Could eating a diet rich in full-fat dairy reduce the risk of metabolic syndrome – a cluster of risk factors, including abdominal obesity, insulin resistance, high blood pressure and high cholesterol, that increases the risk of heart disease, diabetes and stroke?
Dr. Mario Kratz, a researcher in the Public Health Sciences Division at Fred Hutchinson Cancer Research Center, hypothesizes it could be true, and he recently received more than $1 million from a consortium of five international dairy organizations led by the National Dairy Council to conduct a randomized clinical trial to find out.
The potential link between full-fat dairy and reduced risk of metabolic syndrome “certainly is counterintuitive,” Kratz said, “which is why I think we may have missed the boat on this for so long.”
Dairy fat contains more than 400 different fatty acids, some of which are known or suspected to help oxidize, or burn, fat in the liver while simultaneously blocking the formation of new fat. Full-fat dairy products – particularly fermented ones, such as cheese – also are among the best food sources of vitamin K2, which has been linked to better glucose tolerance and lower risk of cardiovascular disease.
Alcohol and certain carbohydrates – particularly fructose – in contrast, are converted to and stored as fat in the liver. While having some fat in the liver is normal, if more than 5 to 10 percent is fat, the condition is called fatty liver disease, a risk factor for glucose intolerance and, eventually, type 2 diabetes. Fatty liver is also a major risk factor for liver disease, including cirrhosis and liver cancer.
An estimated 20 percent of the U.S. population has fatty liver disease, which, despite its potential long-term health consequences, typically has no symptoms.
An observational study conducted by Kratz and colleagues, published last year, was the first to find an inverse association between dairy fat consumption and the amount of fat in the liver.
“We are now the first to investigate, in a randomized controlled trial, whether a causal effect actually underlies this observed association,” Kratz said. If his hypothesis is correct, it could reverse decades of assumptions about the role of dairy fat on health.
“For 30 or 40 years, the assumption was that if we consume dairy foods in their full-fat form, that would raise our LDL [low-density lipoprotein, or so-called ‘bad’ cholesterol] and our risk of cardiovascular disease. Similarly, the thinking was that the extra calories from the dairy fat would make us overeat and gain weight,” he said. “I will admit these are very plausible assumptions; however, none of these assumptions are actually supported by any evidence.”
A review article Kratz authored two years ago reported that people who eat more full-fat dairy tend to have less weight gain than those who consume fewer full-fat dairy products, an observation that was not true for people who consume more versus fewer low-fat dairy options. Several large studies also have suggested an inverse relationship between dairy fat consumption and the risk of type 2 diabetes and cardiovascular disease.
A possible explanation for this inverse relationship, Kratz, cautioned, is that people who are already obese or gain weight easily are more likely to stay away from perceived “obesogenic” foods, or foods thought to promote weight gain. “A major concern in observational studies is that so-called ‘reverse causation’ could underlie the observed association,” he said. Randomized trials are needed to separate the hypothetical observations from the facts.
“Again, we may perceive this as counterintuitive, but based on some insight we have recently gained from basic scientific experiments in animal models, it is no longer implausible to hypothesize that dairy fat may have health benefits. Given that dairy foods make up a significant portion of foods consumed in the U.S., learning more about this topic could have a tremendous impact on public health,” he said.
For the study, Kratz will recruit 72 men and women with metabolic syndrome. All participants will first complete a three-week no-dairy diet. They will then be randomly assigned to one of three 12-week dietary interventions:
The dairy products will be weighed, packaged and distributed to study participants via Fred Hutch’s Human Nutrition Lab. Other than the presence or absence of dairy, participants will be asked to follow their regular eating patterns.
“We are aiming to study a real-life situation where participants incorporate different amounts and types of dairy into their normal diet,” Kratz said.
In addition to funding from the National Dairy Council, the Fred Hutch Reservoir Fund has provided approximately $500,000 for the three-year study, which will begin recruitment this summer.
“Given that dairy products are consumed daily by most Americans, [this study] could have tremendous long-term consequences for the population at risk of type 2 diabetes and other conditions linked to metabolic syndrome and fatty liver disease,” Kratz said.
Editor’s note: The National Dairy Council will not be involved in the conduct of the trial, the analysis or interpretation of the data or the decision to publish the results, said Kratz, who initiated the project and made all final decisions regarding the study design.
Dr. Scott Ramsey, director of the Hutchinson Institute for Cancer Outcomes Research, or HICOR, wrote an editorial for the April issue of Health Affairs about factors behind the escalating cost of cancer drugs.
In his editorial, Ramsey makes the following observations:
Cancer drug prices are increasing at an unprecedented rate. Asking whether these drugs continue to provide value is an irrelevant question, according to Ramsey, because cancer drug prices are not set with value in mind.
Instead, skyrocketing cancer drug prices are being driven by three policy changes, all of which are fueling manufacturers’ willingness to set higher prices:
Beyond the policy factors, Ramsey asserts that the biggest factor driving cancer drug prices is a technological change – specifically, the extraordinary reductions in the cost of genomic sequencing to find potential drug targets.
Bottom line: cancer drug pricing is driven by factors that have little to do with the intrinsic value of the products themselves. Ramsey suggests that developing policies that address the uncertainty that drug makers face in a landscape of rapid technological change may provide a better solution for society than price controls.