People with a higher intake of dairy fat — as measured objectively by a specialized blood test — weren’t at higher risk for cardiovascular disease or death, according to a new study published in the journal PLOS Medicine.
For decades, general dietary advice — including advice for people with diabetes — has urged people to reduce their intake of saturated fats. These fats are mostly found in animal products, including red meat, poultry, and dairy products, as well as in tropical oils like coconut oil and palm oil. Other dietary sources of fat — including nuts and seeds, avocados, most plant-based oils, and fatty fish — contain mostly unsaturated fats, which are generally agreed to be “healthy fats.” But both saturated and unsaturated fats come in many different forms in different foods, so it may not be ideal to study them in the broad categories of “saturated” and “unsaturated.” Instead, looking at the health effects of specific foods containing different types of fat may lead to the most accurate understanding of what’s good for you, and what’s bad for you.
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For the latest study, researchers in Sweden looked at the effects of different levels of dairy fat consumption on the risk for cardiovascular disease and death. They did this by measuring a biomarker of dairy fat consumption — a blood test that correlates with how much dairy fat someone consumes. This may be a better way to measure dairy fat intake than asking people what they ate, since most people don’t know the actual dairy fat content of their foods or their serving sizes — and the same serving size of a food may affect a smaller person differently from a larger person. Looking at biomarkers, on the other hand, is an objective way to measure the biological effects of consuming dairy fat. The test used in the study measured the blood level of a substance called pentadecanoic acid — a saturated fatty acid found in cow’s milk that is rare in other food sources.
Higher pentadeconoic acid levels linked to lower cardiovascular disease risk
The study participants were 4,150 Swedish adults with an average age of 60.5 at the time of enrollment. Participants had their level of pentadecanoic acid measured, and were followed for an average of 16.6 years. During this time, health records showed that 578 new cases of cardiovascular disease and 676 deaths occurred among participants. After adjusting for numerous factors known to affect the risk for cardiovascular disease and death, the researchers found that higher pentadecanoic acid levels were linked to a lower risk for cardiovascular disease in a linear relationship — meaning that the risk for cardiovascular disease changed in equal proportion to their pentadecanoic acid level. Within each segment of one-fifth of participants ranked in order from lowest to highest pentadecanoic acid level, the risk for cardiovascular disease went down by an average of 25%. When it came to death from all causes, though, the lowest risk was seen close to the median pentadecanoic acid level — not in the group with the highest or lowest dairy fat intake.
The research also separately did a combined analysis of 18 different studies that looked at biomarkers for dairy fat intake and the risk for cardiovascular disease or death — including their own study looking at pentadecanoic acid levels. They found that across all of these studies, higher pentadecanoic acid levels and levels of one other biomarker for dairy fat intake were linked to a lower risk for cardiovascular disease — with an average 12% lower risk for cardiovascular disease seen in the highest compared with the lowest one-third of participants based on pentadecanoic acid level, and a 14% lower risk for the other biomarker (called heptadecanoic acid). There was no link between these biomarkers and death risk in the combined analysis of 18 studies.
The researchers mentioned a couple of limitations to both their own study and the combined analysis of 18 studies. First, measuring biomarkers of dairy fat intake doesn’t distinguish between different types of dairy foods, which may carry different risks for cardiovascular disease even if they have the same fat content — for example, milk compared with cheese. And second, both their original study and most studies in the combined analysis only measured biomarker levels at the time of study enrollment, which may not accurately reflect participants’ dairy fat intake over the entire follow-up period. Despite these limitations, the latest findings offer compelling evidence that dairy fat might not be that bad — and could even be beneficial — when it comes to the risk for cardiovascular disease and death.
Want to learn more about dairy and health? Read “Dairy Foods and Diabetes.”