Does eating more dairy fat reduce heart disease risk?

28 September 2021

The study, published in PLOS medicine, looked at more than 4,000 Swedish 60-year-olds. Researchers tested their blood for fatty acids found in dairy foods and over the following 16 years recorded whether they died or had a cardiac event such as a stroke or heart attack.

The researchers adjusted for other risk factors such as smoking and alcohol drinking habits, levels of physical activity, diet and diseases such as diabetes.

They found that people with higher blood levels of two types of fatty acids found in dairy (heptadecanoic and pentadecanoic) had the lowest risk of heart and circulatory diseases. Another type of fatty acid found in dairy (Trans-palmitoleic acid), wasn’t linked with reduced risk.

The study also compared results with 17 other similar studies, from the US, Denmark and the UK, which also showed that higher levels of heptadecanoic and pentadecanoic acids were linked with a lower risk of heart and circulatory diseases.

How good was the research?

A strength of this study, compared to others done previously, is that it looked at levels of fatty acids found in dairy products in people’s blood, instead of asking participants to self-report their diet, which can be unreliable.

A drawback of this method is that it doesn’t distinguish between the different types of dairy food that were eaten (such as cheese, milk, yoghurt butter and cream), which might have different health effects, so it is difficult to translate these results into specific recommendations about what you should eat.

The participants’ blood was tested only once, at the beginning of the trial, meaning the results only reflected their diet at a certain point in time.

The vast majority of people that the researchers tested were born in Scandinavia and they were all 60, so it is difficult to apply these findings to other age groups, ethnic groups, or people in other countries with different diets. However, by also including analysis of 17 other studies, and so including data from nearly 43,000 participants from other countries, the wider findings are more representative.

It’s important to remember this study was observational. It just shows a relationship between people who eat higher levels of dairy fat and a lower risk of heart and circulatory diseases. Other factors might be a play, although the researchers did adjust for some lifestyle factors. As the researchers themselves point out it doesn’t show cause and effect and more research is needed to understand how certain dairy foods might help lower the risk of heart and circulatory disease.

BHF view

BHF dietitian Tracy Parker says:

"Dairy products don't need to be excluded from the diet to prevent heart and circulatory diseases and are already part of the Eatwell guide, which is the basis for our healthy eating recommendations in the UK.

"But don’t stock up on full-fat dairy just yet. There’s unlikely to be any harm in choosing low or reduced-fat dairy products (as long as they don’t have added sugar to replace the fat) and it has a clear benefit if you have high cholesterol. Lower-fat versions of milk, cheese and plain yoghurt are also lower in energy (calories) and so can be helpful if you are trying to manage your weight."

How accurate was the media coverage?

This story was picked up by The Daily Mail, Guardian, Times and The Telegraph, among others.

Coverage was largely accurate and reported on all relevant points within the study, explaining how the study was conducted, its results, and some of the strengths and weaknesses of the study.

The Guardian, The Telegraph and Daily Mail included quotes from researchers involved in the study and other scientists, while the piece by the Times was shorter and more concise.

All the papers were careful not to use sensational headlines. They all suggested that eating more dairy fat was linked to lower heart and circulatory disease risk, rather than saying that it definitely causes lower levels of heart disease.

However, none of the papers highlighted that the study showed that palmitoleic acid (which is found in dairy products and is highest in butter in particular) was not linked with reduced heart and circulatory disease risk.

Also, the Daily Mail claimed, “Adults who consume a high dairy diet are up to 25 per cent less likely to develop heart disease,” a figure which doesn’t appear to have been drawn from the study.