Why we can’t trust data from the Correlational Study of Diet and Health

A new study from the American Dietetic Association (ADA) has found that people who eat a lot of meat, poultry and fish are less likely to get dementia. 

The study was conducted by researchers at the University of California, San Francisco (UCSF), and the California State University, Los Angeles (CSULA).

The results are the first to show that meat consumption and other dietary factors are strongly associated with the risk of developing dementia, the ADA said in a statement. 

This is the first longitudinal study of dementia risk in adults in the United States, and it is an important step toward establishing a baseline measure of risk and assessing how to adjust it as new research emerges about dementia risk.

“While the findings are encouraging, we should not assume that meat and other foods are completely benign.

We must continue to monitor dietary and lifestyle factors to make sure they do not become protective,” said ADA spokesperson Katie Zebrowski. 

Researchers at UCSF’s College of Agriculture, Food, and Natural Resources (CFON) examined data from more than 10,000 people between the ages of 60 and 95. 

“We found that meat intake and other lifestyle factors were strongly associated for the first time with the onset of dementia, suggesting that people with moderate or low meat intake have a lower risk of dementia,” said co-author Dr. Randal R. Kline, a senior lecturer in the Department of Preventive Medicine at UCSB. 

Previous research found that the risk for dementia increased with meat consumption. 

But the ADA study found that, on average, people who ate a lot more meat were more likely to develop dementia.

The researchers also found that a higher level of meat consumption also appeared to increase the risk. 

According to the ADA, a diet high in meat and processed meats is associated with higher levels of the biomarkers of oxidative stress, inflammation, and oxidative stress in the blood. 

For example, red meat and meat products that are high in saturated fat are linked with higher risks of developing cardiovascular disease. 

Dr. Klines co-authored the study with Dr. Matthew R. Hirsch, associate professor in the department of psychiatry at UCSA.

“We wanted to see if there was a relationship between meat consumption, other dietary risk factors and dementia risk,” he said. 

Consequently, researchers assessed a broad range of meat and lifestyle variables, including physical activity, physical activity level, alcohol consumption, cigarette smoking, obesity, body mass index (BMI), and alcohol consumption at the beginning of the study. 

They also assessed participants’ risk of being diagnosed with dementia.

Participants were followed up for a minimum of 12 years, and their dementia risk was assessed at the end of the 12-year follow-up period. 

Among the 12,086 participants, 5,856 developed dementia, which is an average of about 3.7 dementia cases per 100,000 participants. 

When all factors were considered, those with higher meat consumption had a 1.3-point higher dementia risk than those with lower meat consumption: 1.7 for those who consumed a little more than 1.5 servings of meat per day; 1.6 for those eating 2-3 servings; 1,7 for the average person; and 1.8 for those consuming 4-5 servings per day. 

In contrast, those who ate more than 5 servings per week had a 2.1-point lower risk: 2.0 for those in the highest quartile of meat intake; 1 in the lowest quartile; and 0.8 in the middle. 

People with a higher BMI and higher alcohol consumption were at a greater risk for developing dementia: Those in the overweight category had a 3.1 point higher risk, and those in normal weight had a 4.0-point greater risk.

The ADA study also found no relationship between diet and cardiovascular disease risk.

People who were older, had lower blood pressure, and had lower levels of HDL cholesterol were at increased risk of cardiovascular disease compared to younger, healthier people.

“This research has important implications for people who are trying to manage their risk of Alzheimer’s disease,” Dr. Hisch said.

“For example: We know that cardiovascular disease is a risk factor for dementia.

We also know that people living in high-income countries are more likely than others to have cardiovascular disease.” 

In the meantime, the research is helpful in helping people understand the role of certain dietary factors in dementia, and is one step toward developing new approaches to preventing dementia.