WHEN Michigan State University assistant professor Dr. Adam Lock opened a letter from his child's school explaining its dietary program, a sentence describing "healthy" snacks stopped him in his tracks.
In the letter, the words "low-fat" — in accordance with U.S. Department of Agriculture guidelines — appeared before "dairy foods."
Still, one sentence not mandated by USDA had Lock, who was raised on a dairy farm and is an expert in dairy nutrition, shocked to see such a misleading statement. The letter claimed that "cheese is the number-two source of heart-damaging saturated fat in children's diet."
Unlike Lock, most parents would not object to the statement because, for more than 50 years, the concept of eating healthy had become synonymous with avoiding fat, especially saturated fat.
Now, Lock told an American Feed Industry Assn. conference in St. Louis, Mo., the public has a fear of fat.
"Unfortunately, current public perception and public policy is that milk fat, as a saturated fat, is bad for human health," Lock explained. "For over a half-century, saturated fat has been demonized as the major cause of cardiovascular disease (CVD), and public health recommendations are to reduce dietary intake of saturated fat and food products containing saturated fatty acids."
In 1953, scientist Ancel Keys played a fundamental role in labeling saturated fat as the cause of heart disease and rising cholesterol levels. His diet/heart theory was widely accepted and taken for truth after he appeared on the cover of Time magazine. This led to a widespread fear of saturated fat and the characterization of milk fat as evil.
Over the years, Keys' diet/heart theory has been challenged by the scientific community, and many flaws have been found in his data.
Initially, plasma cholesterol level was considered the main risk factor in CVD. After 50 years of research and reviewing the history and politics behind the diet/heart theory, it has become clear that the relationship among fats, cholesterol and health is complex.
Today, advances in technology and research have identified 270 risk factors for CVD, with genetics being the foremost factor.
Milk fat complexity
When looking at the major contributors of saturated fat in U.S. diets, milk and dairy products are often cited as the major source, but in fact, vegetable, non-animal sources are the highest contributor, at 44%.
"There is no getting away from the fact that milk fat contains a high portion of saturated fatty acid because of ruminant metabolism and ruminant biohydrogenation," Lock said. "No matter what we do or what we feed the cow, milk fat is always going to be prominent in saturated fatty acids."
Milk can contain 60-75% saturated fat. Milk fat is, by nature, the most diverse fat matrix, containing more than 400 different fatty acids.
The complexity of milk fat composition often leads to misunderstanding and public confusion; therefore, a generalization about fat and fatty acid is declared.
The Nutrition Committee of the American Heart Assn. recommended that the nutritional value-based and biological effects of individual fatty acids be evaluated.
Research on milk's composition has shown that saturated fat increases total and low-density lipoprotein cholesterol but also raises high-density lipoprotein, thus having a neutral effect on circulating cholesterol, explained Lock.
Dairy in the diet
"It's important to recognize that individuals consuming dairy fats don't consume just saturated fat," Lock said.
As a nutrient-rich food, milk and dairy products are an important source of many vital nutrients — including high-quality protein, calcium and many essential minerals and vitamins — for maintaining a healthy diet.
All calories are not created equally. An 8 oz. cup of milk provides nine essential nutrients, and it is a top food source for calcium, vitamin D and potassium, which are missing in the diets of most adults and children.
Lock noted that future research needs to focus on answering the question of whether reduced-fat milk and dairy products truly provide any additional advantages over whole milk.
Mounting scientific evidence and recognizing that not all saturated fatty acids have the same biological effects could change current dietary recommendations and the public perception of dairy fats in the human diet. Lock warned that change could be slow since the current public perception has been two to three generations in the making.
Lock added that all milk should be promoted as being a significant contributor of nutrients and having benefits for human health.