies with a total of 254,489 participants who were followed for an average of 14 years were included in the analysis.

Overall, the participants with the highest amount of protein in their diets were 20 percent less likely to develop a stroke than those with the lowest amount of protein in their diets. The results accounted for other factors that could affect the risk of stroke, such as smoking and high cholesterol. For every additional 20 grams per day of protein that people ate, their risk of stroke decreased by 26 percent.

"If everyone's protein intake were at this level, that would translate to more than 1.4 million fewer deaths from stroke each year worldwide, plus a decreased level of disability from stroke," said Liu.

Red Meat?

Liu noted that the analysis does not support increased consumption of red meat, which has been associated with increased stroke risk. Two of the studies were conducted in Japan, where people eat less red meat than westerners do and more fish, which has been associated with decreased risk of stroke.

"These results indicate that stroke risk may be reduced by replacing red meat with other protein sources, such as fish," Liu said.

The reduced risk of stroke was stronger for animal protein than vegetable protein.

Protein has the effect of lowering blood pressure, which may play a role in reducing stroke risk, Liu said.

High-Protein Diets

Many Americans follow popular diets, such as the Atkins, Zone, Protein Power, Sugar Busters and Stillman diets. Most of these diets aren't balanced in terms of the essential nutrients our bodies need. Some are high protein and emphasize foods like meat, eggs and cheese, which are rich in protein and saturated fat. Some restrict important carbohydrates such as cereals, grains, fruits, vegetables and low-fat dairy products. If followed for a long time, they can result in potential health problems. And while they may result in quick weight loss, more research is needed on their effectiveness for long-term weight loss.

These diets can cause a quick drop in weight because eliminating carbohydrates causes a loss of body fluids. Lowering carbohydrate intake also prevents the body from completely burning fat. In the diets that are also high in protein, substances called ketones are formed and released into the bloodstream, a condition called ketosis. It makes dieting easier because it lowers appetite and may cause nausea.

The Side Effects

Most Americans already eat more protein than their bodies need. And eating too much protein can increase health risks. High-protein animal foods are usually also high in saturated fat. Eating large amounts of high-fat foods for a sustained period raises the risk of coronary heart disease, diabetes, stroke and several types of cancer. People who can't use excess protein effectively may be at higher risk of kidney and liver disorders, and osteoporosis.

That's why the American Heart Association guidelines urge adults who are trying to lose weight and keep it off to eat no more than 35 percent of total daily calories from fat and less than 7 percent of total daily calories from saturated fat and less than 1 percent of total daily calories from trans fat. On most high-protein diets, meeting these goals isn't possible.

High-protein diets don't provide some essential vitamins, minerals, fiber and other nutritional elements. A high-carbohydrate diet that includes fruits, vegetables, nonfat dairy products and whole grains also has been shown to reduce blood pressure. This, in turn, reduces stroke along with lowering the risk of Alzheimer's and vascular dementia.

So focus on protein-rich brain-healthy foods, while being careful to keep the rest of your diet in balance.

Reference:

1. Zhizhong Zhang, Gelin Xu, Fang Yang, Wusheng Zhu, and Xinfeng Liu.Quantitative analysis of dietary protein intake and stroke risk. Neurology, June 2014 DOI: 10.1212/WNL.0000000000000551

SOURCES:

• American Academy of Neurology
• CBS Philly
• American Heart Association