Diet is a modifiable risk factor for dementia. Dairy products, which vary in processing methods, fat and nutrient content, are an important component of traditional Western diets. Although they have been extensively studied for their associations with various health outcomes, their association with dementia is still debated. In a recent study published in the journal Neurology, a team of researchers led by Prof. Emily Sonestedt (Lund University, Sweden), examined the association between high-fat and low-fat dairy intake and dementia risk. The study included 27,670 adults in Sweden, who were part of the Malmö Diet and Cancer cohort. At the beginning of the study, participants were an average age of 58.1 (61% female). The participants of the cohort underwent dietary assessments at baseline (1991-1996). In order to track eating habits, participants recorded everything they consumed over one week and answered questions about how frequently they ate specific foods during the previous years, and discussed their food preparation with the researchers. Participants were then followed for about 25 years. During that time, researchers identified the number of participants who developed dementia through the Swedish National Patient Register. The first part of the study focused on the daily consumption of high-fat cheese.
The team of researchers compared participants who ate 50 grams of high-fat cheese or more per day with those who ate less than 15 grams per day. After adjusting for differences in age, sex, education and diet quality, higher consumption of high-fat cheese was associated with a 13% lower risk of dementia. For the second part of the study, researchers compared people who consumed 20 grams of high-fat cream or more per day with those who did not consume any. Researchers found that daily consumption of high-fat cream was linked to a 16% lower risk of dementia compared with consuming none. The research team also studied the relationship between dementia risk and other dairy foods. However, they found no association between dementia and consumption of low-fat cheese, low-fat cream, high- or low-fat milk, butter or fermented milk. The results highlighted that it might be more important to focus on the source of the fat rather than on the total dietary fat. However, this study has five important limitations.
The first one is that the participants lived in Sweden. Dietary habits differ between regions, and the source and the quality of the dairy are different too. For example, what the animal eats determines what is in the milk and, therefore, what is in the cheese. Dairy from grass-fed animals usually contains higher levels of omega-3 fatty acids, which are protective for the brain. The second important limitation of this study is that diet was assessed only once at baseline and changes in consumption may have occurred over the follow-up period. The third limitation is that this study did not collect detailed information on cheese and cream intake, such as specific types or ways of consuming them. The fourth one, the baseline cognitive status of participants, which is also a predictor of dementia, was not assessed either. And finally, dementia cases were identified through a registry record, therefore, any person who did not seek diagnosis may have been missed. Consequently, it is important to be very cautious about the results in this article and avoid generalising them to other populations.