Study suggests processed red meat, such as sausages, could increase risk of dementia

People who eat a lot of processed red meat, such as sausages, baloney or bacon, may have a higher risk of developing dementia later in life, according to a paper published in the journal Neurology. The risk of dementia was measured in a group of 133,771 people with an average age of 49 at the start of the study, who were followed for up to 43 years. Of the initial group, 11,173 people developed the disease. “Higher intake of red meat, particularly processed red meat, was associated with a higher risk of developing dementia and worse cognition,” says the study.

As a percentage, people who were in the group that ate the most processed red meat, starting from about two portions (of just under 100 grams) per week, had a 13% higher risk of dementia than those who ate less than three portions per month. Although the study is observational and cannot establish a cause-effect relationship, the results suggest that, in a country like Spain, reducing the consumption of processed red meat at a population level and replacing it with legumes or chicken would reduce the cases of dementia by tens of thousands.

In the same study, there was no significant association between consumption of red meat, such as pork or beef steaks, and increased risk of dementia or other objective measures of cognitive decline. There was, however, a 16% increased subjective risk of cognitive decline (as measured by a self-reported questionnaire) for people who ate seven or more servings of meat a week, compared with those who ate fewer than three. Although their results found no significant harm from unprocessed red meat, senior study author Dong Wang of Brigham and Women’s Hospital in Boston points to risk factors in consuming it: “It’s high in saturated fat, and has been shown in previous studies to increase the risk of type 2 diabetes and heart disease, both of which are linked to poorer brain health.”

One key to changing habits is to think about what you want to achieve rather than what you want to avoid. Because you can only eat so much, instead of restricting red meat, whether processed or not, you can consider adding more healthy foods to replace it. The study’s authors looked at the results of replacing one serving of processed red meat a day with other foods. If replaced with fish, they estimated a 28% reduction in the risk of dementia, 19% for nuts and legumes, and 16% for chicken.

Jordi Salas-Salvadó, professor of nutrition at the Rovira i Virgili University in Spain, who was not involved in the study, is not surprised by the results. “When we talk about cardiovascular disease, there is enormous evidence, but in dementia and cognitive decline, the mechanisms are very similar. Red meat has a lot of saturated fats and that increases cholesterol, which has many effects on cardiovascular risk factors and promotes the accumulation of arteriosclerosis plaque, but it also has direct effects on neurotrophic factors [which promote the survival and development of neurons],” he explains. “Meat, not only processed meat, has carnitine, which is associated with an increase in TMAO, which is a molecule produced by bacterial flora and, in addition to increasing the risk of cardiovascular disease or arteriosclerosis, it affects the expression of multiple proteins that intervene in the neuronal synapse,” he adds.

The authors of the study also offer some mechanisms that would explain why excessive consumption of red meat can damage the brain. Other studies have shown that these foods can induce insulin resistance, which affects cortical activity and is associated with excessive insulin production in the pancreas. This is related to the accumulation of beta amyloid protein in the brain, one of the mechanisms that are related to Alzheimer’s. Regarding processed meat, they point out the presence of compounds such as nitrites, used to improve the preservation or flavor of products such as ham or sausages, which can induce oxidative stress and promote inflammation, causing neurotoxic effects.

The study published in Neurology acknowledges that previous investigations had obtained results that do not coincide with theirs. A study with participants from the UK Biobank observed that an increase of 25 grams per day in the consumption of processed meat was associated with a 44% increase in the risk of dementia and a 52% increase in the risk of Alzheimer’s. However, that same study observed that the greater consumption of unprocessed red meat seemed to reduce the risk of dementia and Alzheimer’s. Another study, carried out in Germany with 2,622 participants, did not observe an association between the consumption of sausages and memory deterioration or Alzheimer’s, something that Wang and his colleagues attribute, speculatively, to the fact that the average age of the volunteers, 81.2 years, made them too old to see that association. Regarding the British study they suggest that the follow-up time, of less than eight years, and the fact participants only had an initial evaluation of their diet, may explain their data.

Wang believes that the study’s results indicate that the recommendation to “reduce the amount of red meat a person eats and replace it with other sources of protein and vegetables could be included in guidelines for diets that promote cognitive health,” although he acknowledges that more research is needed to confirm these findings in more diverse groups. The participants in this study come from two U.S. cohort studies made up of health professionals. Salas Salvadó agrees that “we must reduce the consumption of processed foods, which are providing us with quantities of salt, saturated fats, sugars and other substances that are harmful, and also reduce the consumption of red meat and try to consume more fruit, vegetables, legumes, nuts, olive oil and everything that is typical of the Mediterranean diet.” It is not about eliminating red meat from the diet, but rather making more moderate use of a product that for millennia was very scarce and now takes up too much space in diets that should be more diverse.

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