In 1977, the government came out with recommended Dietary Goals for the United States. This set of recommendations was a forerunner to the first Dietary Guidelines for Americans, which were released in 1980 and every five years thereafter. The most prominent component of the Dietary Goals in 1977 was a directive to reduce fat intake (especially saturated fat) in an effort to combat heart disease, which had been on the rise and had become the leading cause of death in the country. Secondary recommendations included a reduction in dietary cholesterol and a note about decreasing sugar intake to fifteen percent of overall calories (about 300 calories per day from sugar). From these recommendations sprung a nearly thirty-year run of low-fat products and diets dominating the American food supply. At the same time, rates of obesity, heart disease, and diabetes rapidly increased. How did this happen? Were the recommendations misguided or did we err in our methods of applying them to our lifestyles? What drove the recommendation for a low-fat diet in the first place?
The recommendation to reduce fat and cholesterol intake to strict levels was driven by nutrition researcher Ancel Keys who submitted the first multi-country epidemiological study on nutrition. Calling it the Seven Countries Study, Keys found an association between saturated fat intake and heart disease in – you guessed it – seven countries, including the United States, Japan, Italy, Finland, Greece, the Netherlands, and former Yugoslavia (areas within present-day Serbia and Croatia). The correlation was quite clear, almost a linear relationship between saturated fat intake and heart disease. The research also validated a strong relationship between blood cholesterol and risk of heart attack as well as cigarette smoking being a strong predictor of increased risk of heart disease and strokes. Useful information, right?
The controversy around the study and its influence on dietary recommendations for Americans comes from a couple of places. First, Keys drew a great deal of criticism from fellow researchers for excluding several other countries from his study despite having access to data from them. These other countries did not show a similar relationship between saturated fat intake and heart disease. Added to his data, the connection between those two factors became less clear.
Others argued that Keys missed important connections in his data linking sugar intake to heart disease. It’s important to note that while the 1977 Dietary Goals did mention sugar, the recommended “limit” of around 75 grams per day was more than double what is recommended today.
Fast-forward to today. The field of nutrition science faces more hurdles now than it did then. Rates of obesity, heart disease, and diabetes are much higher than they were in 1977. Did those low-fat recommendations contribute to this? Possibly, but there are many other factors in play here.
If low-fat meant high-sugar (which it did for many people), it was not a positive change. Low-fat diet products often have sugar added to them in an effort to preserve flavor. There’s no benefit in making that trade. If a reduction of fat was replaced by an increase in plant foods (fruits and vegetables), we may have seen a different outcome.
Another major contributor to the issues we have today with body weight and chronic disease is our lack of physical activity. There was a time when we didn’t need to go to the gym to be active, when our daily lives required activity that was an inescapable part of our routine. Developments in technology have made it such that we can control our thermostat, water our lawn, and have our dishes washed all while we enjoy the comfort of our living-room recliner. Oh, and we don’t need to get up to change the channel, either. Even vacuum cleaners are self-propelled now.
You shouldn’t feel bad about being confused about nutrition messaging from the media. The messages have always been mixed. Remember the strict recommendations on dietary cholesterol? Those persisted for nearly forty years up until the most recent Dietary Guidelines in 2015 removed the 300 milligram limit and stated that “Adequate evidence is not available for a quantitative limit for dietary cholesterol”. In other words, never mind. The guidelines do comment that eating patterns that are lower in cholesterol tend to be associated with lower body weight, but imply that cholesterol itself is unlikely the reason for this.
So what does increase our risk of heart disease? A poor diet, sedentary lifestyle, obesity, and smoking cigarettes are big contributors. Unfortunately genetics can play a role, but good lifestyle choices can usually offset that. If you’re getting lots of plant foods in your diet on a consistent basis (at least three cups per day is optimal), are physically active most days of the week, maintain a healthy body weight and choose not to smoke, you’re setting yourself up for a healthier, longer life.