This month’s blogs are a dive into the book “Good Calories, Bad Calories”. Author Gary Taubes gives an unbiased run through of many of the nutrition standards we grew up with. We will take a look into the many nutrition fads and opinions that have been passed through history with no regard to the science behind them. Today we will go through The Fat-Cholesterol Hypothesis.
Starting off with some history in 1924 the American Heart Association (AHA) was founded due to the rising number of people dying from heart disease. During that time it was a “private organization of doctors” meaning that these few doctors called what was good and what was bad regarding heart health. In the 1950’s we saw premature deaths from infectious disease and nutritional deficiencies drop which left more Americans living long enough to die of chronic diseases such as cancer and heart disease. Thus, the Diet-Heart Hypothesis was born. This hypothesis stated dietary fat causes heart disease which led to low-fat diets, and their products, being introduced. The relationship between dietary fat, cholesterol, and heart disease is more complicated than just cutting out parts of your diet. The Diet-Heart hypothesis constitutes three independent propositions: 1. Lowering cholesterol prevents heart disease, 2. Eating less fat or less saturated fat not only lowers cholesterol and prevents heart disease but 3.That it also prolongs life. In the 1960’s deaths from coronary heart disease appeared to decline after peaking. This peak was due to clinicians becoming more aware in recognizing cardiac disturbances and recording them more frequently, however, authorities said it was somewhat due to the preventative benefits of eating less fat and lowering cholesterol. The AHA used scare tactics to force the public to eat low-fat so they wouldn’t die of heart disease. In the 1970’s, a study found that the vegetable oils and margarines (polyunsaturated) the AHA were recommending as replacements (because they had an alliance with the companies who made them) caused cancer in lab animals.
Now let’s get into science vs corporations and government. Establishing the dangers of cholesterol in our blood and the benefits of low fat diets has always been portrayed as a struggle between science and corporate interests. A question was asked of why so many people suffer coronary heart disease despite having low cholesterol and why multitudes of people with high cholesterol never get or die from heart disease. Any research that was not in favor of the low-fat-diet hypothesis was deemed irrelevant, misinterpreted, or based on untrustworthy data. Unfortunately, if science doesn’t fit the dogma it either gets ignored or never cited, but not invalidated. The reason we still see low fat diets being popularized is truly due to its advocates inability to recognize or acknowledge error, rather than evidence. When working for corporations or government scientists are supposed to be free of conflict and bias. Based on funding, if a group of scientists' research failed to support the government positions then the funding would go to someone whose research did. Now we have the dilemma if a study is correct and has no funding will the public take it seriously or will they listen to the scare tactics used by big corporations to make the risks of “unhealthy” behaviors seem detrimental.
The USDA is a government funded organization. When they first came out with the Dietary Recommendations the statistics used were based on guesses not reliable evidence. They took a bunch of speculation, acknowledged the claims were science, and then decided they were fact. The Dietary Goals gave way to other government agencies giving dietary advice and the document became the end all be all. Though the Dietary Goals admitted the existence of scientific controversy, it also insisted that Americans had nothing to lose by following the advice. The question to be asked is not why should we change our diet but why not. The committee eventually published a revised edition of Dietary Goals, but with only minor revisions. Now the first recommendation was to avoid being overweight.
Finally we dig into cholesterol. Cholesterol is a pearly white fatty substance that is found in all body tissues and is an essential component of cell membranes and physiological processes including metabolism and sex hormones. Many circumstances influence total cholesterol levels: exercise will lower it, weight gain will raise it, weight loss will lower it, stress will raise it. The levels will fluctuate seasonally and change with body position. Hormones will affect levels as well as diuretics, sedatives, tranquilizers, and alcohol. For these reasons alone, cholesterol levels can change by 20-30% over the course of weeks. The cholesterol we eat has very little effect on the amount of cholesterol in our blood. The fats we do eat (animal and vegetable) are composed of many different kinds of fats, each with its own chain length and degree of saturation, and each with a different effect on cholesterol. Our brains are 70% fat, mostly in the form of a substance known as myelin that insulates nerve cells and all the nerve endings in the body. Fat is the primary component of all cell membranes. Changing the proportion of saturated to unsaturated fats in the diet, might change the composition of the cell membranes. This could alter the permeability of cell membranes, which determines how easily they transport, among other things, blood sugar, proteins, hormones, bacteria, viruses, and tumor-causing agents into and out of the cell. The relative saturation of these membrane fats could affect the aging of cells and the likelihood that blood cells will clot in vessels and cause heart attacks. Lower cholesterol by diet might help prevent heart disease for some, but it also may raise susceptibility or even cause other conditions such as stroke and cancer. Most of the studies done on cholesterol have involved men. With the few studies involving women, it was found that the higher the cholesterol the longer they lived and this could be due to our sex hormones needing more of the fat to run our systems properly.
Stay tuned for Part 2!
