For most of our evolutionary history, the human diet has consistently relied on a balanced intake of nutrients from both plant and animal sources. Preagricultural humans secured their protein through hunting, which led to an increasing trend in the stature of humans for the foreseeable millennia given the importance of the nutrient in the maintenance and growth of the human musculoskeletal system. Ages passed, and the advent of agriculture as early as 50.000 BC substituted most animal product consumption for plant-based foods, with a dramatic increase to 90% of caloric intake coming from plant-based foods compared to the 50% of the paleolithic era. While the diet of humans of that time significantly reduced need for hunting, and therefore the risks associated with it, their limited consumption of complete aminoacid profiles from animals led to a trend of stature decrease among humans. The protein necessary for a developing body was cut from our diet for millennia, but the industrial revolution of the 18th century reversed this by increasing the accessibility of animal protein. Again, humans returned to their preagricultural pattern of protein consumption, which is reflected in the current statistical trends of human stature. From 1914 to 2014, the average height for men and women has increased by 9 and 8 centimeters, respectively.
While the average human height is increasing, this does not serve as a holistic measure of whether humans are becoming less or more healthy. The historically recent introduction of refined sugar in our diets, often covertly as an invisible ingredient in food products, has skyrocketed the prevalence of diabetes, heart disease, mood disorders, and obesity. An unexamined transition towards plant-based protein consumption can decrease longevity and affect organ health when diversity of protein sources is not considered. Achieving a complete essential aminoacid and micronutrient intake requires a studied diet that combines multiple foods with varying aminoacid profiles. Another macronutrient whose consumption has dramatically changed in the last century is seen in lipid or fat intake. Historically, humans have secured their fat intake from a mixture of animal and plant-based sources. Animal fat typically came from fatty meats and organs, as well as butter or lard used for cooking. Plant-based fat was sourced from avocado, olive, nut and seed consumption, which contain OMEGA-3 fatty acids connected with a myriad of health benefits, including anti-inflammatory, cognitive and mood boosts.
More recently, however, this balanced proportion of caloric intake has been disrupted by the introduction of vegetable and refined seed oils. These oils are found in most products at a grocery store, be it bread, sweets, ice cream, cured meats or plant-based meat replacements. It is necessary to point out that oil extracted from the pulp of the vegetable, as in the case of coconut, olive and avocado oils undergo much less processing and have a different chemical profile from vegetable oil. The latter are usually extracted from the seeds of legumes and are subjected to multiple rounds of processing, involving the addition of chemicals to the oil and repeated exposure to heat. This removes the natural flavors and odors by breaking down the fat molecules of the liquid. To this effect, vegetable oils have allowed for a cheap, accessible means of cooking, while providing a neutral flavor to foods that is sometimes undetectable. Conversely, the history and biology behind vegetable seed oils reveal a more ominous side to this food category that has come to make up between 20-32% of U.S. citizens’ caloric intake in just a century. Perhaps coincidentally, implying correlation rather than causation, the increase of seed oil consumption has been connected to the increase of chronic illnesses among the American population. Currently, 60% of U.S. adults suffer from one chronic illness, while 40% suffer from at least two.
Vegetable oils started being used as cooking oil in 1892, with the introduction of corn oil on the U.S. market. However, this did not compare with the societal impact later products had, such as Crisco. In the early 1900s, soap manufacturer Procter & Gamble, now worth $327.2B, was looking for a replacement for the animal fat necessary to produce soap, and found a cheaper alternative in extracting oil from waste cotton products. After their discovery that this oil could be further processed and solidified through hydrogenation, they came up with Crisco, a solid lard replacement that was declared as a healthy, cheaper alternative to animal fat. At the time, food labels were unregulated, giving the company much leeway in how they could promote their product. What followed was the largest advertisement campaign human history had ever known. Together with the J. Walter Thompson Advertisement Agency, the first of its kind in the U.S., Crisco was able to become a nation-wide sensation. This was due to highly aggressive advertising, such as testing the promotion strategy in 8 different cities before deciding upon a final nation-wide course of action. Free samples were sent to restaurants and grocery stores, while snacks cooked with Crisco were handed out on the streets alongside cookbooks.
The next step in securing the prevalence of Crisco consumption was hosting fundraisers and donating the proceeds to the American Heart Association (AHA). Who better to tell you that a new cooking oil is healthy than doctors and respected researchers? In 1948, the AHA netted the modern equivalent of $18.5M and rose to national renown, heavily promoting consumption of Crisco. Only one year later, Procter and Gamble sponsored one more national fund-raising campaign, this time netting a whopping $33.6M. The AHA received the funds and fame to tell everyone in America that heart disease was the biggest problem in the nation, while Procter & Gamble had a credible platform where they could sell their product as the solution. During this time, the academic consensus was moving towards explaining recent trends of heart disease as the result of saturated fat often found in animal products. This led to the hypothesis that having a lower cholesterol level reduces the risk of developing heart disease. As such, the substitution of lard or butter with seed oils came as a natural result of studies that claimed this relationship was real.
The most ardent proponent of vegetable oil consumption was Ancel Keys, who connected the lower incidence of coronary heart disease during WW2 in Europe with lesser availability of animal fat during the war. Ancel became increasingly popular with his cholesterol hypothesis, becoming a member of the AHA nutrition committee. Only one year later, the now large association communicated a new set of nutritional guidelines to the U.S. population, unsurprisingly promoting the consumption of polyunsaturated fat found in seed oils. In 1970, Keys wanted to cement his position by publishing the Seven Countries study. Designed to confirm his hypothesis, the study collected data from 22 countries to show that countries with less animal fat intake had lower prevalence of heart disease. However, only seven countries were cherry-picked that supported Keys’ statements. For example, the Greek island of Crete was one such location. Keys spent a total of three weeks there collecting data, but that happened to be during Lent, a Greek-Orthodox practice that involves a temporary omission of animal products from one’s diet. As a result, Keys correlated the lack of Greek meat consumption at the time of his observations with lower rates of heart disease that were actually caused by Greek consumption of healthy fats from nuts, fish and olive oil. The study was considered a large success, and methodological critique of the study was dismissed, even with the advent of studies that linked vegetable oils to multiple illnesses.
The 90s marked a shift in academic consensus, with evidence against the health benefits of vegetable oils mounting up. Every 2% long-term increase in trans-fat consumption was estimated to lead to a 23% higher risk of heart disease. At the same time, the Crisco originally sold by Procter and Gamble was revealed to have contained 50% trans fat. More recently, Cristopher Ramsden has pioneered the republication of multiple studies from the 60s and 70s that utilized incomplete data to support the cholesterol hypothesis. For example, the Sydney Diet Heart Study omitted data indicating that saturated animal fats do not increase mortality for fear of being controversial. Conversely, analysis of the entire data revealed that the group which did not consume vegetable oils had less risk of developing chronic illnesses despite containing twice the amount of heavy smokers. Similar results were recorded in the Los Angeles Veterans Administration Study of 1971.
These adverse health results come from the processing of vegetable oils. The repeated heating-up of vegetable oil during processing makes for substances that are prone to oxidation, to the point that the oils oxidize even when stored and unheated, and after consumption while in the human body. This oxidative process releases aldehydes, which are toxic molecules that clog human arteries while impacting mytochondrial function, and can possibly lead to Alzheimer’s Disease after long term consumption. In primate studies, monkies eating a modern diet higher in safflower oil developed extreme depression. Mouse studies have shown that a total susbtitution for the polyunsaturated fats of vegetable oils leads to death within two weeks. Despite these findings of the last decades, vegetable oils remain a consistent element of the modern human diet, with the global availabily of vegetable oil per capita increasing by 250% from 1970 until 2010.
The purpose of this article was to highlight how a clever ad campaign and some ’financial lubrication’ to a respected scientific association has led to a global pattern that is ultimately in disservice of the human population, sacrificing the health of the many for the profit of the few. Cardiovascular diseases, statistically improbable until the introduction of seed oils on the market, now take 18 million lives every year. For comparison, the coronavirus pandemic has taken 6.5 million lives at the time of writing this article. Until action is taken to control or even remove the accessibility of this food category from human diets, the future is uncertain when it comes to our health. Even in the health-conscious Netherlands, extensive consumption of deep fried foods and the addition of seed oils in the oft consumed peanut butter is still prevalent. Therefore, I urge readers of this article to check the ingredients of what they buy for vegetable oils, to consume more olive, avocado, and coconut oil, nuts and fish, and to reconsider the archaic stigmatization of saturated fat.