A new study published in the American Journal of Clinical Nutrition intensifies doubts about long-standing recommendations to avoid full-fat dairy products for a healthy heart.
The 22-year study measured blood markers of several saturated fats present in dairy products in 2,907 adults aged 65 years and older.
Over the course of the study, 2,428 of the elderly research participants died, 833 from heart disease.
It found no link between the saturated fats measured and increased risk of death from heart conditions, in fact, one was linked with lower risk.
Lead author Marcia Otto, assistant professor at the University of Texas Health Science Centre, says the research "adds to an increasing body of evidence showing no harm to heart disease or overall mortality associated with consumption of whole-fat dairy foods".
While other studies have used markers like cholesterol levels, which may not be accurate, the US researchers claim this is the first large study to use repeated measures of fatty acids over time and investigate their impact on mortality in older adults.
“This new study adds to mounting research showing that when it comes to heart disease, we may not need to be as worried about full-fat dairy foods as previously thought," says Australian nutrition scientist and accredited practising dietitian Tim Crowe.
Although the study is observational (so it can’t prove that it was the dairy foods that impacted heart disease risk), Crowe says the use of blood bio-markers rather than self-reported surveys makes it more reliable than most research in the area.
People are confused about the impact of saturated fat on health, and this is reflected in shifts away from low-fat dairy consumption.
Dairy Australia’s managing director Ian Halliday told the Senate Estimates committee this year his industry was "seeing, on a global basis, a move towards full-fat dairy products”.
However, this shift is not reflected in Australia’s dietary guidelines, which recommend low-fat dairy for people over two years of age.
"Dietary guidelines undergo revision with new research considered at each stage," says Crowe.
"So advice about low-fat dairy will be one area closely looked at in the future taking into account research such as this current study."
Otto says making judgements about food healthfulness based on nutrient content alone may lead to confusion and misinformation.
"Foods are more than their single nutrient content, and dairy foods are particularly rich in essential nutrients such as calcium and potassium.”
Crowe agrees, saying “people eat food, not nutrients”.
On balance, he says the health effects of dairy are rather neutral, adding that “just eating low-fat dairy foods on their own will not do much to address a poor diet low in many beneficial plant-based foods”.
Last year an international expert panel published a consensus that current evidence does not support connections between dairy products and heart disease, while fermented dairy products, such as cheese and yoghurt, generally have positive links with health.
Although, speaking to professionals, many seem reluctant to recommend full-fat dairy.
Nutrition expert Robyn Chuter says nutrients provided by dairy foods are also readily available in other foods like green leafy vegetables, legumes, nuts and seeds, which provide ample amounts of calcium, as well as other important minerals like potassium.
Heart Foundation spokesperson and accredited practising dietitian Beth Meertens says she recommends low-fat dairy.
For Meertens, foods with proven benefits – including vegetables, fruits, nuts, legumes, and healthy oils like olive oil – should be the primary focus for heart health.
Similarly, while dietary guidelines have shifted away from nutrients towards recommending food groups, they still advise people to avoid foods containing saturated fat.
This is based on the enduring notion that saturated fat causes atherosclerosis (plaque build-up in the arteries, and a primary cause of heart disease).
A 2016 editorial in the British Journal of Sports Medicine by Aseem Malhotra from the UK Academy of Royal Medical Colleges questioned this assumption saying "the conceptual model of dietary saturated fat clogging a pipe is just plain wrong".
Malhotra and his co-authors argue that inflammation is the real culprit, citing several reviews and meta-analyses have shown no links between saturated fat and heart disease.
One study measured associations between diet and biological progression of atherosclerosis in over 200 post-menopausal women with heart disease.
Carbohydrates and polyunsaturated fats were linked to greater progression of their disease, but not saturated fat.
Reviews support links between refined carbohydrates, rather than saturated fat, and heart disease risk.
And evidence suggests that while whole grains show positive health outcomes, low carbohydrate diets might reduce inflammation.
To reduce risk of heart disease and improve quality of life, Malhotra recommended the best approach is “a complete lifestyle approach of a healthful diet, regular movement and stress reduction”.