Doctors today pride themselves on practicing “evidence-based medicine.” That means using the best scientific data derived from research to make recommendations for policy and treatment.
When it comes to diet and nutrition, however, old beliefs die hard. Even when the evidence contradicts dietary dogma, health professionals may cling to outdated recommendations.
For nearly fifty years Americans have been warned to back away from butter, minimize meat and skimp on salt. This so-called healthy diet was supposed to protect us from heart attacks, strokes and other health problems like hypertension, diabetes and obesity. It turns out that these dietary guidelines were not based on solid scientific research. The recommendations did not reduce cardiovascular disease, diabetes or obesity. If anything, the twin epidemics of diabetes and obesity are far worse today than when the guidelines were issued.
The Straight and Skinny on Saturated Fat
A recent meta-analysis indicates that the dietary advice in the 1977 US guidelines to cut fat intake, especially saturated fat, was not supported by the findings from randomized controlled trials that were available at that time (Open Heart, online Feb. 9, 2015). This led the authors to remark that:
“It seems incomprehensible that dietary advice was introduced for 220 million Americans and 56 million UK citizens, given the contrary results from a small number of unhealthy men.”
Saturated fat has remained the main dietary villain for heart disease for over 50 years. Last year a meta-analysis of 72 studies with more than 600,000 participants determined that there was no association between how much saturated fat people ate and their risk of having a fatal or nonfatal heart attack (Annals of Internal Medicine, March 18, 2014).
Another study published in the Journal of Nutrition (Feb. 2015) spent almost five years following over 2,000 people with diagnosed heart disease. The volunteers filled out detailed questionnaires about their dietary habits at the beginning of the study. The conclusions were:
“There was no association between dietary intake of SFAs [saturated fatty acids] and incident coronary events or mortality in patients with established CAD [coronary artery disease].”
Such studies make headlines because they challenge traditional medical advice. One might expect that health policy would change based on the latest scientific evidence.
Don’t hold your breath. As soon as the newspapers are recycled, nutrition experts will be back to telling us all that saturated fat will harm our hearts. Never mind that the data do not support this belief.
New 2015 Dietary Guidelines Just Released
On February 19, 2015, the United States Department of Agriculture (USDA) announced that its Dietary Guidelines Advisory Committee had submitted a new report on what Americans should and should not be eating. It should not surprise you to learn that the new guidelines recommend that people avoid saturated fat. The panel of experts advises that:
“Sources of saturated fat should be replaced with unsaturated fat, particularly polyunsaturated fatty acids…”
In other words, little, if any, red meat, butter, cheese or whole milk and more vegetable oils like corn or safflower oil. The trouble with the new recommendations is that once again they have embraced belief over science. It is possible that eliminating meat, butter, cheese and full fat yogurt would be good for our health, but until there are large, long-lasting clinical trials to test this concept, there is little data on which to base this advice. By the way, there is growing evidence that a diet rich in polyunsaturated oils may be pro-inflammatory.
2015 Food Guideline Flip-Flops
Cholesterol Is No Longer Bad
The most impressive reversal in the new dietary guidelines is the elimination of the prohibition on cholesterol. For decades Americans have been exhorted to cut back on eggs and other foods that were high in this substance. Shrimp, lobster and chicken livers were verboten along with meat and cheese. Now the experts almost admit in their new report that it was all a mistake. Actually they they use stuffy scientific language to say that cholesterol never really mattered and there were no data to support the old dietary dictums. Part D of Chapter 1 on page 17 states:
“Previously the Dietary Guidelines for Americans recommended that cholesterol intake be limited to no more than 300 mg/day. The 2015 DGAC (Dietary Guidelines Advisory Committee) will not bring forward this recommendation because available evidence shows no appreciable relationship between consumption of dietary cholesterol and serum cholesterol, consistent with the conclusions of the AHA/ACC (American Heart Association/American College of Cardiology report. Cholesterol is not a nutrient of concern for overconsumption.”
OK, did you catch the big challenge? The new guidelines fly in the face of the cholesterol demonization by the American Heart Association and the American College of Cardiology. Have you ever wondered how much cholesterol is in one egg? Depending of course on the size of the egg, you could get over 200 mg. Two eggs would push you over the day’s allowable limit of 300 mg. The new guidelines admit this limit was without scientific support and basically eliminate cholesterol restrictions.
What About Salt?
Like saturated fat, sodium chloride has been labeled a killer. The American Heart Association is adamant that “all Americans reduce the amount of sodium in their diet to less than 1,500 mg a day.”
The Institute of Medicine, the country’s most prestigious medical organization, published a report last year noting that there is a lack of evidence supporting low-sodium guidelines (JAMA Internal Medicine, Jan. 2014). A meta-analysis of 25 studies found that people with the lowest salt consumption actually had an increased risk of death (American Journal of Hypertension, Sept., 2014).
The new dietary guidelines also take issue with the American Heart Association and the CDC when it comes to salt. Instead of recommending less than 1,500 mg of sodium daily, the report suggests that 2,300 mg is a more reasonable target.
Bottom Line
The Dietary Guidelines Advisory Committee has made some interesting progress with its new recommendations. The panel strongly urged Americans to cut back on sugar. At last we are hearing from nutrition experts that sugar is in fact contributing to many of our health problems including diabetes and obesity.
Hmmm. That’s something physicians knew over 100 years ago, but somehow it was forgotten in our low-fat fanaticism. Many of the low-fat foods of the 1990s had added sugar to make them more palatable.
The idea that we should eat more vegetables was something that our grandmothers used to encourage, so we’re delighted that the new dietary guidelines encourage that.
We are disappointed, however, that saturated fat is sill labeled a dietary demon. Until there is actual evidence that butter is bad and that cheese is a killer, we’re not on board with the new recommendations. Ask any Frenchman if margarine is a healthy substitute for butter or whether you should avoid Brie and Camembert and you will be laughed out of town. By the way, the French, who ignored our advice to cut back on cholesterol and shun saturated fat have less coronary heart disease. This is the so-called French paradox.
In this era of evidence-based medicine, dietary guidelines need to change to keep up with the latest scientific research. We are glad to see the flip-flop on cholesterol in the latest report. But the public health policy makers at the American Heart Association, the American College of Cardiology and the CDC will lose credibility if they continue to base their recommendations on unsubstantiated beliefs rather than on evidence.
You can read more about other dietary approaches to keeping your heart healthy in our book, Best Choices From The People’s Pharmacy.
