It appears that soured whole milk rather than low-fat reduces the risk of blood clots

Research results now suggest that the intake of soured whole milk products rather than low-fat soured milk products and cheese, buttermilk or milk (regardless of fat percentage) may be associated with a lower risk of thrombosis in the brain.

In a population study published in the European Journal of Epidemiology, researchers from the Department of Public Health show that adults who consume relatively more soured whole milk products than milk, have a statistically lower risk of suffering a thrombosis in the brain than adults who drink relatively more milk. Choosing soured whole milk products rather than, for example, skimmed milk/semi-skimmed milk is connected with a 15 per cent (95% safety interval 1%-26%) lower immediate risk.

"Statistically, it is our best suggestion for the risk of thrombosis in the brain, when we look at different ways to combine your intake of dairy products. We can see a 16 per cent lower immediate risk of thrombosis in the brain among those who, for example, choose high-fat soured milk products rather than whole milk. If people choose low-fat soured milk products instead of the high-fat, we see a twenty per cent higher immediate risk of blood clots. This may actually be as high as 45 per cent. However, due to the statistical uncertainty, we cannot rule out that it is a single per cent lower," say PhD student Anne Sofie Dam Laursen and Associate Professor Marianne Uhre Jakobsen from the Department of Public Health, Aarhus University.

"The result is not quite what we had expected. We had mostly expected that semi-skimmed milk was a better choice than full-fat yogurt in relation to this risk."

Looked at the whole products

The method behind the study is new because the researchers have compared people with the same total intake of dairy products, but with a specified difference in the intake of whole milk and whole milk yoghurt.

The study does not say anything about whether the individual nutrients in the products play a role in the risk of the specific disease, or whether the fact that soured milk products have added bacteria cultures and are thus processed has any significance.

"In other words, we look at the significance of eating the whole product – not whether it is the product’s content of calcium, salt, fat and so on that makes a difference. Of course, we eat all these things together when they come out of the carton", say the researchers.

The products that their data deals with stem from the mid-nineties: low-fat milk (skimmed and semi-skimmed), full-fat milk (whole milk) and buttermilk, together with Danish soured milk products (yoghurt, A38 and Ylette) with 3.5 and 1.5 per cent fat content, respectively.
When studying the correlation between dietary habits and the development of thrombosis in the brain, researchers follow the participants over many years with a view to registering the level of ill health. In the meantime, certain products ceased to be produced and new products arrived on the market.

"But the products fall into the same main categories as today, and we can see that different things happen with those who consume high-fat soured milk products rather than other dairy products, in particular milk," says Anne Sofie Dam Laursen.

Cannot provide recommendations about what to put in the fridge

These differences are probably not due to the participants eating different amounts of other foods, as the study has also compared their intake of red meat, processed meat (e.g. cold meats), fruit, vegetables and fish.

Neither is it due to differences in smoking habits, alcohol habits, obesity and educational level, which the researchers have also taken into consideration.

"But even though our result points in a specific direction, one study is obviously not sufficient grounds to publicly recommend that people change the items they have in their fridges," emphasises Anne Sofie Dam Laursen.

 Background for the results:

• The data in the population study comes from the cohort "Diet, Cancer and Health" which the Danish Cancer Society are behind.
• The questionnaire-based surveys comprise responses from 57,000 Danes aged between 50 and 64.
• None of the participants had had a thrombosis in the brain when the study began. But in the course of the follow-up period, 2,272 of the participants suffered a stroke – including 1,870 who suffered a thrombosis in the brain (ischemic stroke), while 389 suffered a cerebral haemorrhage.
• The study is financed by Innovation Fund Denmark.
• In Denmark, there are approx. 10,000 new cases of thrombosis in the brain annually.
• See the abstract of the article “Substitutions of dairy product intake and risk of stroke: a Danish cohort study”   

Contact

PhD student Anne Sofie Dam Laursen
Department of Public Health, Aarhus University
Mobile: (+45) 2184 4284
asdl@ph.au.dk

Associate Professor Marianne Uhre Jakobsen
Department of Public Health, Aarhus University
Mobile: (+45) 4141 0621
muj@ph.au.dk