For the past six decades, there has been controversy over whether saturated fats are harmful or not to our bodies. Saturated fats, from a biological standpoint, are composed of molecules that do not have double bonds between carbon molecules because they are saturated with hydrogen molecules. In general, cell membranes are composed of protein, cholesterol, phospholipids, and carbohydrates. Fat is one of the primary components of cell membranes. Changing the proportion of saturated fats to unsaturated fats in our diets can lead to change in the cell membrane’s permeability. This may cause many problems to the cell, such as transporting hormones and signaling proteins into and out of the cell. Over fifty years ago, Ancel Keys, a physiologist who studied the influence of diet on health, started advocating for a low-fat diet. He believed that dietary fats were considered unhealthy and lead to heart disease. Then the study evolved to correlate high dietary fats with high cholesterol, which leads to coronary heart disease. Over the years, the science of fat and cholesterol escalated from a simple story to a complicated one. The question of whether eating less fats would lower cholesterol, prolong life, and decrease the chance of having heart disease is still being studied today and remains stubbornly ambiguous.
The Origin of the Controversy of Saturated Fats
The consumption of saturated fats has been seen as a health problem based on an over 50-year old study that found a correlation between elevated blood cholesterol and saturated fat in meat or dairy products. These conditions can lead to a disease called atherosclerosis, which is “when cholesterol clogs arteries,” and can lead to heart attacks (Taubes). After this study, Americans’ average fat intake decreased over time but with no evidence of improved health. This made saturated fats a hot topic in the public and encouraged scientists to do research to fill in the gaps. However, later 1969, there was a study about fats in the brain that reported, “eating less fat could have profound effects throughout the body many of which could be harmful,” since the brain can use its fats to insulate neurons (Taubes). For the first time, in the early of 1970s, “NIH opted to forgo a $1 billion trial that might be definitive and instead fund a half-dozen studies at one third the cost, everyone hoped these smaller trials would be sufficiently persuasive to conclude that low-fat diets prolong lives” (Taubes). However, the results of the studies were published between 1980 and 1984, and did not show that people who ate less fat lived longer or had fewer diseases, such as coronary heart disease. In other words, the results suggested that eating less fat might shorten a person’s lifespan. These radical results led investigators to not believe the findings of their own study, and they concluded that “methodological flaws” had led to the negative results.
After a very long debate, NIH hosted a “Consensus Conference,” the goal of which was to listen to two days of testimony about saturated fatty acids, and then arrive at a unanimous conclusion. Some of the speakers believed that all levels of “blood cholesterol in the US are too high and should be lowered,” while others, such as cardiologist Michael Oliver of Imperial College in London, argued “that it was unscientific to equate the effects of a drug with the effects of a diet” (Taubes). At the end of the conference, it was concluded that low-fat diets will have a significant impact on our health by protecting us against coronary heart disease.
Can Dietary Fats Have a Negative Impact on Cholesterol and Weight?
Some researchers tried to relate fats to losing weight. In other words, Wallet Willett, a professor of epidemiology and nutrition at Harvard, said, “low-fat diets are the requisite route to weight loss…and this was held almost to be a religious truth” (Taubes). However, later studies showed that people initially lose weight, but then the weight returns. For example, a study conducted by Women’s Health Initiative (WHI) finds that half of fifty thousand women who were enrolled in this study have been “extensively counseled to consume only 20% of their calories from fat. After 3 years…the women had lost, on average, a kilogram each” (Taubes). Even though it was true that low-fat diets did allow individuals to lose weight like any other diet, the lost weight did return over time. I think this demonstrates the “wishful science” described by Sir Francis Bacon, an English philosopher and statesman, who believed that there are two types of science, “wishful science” and “good science” (Taubes). Wishful science is the one that is without evidence and starts to “go downhill” over the time while “good science” is the one that develops and becomes more compelling over the time (Taubes). Our society wants to solve the issue of obesity that is causing some health consequences. I think blaming saturated fats is an easy way to solve the issue.
Since cholesterol was predicted to have some relation to dietary fat, researchers were interested in studying it more. Researchers heavily studied two types of cholesterols: LDL and HDL. LDL, low-density lipoprotein, is the “bad” cholesterol that delivers fat and cholesterol from the liver to tissues that need it. However, this can lead to atherosclerotic plaques. On the other hand, HDL, high-density lipoproteins, are the “good” cholesterol that return cholesterol to the liver. If HDL is high, then the chances of developing a heart disease would be low.
By the late 1970s, HDL was officially accepted to have some benefits. However, they concluded that saturated fats “cannot be quite so evil because, while they elevate LDL, which is bad, they also elevate HDL, which is good” (Taubes). Furthermore, some saturated fats contain stearic acid, like in chocolate, which raises HDL levels but has no negative effect on LDL. In other words, just like how there are some fatty acids that raise LDL, there are other kinds that lower HDL.
Is the Threat of Saturated Fats Global?
In 1986 after NIH launched the National Cholesterol Education Program “advising low-fat diets for everyone over 2 years old,” David Jacobs, an epidemiologist from the University of Minnesota, visited Japan and learned that doctors there advise their patients to raise their cholesterol levels since low levels of cholesterols could lead to hemorrhagic stroke and cause a premature death: “Japanese men were dying from stroke almost as frequently as American men were succumbing to heart disease” (Taubes). I think this shows how low saturated fats is seen as the solution for increasing human lifespan in the US but not in other countries. More importantly, it shows how the type of food that we eat and the environment that we live in really affects our health in different ways. This shows that while low-fat diets might help prevent heart disease, they might also raise the chances for other conditions to develop.
The Influence of Sugar Companies on Saturated Fat Studies
A 2016 article argued that “the sugar industry paid scientists in the 1960s to play down the link between sugar and heart disease and promote saturated fat as the culprit instead” based on some historical documents that were previously released (O’connor). In 1967, The Sugar Research Foundation paid three Harvard scientists to publish a study that minimized the link between heart disease and sugar and blamed saturated fats. In other words, I think the sugar industry blamed fats for causing health diseases to promote selling its products, and according to Stanton Glantz, a professor of medicine at U.C.S.F and an author of the JAMA Internal Medicine paper, this derailed the discussion about sugar for decades.
Today, reports still show that several food industries still influence nutrition science. For example, in 2015, a New York Times article revealed that Coca-Cola company has paid millions of dollars to “fund researchers who sought to play down the link between sugary drinks and obesity” (O’connor). I think prominent food and drink companies tend to pay scientists who graduated from prestigious universities to make the results more compelling. This may have caused many Americans to consume low-fat, high sugar diet and increase the chances for obesity. Also, this makes me think that researchers should always be supported by public funding rather than industry funding to prevent biases in the results.
Saturated Fats and Mitochondrial Dysfunction
In today’s society, some Americans believe that high saturated fats intake and obesity can increase the risk of heart failure and arrhythmias. In addition, some human epidemiology studies believe that the risk of having a sudden cardiac death is increased in patients who have high saturated fat intake. In this case, saturated fats could be more harmful to the heart than obesity per se. For example, a 2015 published research study hypothesized that “physiologic levels of saturated fat could increase mitochondrial reactive oxygen species (ROS) in cardiomyocytes, leading to abnormalities of calcium homeostasis and mitochondrial function” (Joseph). Hypertriglyceridemia is a high level of fats in the blood that can lead to atherosclerosis and “hypothalamic ROS production was required to restrain food intake during hypertriglyceridemia” (Benani). This study used palmitate, which is one of the most common saturated fatty acid found in plants and the bloodstreams of animals, to see the effects of fatty acids on cardiac metabolism.
Scientists made several conclusions based on the results. First, they confirmed that palmitate can cause mitochondrial calcium overload in cardiomyocytes by increasing calcium leak from the sarcoplasmic reticulum or SR. Cardiac mitochondria are connected to the SR and calcium release is taken by the mitochondria. Therefore, it makes sense that abnormal calcium release induced by palmitate would cause mitochondrial dysfunction in cardiomyocytes. Second, they learned that “PKC activation was necessary for palmitate-induced ROS generation,” therefore, by using “PKC inhibitors prevented the decrease in mitochondrial inner membrane potential and mitochondrial calcium overload induced by palmitate” (Joseph). Third, they observed that NOX2 inhibitor peptide prevented mitochondrial dysfunction by preventing calcium overload. Finally, low levels of NOX activity can be beneficial to our body by generating ROS as a signaling intermediate, but also can be harmful when its activity is increased in human heart failure. As a conclusion, high amounts of saturated fats, such as palmitate, can lead to chronic activation of NOX2, which can promote heart failure and arrhythmia.
Overall, scientists concluded that PKC and NOX2 were required to allow for palmitate-induced mitochondrial dysfunction. In other words, even though palmitate “is a normal part of the human diet, yet there is strong evidence that it can cause multiple abnormalities. High doses of palmitate can induce apoptosis in vitro” (Joseph). Even though high activation of NOX2 can promote heart failure, scientists believe that NOX2 inhibition can be used as a treatment for heart failure and potential therapy for heart rhythm abnormalities in diabetic patients.
No More Fats! What Would Happen?
If saturated fats are directly affecting our health negatively, then there must be calorie trade-off. When scientists were encouraging the idea of low-fat diets, they were hoping for Americans to start eating vegetables and fruits more but that did not happen. Marion Nestle, the Paulette Goddard Professor of Nutrition, Food Studies, and Public Health at New York University, said “the great bulk of the $30-billion-plus spent yearly on food advertising goes to selling carbohydrates in the guise of fast food, sodas, snacks, and candy bars. Carbohydrates are all too often what Americans eat” (Taubes). In other words, when Americans consume low-fat diets but high carbohydrates, it can raise triglyceride levels and cause “insulin resistance,” which means that the high carbohydrates replacing saturated fats can lead to several diseases, such as heart disease risk.
What’s the Future of Trans Fats?
In 2003, the Food and Drug Administration (FDA) required that trans fats be included on food labels after they found the evidence compelling enough. As a response, many manufacturers eliminated trans fats in their products entirely. Then, cities including NYC banned the use of trans fats in their restaurants: “By 2012 approximately 75 percent of trans fats had been removed from the U.S. food supply. Blood cholesterol levels responded nationally, just as expected” (Willett). In 2015, the FDA gave food industries only three years to eliminate artificial trans fats from the food supply. In other words, the decision of getting rid of food of trans fats by 2018 can prevent around “20,000 heart attacks and 7,000 deaths from heart disease each year” (Willett). However, food industries reported that they will seek permission to keep small amounts of trans fats in some products. Every day, scientists are learning more about our complicated human body and working to find solutions for some of our health diseases. The science of trans fats is still developing and in the future, scientists could find results that would disagree with the 2015 mitochondrial reactive oxygen species study.
I do not think there is one perfect diet that works for every single person on this planet. In my opinion, the best diet is the one that keeps us healthy and gives us the best possible intake of nutrients that our body needs. I believe that obtaining a limited amount of dietary fats could be more beneficial than harmful. All dietary decisions can have some consequences associated with them-it is up to us to decide which risk is worth taking.
Benani, A, et al. “Role for Mitochondrial Reactive Oxygen Species in Brain Lipid
Sensing: Redox Regulation of Food Intake.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, Jan. 2007, www.ncbi.nlm.nih.gov/pubmed/17192477.
Joseph, L C, et al. “Inhibition of NAPDH Oxidase 2 (NOX2) Prevents Oxidative Stress
and Mitochondrial Abnormalities Caused by Saturated Fat in Cardiomyocytes.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, 12 Jan. 2016, www.ncbi.nlm.nih.gov/pubmed/26756466.
O’connor, Anahad. “How the Sugar Industry Shifted Blame to Fat.” The New York Times,
The New York Times, 12 Sept. 2016, www.nytimes.com/2016/09/13/well/eat/how-the-sugar-industry-shifted-blame-to-fat.html.
Taubes, Gary. “The Soft Science of Dietary Fat.” The Soft Science of Dietary Fat, 30
Willett, Walter. “The Scientific Case for Banning Trans Fats.” Scientific American, 1 Mar.