Polyunsaturated Fats: The Real Killer I
They convinced you that vegetable oils were heart-healthy. Did they lie?
What we cover
We reevaluate the potential causes for chronic disease, first assessing the proposed factors that government entities and major medical corporations attribute to the exponentially growing number of individuals who have one or more chronic diseases.
Taking a look at chronic diseases and their causes, sugar—specifically refined sugar and high-fructose corn syrup—are often inaccurately held liable for the rise in chronic diseases. Not only does the research linked here debunk many claims regarding the harmful effects of sugar, but it also shows that refined sugar availability per capita has a statistically inverse relationship with both obesity and the rise in chronic diseases.
Saturated fat is another nutrient widely blamed for the chronic disease epidemic. However, saturated fat has, at best, only a weak correlation with the increase in chronic diseases, while other nutrients like polyunsaturated fat, have a much stronger one.
Sodium is one nutrient often held responsible for causing diseases like hypertension (high blood pressure) and a host of associated diseases, yet there are numerous studies concluding that sodium only contributes to a moderate rise in blood pressure at most. Hypertension is more likely to be caused by another underlying disease, like atherosclerosis, as opposed to excess sodium intake.
Undoubtedly, physical inactivity would contribute to a rise in chronic diseases. However, one study with 20 years of data suggested that leisure-time physical activity in adults has moderately increased from 1997 to 2017.
Given that none of these factors show a significant correlation with the modern-day rise in chronic diseases, there is one key factor that this three-part article series focuses on: the exponential increase of vegetable oils in Western food, and more specifically, polyunsaturated fat (PUFA) intake.
Introduction
Over recent decades, major health organizations and industries have launched a distinctive campaign in an attempt to vilify saturated fat (SFA). Their largely successful efforts to portray saturated fat as a primary contributor to negative health outcomes are evident in advertising, health blogs, official health policies, recommendations, and even federal regulations, where only saturated and trans fats are required to be displayed on nutrition labels. Despite this, some question how the relatively recent movement against saturated fat can be reconciled with its substantial presence in the human diet since the days of hunting and gathering. (Saturated fats and their health implications will be discussed in further detail here.)
In contrast, little attention has been given to a more recent addition to the human diet: polyunsaturated fatty acids (PUFAs), beyond their unearned status as essential fatty acids (EFAs). To clarify, PUFAs have been part of the human diet for as long as saturated fats; however, a distinction arises when considering the exponentially increasing prevalence of PUFAs over the last century. The primary driver of this increased consumption is vegetable oil, a PUFA-dense oil that has developed a booming industry, leading to its pervasive presence in numerous foods sold in grocery stores and restaurants. To address the mysteries surrounding PUFAs, this 3-part series will examine the science of polyunsaturated fats, their correlation with chronic disease, their effects in scientific studies, and provide evidence-backed recommendations for healthier alternatives.
This 3-part series will explore the potential culprits behind chronic disease, differentiate between dietary fats, and examine the science behind polyunsaturated fats and why they are a likely contributor to the ever-prevalent rise in conditions like cardiovascular diseases, cancer, and obesity.
The Search for the Real Culprit Behind Chronic Diseases
The Centers for Disease Control and Prevention (CDC) defines chronic disease as “conditions that last 1 year or more and require ongoing medical attention or limit activities of daily living or both.” Chronic diseases include heart disease, diabetes, and cancer, the most prevalent diseases in the United States and among the most prominent causes of death.[1] Upon examining the data, it becomes evident that chronic diseases have been rising at an unprecedented rate. Misinterpreted national survey statistics on the prevalence of chronic diseases from 1935 to 1936 have led some to believe that the occurrence of these diseases has either remained relatively stable or decreased slightly over the past 90 years. However, a 2011 analysis of the original survey provides a different conclusion: “A closer look at the reports makes it clear that true prolonged illness was defined as three months or more of disability and that only about 45% of those classified as ill in the study actually suffered from chronic disease or disability.”[2] This translates to approximately 7.5% of the U.S. population from 1935 to 1936 having a chronic disease or disability. In a 2024 survey published by the CDC, it was found that about 39% of people in the U.S. are afflicted with at least one chronic disease, 42% have two or more, and 12% have at least five.[3] There are 1.6 times more people with at least five chronic diseases today than there were people with any chronic diseases in 1936. The overall prevalence of chronic diseases increased by 31.5% over 89 years, a period marked by tremendous advancements in medical technology and health advice. Despite significant improvements in medical technology and understanding of the human body, it appears that people are less healthy than ever before. This phenomenon raises the question: what is driving the rise in chronic disease?
Potential Causes of Chronic Disease
It is routinely stated that some of the most significant contributors to chronic disease are sugar consumption, saturated fat consumption, high sodium intake, and physical inactivity. Many people passively accept this dogma, but if chronic disease were increasing while the aforementioned “contributors” were simultaneously decreasing, there would be a substantial logical flaw in the scientific health consensus. To determine if these factors are indeed the health risks that deserve attention, an independent review of the data is warranted.
Is It Sugar?
Sugar is arguably the most demonized perceived threat to public health in recent decades. While smoking, alcohol, and drug abuse are all frequently referenced in discussions of public health threats, none are as broadly applicable as sugar. If one were to be asked what they believe is the primary contributor to the increased prevalence of chronic disease, there is a significant chance that their response will be, without hesitation, “sugar.” With such a massive campaign against sugar and a nearly universal belief that it is contributing to every modern health problem conceivable, one might naturally think that it must be an ever-worsening modern crisis. Despite this, examination of the data proves otherwise: sugar consumption—the data used here specifically, the United States glucose availability per capita from 1970-2021—has not risen in nearly three decades.
Comparing its lowest level in 1970 at 7.8g per day against its peak in 1997 at 12.6g per day, there is a 61.5% increase; from 1997 to 2023, however, the reverse trend is observed: glucose consumption has declined by nearly 27%, as chronic diseases have been simultaneously rising in prevalence.
Furthermore, refined cane and beet sugar has been on a steady decline of consumption from 74.3 grams per day in 1970 to a significantly lower 50.9 grams per day in 2021. This translates to a 31.5% decrease in refined sugar consumption over the past 51 years.
Many might now consider that high fructose corn syrup is the missing factor. On the contrary, the same phenomenon can be observed: while high fructose corn syrup had increased exponentially from 1967 to 1999, its supply has been declining nearly as quickly since 2010, again failing to explain the ever-increasing prevalence of the chronic diseases associated with it.[4]
Is It Saturated Fat?
Behind sugar, saturated fat is perhaps the most commonly cited health threat of the modern diet. According to health consensus, one would expect that an increase in chronic disease should coincide with an increase in SFA consumption. Despite this, the data does not seem to support that expectation: between 1909 and 2010, total SFA consumption has seen only a relatively mild increase, with a steady decrease beginning around 2000.
However, despite SFA increasing by only nine grams over the span of 101 years, polyunsaturated fats have increased approximately four-fold. Note the stark contrast:
Polyunsaturated fats have seen a remarkably steady increase in consumption since 1920, with no indication that this pattern is reversing. It is important to note that this is not necessarily definitive evidence that PUFAs contribute to chronic disease. Even so, it makes a strong case for it by providing a plausible hypothesis, which will be explored further by the evidence presented later in this article.
Is It Sodium?
Eliminating sugar and SFAs as contributors to the rise in chronic disease, there is one more major dietary factor that is frequently blamed: sodium. Sodium differs from the others in that it is typically known only to directly contribute to hypertension; however, hypertension is considered a cause of other chronic diseases such as heart disease and kidney disease.[5] In our article Under Pressure: The Truth About Blood Pressure, it is explained that not only is hypertension not a cause of other diseases, but sodium is also not a cause of hypertension. A 1998 meta-analysis on the effects of sodium restriction on blood pressure found that sodium restriction lowered systolic pressure by an average of only 3.9 mmHg and diastolic pressure by an average of only 1.9 mmHg. The authors concluded: “These results do not support a general recommendation to reduce sodium intake.”[6]
Additionally, a reevaluation of the Framingham Heart Study in 2000—a famous study that originated the current medical guidelines placing stage 2 hypertension at a systolic cutoff value of 140 mmHg—found that “the Framingham data in no way supported the current paradigm to which they gave birth.” Furthermore, the authors later state that “no randomized trial has ever demonstrated any reduction of the risk of either overall or cardiovascular death by reducing systolic blood pressure from our thresholds to below 140 mmHg.”[7] Read our article Under Pressure: The Truth About Blood Pressure for more information on blood pressure and sodium restriction.
Is It Physical Inactivity?
Ruling out dietary factors, a national increase in physical inactivity is often cited as a major contributor to the rise in chronic disease. Physical inactivity has been consistently demonstrated to be a direct contributor to obesity, which, in turn, can lead to the development of numerous diseases. According to survey data on U.S. subjects aged 20 and over collected by the CDC, between 1988 and 1994, 22.9% of respondents reported being obese. By 2015-2016, this number increased substantially to 39.6%, a 16.7% increase over a 22-year period. Linearly, this corresponds to approximately a 0.76% increase per year.[8]
Seemingly contradictory to the obesity statistics, physical activity has seen an increase over time. According to the CDC, “The 2008 federal guidelines recommend that for substantial health benefits, adults perform at least 150 minutes a week of moderate-intensity aerobic physical activity, 75 minutes a week of vigorous-intensity aerobic physical activity, or an equivalent combination of moderate- and vigorous-intensity aerobic activity.”[9]
From 1997 to 2017, those 18 years or older who met these 2008 standards with their leisure-time physical activity had increased from 43% to 51.7%.[9] This indicates that people have exercised more, not less, meaning physical activity is also ruled out as a primary factor driving chronic disease.
How Do These Correlate With Obesity?
As obesity is a significant risk factor for developing numerous other diseases, it is helpful to visualize the rising obesity rates alongside rates of refined sugar consumption and saturated fat consumption. Below is a graph of the relevant compiled data, comparing the percentage change in refined sugar availability per capita, the proportion of saturated fat in the total fat consumed, and the prevalence of obesity:
As observed, saturated fat and refined sugar have been dropping since 1960, while obesity rates have been increasing. Once again, there must be an inherent logical flaw in the modern health consensus that attributes the rise in obesity primarily to sugar and saturated fat. Notably, the spike in obesity rates among individuals aged 20 and older from 1988 to 1999 appears to be inversely proportional to the availability of refined sugar in the United States. Isn’t that intriguing?
It becomes even more interesting—by introducing polyunsaturated fat consumption in the US, this graph is generated:
Comparing saturated fat and polyunsaturated fat alone, it appears that Americans are effectively following modern health recommendations by replacing the saturated fats from sources such as milk, butter, and meats with the so-called ‘heart-healthy’ polyunsaturated fats found in vegetable oils, nuts, seeds, and processed products like margarine and plant-based meat.
It should now be abundantly clear that there is something implicitly wrong with the scientific health consensus. Undeniably, a critical factor is missing; while the specific nature of this factor may be debatable, it cannot be plausibly argued that the current health consensus has identified all major problems.
Therefore, we once again raise the question: what is truly driving the rise in chronic disease? By incorporating a final data point, this graph is produced:
By introducing cottonseed oil production into the graph, it becomes the predominant factor relative to all other data points, nearly obscuring them entirely. For context, cottonseed oil is one of many oils grouped under the umbrella term “vegetable oils.” Cottonseed oil can be easily found in the ingredients of many common household foods, including salad dressings, mayonnaise, store-bought potato chips, and crackers.
Beyond cottonseed oil, other vegetable oils include palm oil, grapeseed oil, and the very common soybean oil. Cottonseed oil serves as a reliable indicator of the market impact of vegetable oils between 1960 and 2011 relative to other data points. If soybean or palm oil were to be included in this graph, fluctuations in the other lines of data would likely become indistinguishable. All these vegetable oils are rich in polyunsaturated fatty acids (PUFAs), which have been discussed in this article, explaining why PUFA intake and vegetable oil production are rising simultaneously.
Upon closer examination of the graph, it is observed that there is a spike in cottonseed oil production around 1976, approximately the same period during which obesity began to increase exponentially. While it would be premature to assert that this is more than a coincidence, the correlation between obesity and vegetable oils will be examined in greater detail in the next article in this series.
The evidence explored in this article effectively supports the hypothesis that the factors commonly believed to cause chronic disease—such as excess sugar intake, saturated fat, excess sodium intake, and physical inactivity—are not the factors driving the ever-increasing rise in chronic disease. While blame is misdirected, a consistent trend of replacing saturated fats with polyunsaturated fatty acids appears to be the only dietary factor with a positive correlation to obesity, a major risk factor for chronic diseases, among refined sugar, saturated fat, sodium, and physical inactivity. As all of these factors decline, chronic disease continues to rise, necessitating a new explanation for this unprecedented modern health crisis.
The studies compiled and discussed in the next article here will explore the effect vegetable oils have on health to help determine whether polyunsaturated fatty acids are contributing to the rise in chronic disease.
Citations
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