This topic is huge. Far too large to cover thoroughly in one blog post. So, this is Part 1. Here I summarize the latest, comprehensive argument against the current Western diet status quo.
I recently completed reading the best-selling book “The Big Fat Surprise: Why Butter, Meat and Cheese Belong in a Healthy Diet” by Nina Teicholz released in May 2014. Ms Teicholz isn’t linked to any particular food or diet entity and, at this point, she doesn’t appear to be selling anything but her book. She is a self-described early-adopter of the low-fat diet because, like many of us, she educated herself and relied upon the experts to inform the public on what to eat, in what amounts and what to avoid in order to maintain a healthy weight and lower the risk of disease. She is an intellectually curious journalist who started to research the evolution of the low-fat diet when her own anecdotal observations didn’t match what experts were saying. What she wasn’t prepared for was the avalanche of evidence that tore away at nearly every fact we’ve come to believe about dietary health. And this isn’t a op-ed in long form. In total, her footnotes and endnotes take up more pages than the narrative portion of the book. It is a meticulous, in-depth study of published, peer-reviewed epidemiological and clinical diet studies that span more than 100 years.
Her research shows that much of what we all accept as truths about the link between certain foods and obesity and disease are no more than unsubstantiated hypotheses. And, in fact, many epidemiological and clinical studies actually support a diet that is quite different from the one currently recommended by the US government and other well-respected health organizations. I’ll chronicle the highlights of the book here but, first, a few terms need to be defined:
Macronutrients: Amino acids, carbohydrates and fatty acids (commonly known as proteins, sugars and fats, respectively) are the 3 macronutrients that every human needs to grow and survive. Each macronutrient has its own role in every component of the human body and its systems. Every food, from table sugar to broccoli, contains at least one macronutrient. Most foods contain a predominance of one macronutrient and, often, these foods come to be known by the dominant macronutrient. For example, bread is known as a carbohydrate even though it contains small amounts of amino acids and fatty acids as well. The fields of health and nutrition, in the last several decades, have been on a quest to conduct studies to determine the “best” and “worst” foods within each macronutrient category and, more importantly, to determine the best distribution of the three within our diets to maximize health. Namely, should our diets consist mostly of amino acids, carbohydrates, or fatty acids? If so, how much of it do we need and how much less of the other two should we have?
Fatty Acids: There are 3 main types and they are differentiated by their molecular structure:
- Saturated Fat: no double carbon bonds, which makes these molecules more stable. The stability means they don’t spoil as easily and are more stable when heated. These fats are normally solid at room temperature and most come from foods sourced from animals, such as meats, dairy and eggs. However, some plants contain saturated fats, the most common being tropical oils, such as palm and coconut.
- Unsaturated Fats: monounsaturated fat and polyunsaturated fat: Monounsaturated fats have one double carbon bond and are, therefore, less stable than saturated fats but more stable than polyunsaturated fats which have two or more double carbon bonds. Common examples of monounsaturated fats are olive, canola and flaxseed oils. Nearly all other plant-sourced oils are polyunsaturated fats including soybean, corn, safflower, sunflower and grapeseed.
Epidemiological Studies: In the field of nutrition, these are studies that follow a group of people over a certain amount of time and rely on surveys and self-reporting to gather information about lifestyle factors such as what they eat and whether or not they smoke, exercise or drink alcohol. The health of these individuals is also tracked: what diseases do they suffer from; if they died during the study, at what age and what was the cause of death? These studies can be useful in that they can point scientists in the right direction when it comes to setting up a clinical trial. Epidemiological studies can show possible correlations and associations but they cannot prove causation. Because these studies rely on self-reporting and a non-randomized sample with no control group, it is accepted that there is a high margin of error in determining correlations and associations from this type of study alone.
Clinical Studies: These are studies that use the Scientific Method. In order for the study to be sound, the sample must be randomized, there must be a control group and the length of the trial has to be sufficient to be able to effectively show a definite correlation and possible causation.
The evolution of the low-fat/low animal-sourced, high carb/high plant-sourced diet:
- Prior to the Industrial Revolution, the American diet consisted of a high concentration of animal proteins and fats. The fats that were used in cooking and baking were all animal-sourced: cream, butter, lard, pork fat and beef tallow were most common. Poultry was much rarer in the diet than it is today. Reported incidents of heart disease, cancer and diabetes were much lower. The most common cause of death was infectious disease and, as such, people died younger than we do today. No one can say for sure that the common diseases of today didn’t exist then as the records would be unreliable. And, who is to say that they wouldn’t have developed these diseases had they lived as long as we do today? What we do know for sure is that obesity, which is associated with all 3 diseases, was much less common.
- In the first half of the 20th century, smoking became much more prevalent, automation and technological advances meant many manual tasks, both at work and home, were either automated or made less strenuous. These advances also took place in the food industry. Pre-packaged goods such as breads, crackers and cookies were now readily available and the amount of carbohydrates in the average diet was increasing as a result. At the same time, the incidence of heart disease in adult American males was on the rise.
- As we headed into the second half of the century, blood cholesterol and its detrimental effects on blood vessels, particularly in the arteries near the heart, was discovered. The experts believed that this increase in blood cholesterol was causing the continuing rise of male heart disease. The key was determining what was causing the increase in blood cholesterol. Puzzlingly, instead of looking at the new environmental factors – such as smoking, decreased exercise, increased pollution and the introduction of processed foods – as the possible culprits, the magnifying glass was placed squarely on a dietary staple that, for centuries prior, was consumed in large amounts with virtually no record of heart disease. It was believed that animal fats, which contain dietary cholesterol, increased blood cholesterol.
- Over the next several decades, many epidemiological studies were done with varying results. Some showed a correlation between animal fat consumption and heart disease, others did not. Two well-documented studies, one of the Inuit and another in tribal Africa, where both populations consumed almost exclusively food from animal sources, showed a lower incidence of heart disease compared to cultures that consumed almost exclusively food from plant sources. No clinical studies were done at this time.
- Despite the lack of definitive scientific evidence and the fact that presumably adult males and females were consuming the same diet but only males were experiencing a dramatic rise in heart disease, a few charismatic scientists would not let go of the animal fat-heart disease hypothesis. They believed there was a link, they simply hadn’t found a way to prove it yet. They felt that an increase in plant-based foods while decreasing animal-based foods could only be a positive for the population. So what was the harm in doing just that until the science could provide the definitive answer? Eventually they were able to convince the American Heart Association and the federal government.
- Directives were given for every man, woman and child to greatly reduce animal fats and replace them with plant-based fats. Vegetable growers and food manufacturers were all eager to comply. Vegetable cooking oils to replace lard and tallow, margarines to replace butter in households, and tropical oils to replace butter in pre-packaged products – all owe their existence to this unsubstantiated hypothesis.
- A few decades later, a wealthy individual who had suffered a heart attack was convinced that the saturated fat-laden tropical oils in processed foods, fast food fryers and movie theater popcorn was the culprit. He was able to enlist the assistance of the soybean and corn industry to get the word out. Remember when cinemas were banned from using tropical oils to make their popcorn? That was all due to one wealthy individual and the makers of the soybean and corn oils that would replace the palm and coconut oils. Not one epidemiological or clinical study ever linked tropical oils and heart disease.
- With food manufacturers left with no stable saturated fats to use in their processed foods, they had to take their unsaturated fats to the labs to find a way to stabilize them. Hydrogen was added to stabilize the carbon double bonds – the birth of partially hydrogenated oils (also known as trans fats). Studies were finally done years after these substances were being used in nearly all our foods. The results were not good. Hydrogenated oils/trans fats were the next ones to be banned. At least that was a step in the right direction.
- In the meantime, the total amount of dietary fat recommended in our diets keeps getting lowered. When we lower one macronutrient, another has to take its place. Enter the high-carb, low-fat diet. Essentially, we’ve dramatically replaced fats with sugars. Obesity, diabetes and some cancers have continued to rise as our consumption of saturated fats have continued to fall. Or, is it possibly, these conditions have continued to rise as our consumption of plant-based oils specifically, and carbohydrates in general, have continued to increase?
- Finally, in the last 30 years, more clinical studies have been done to test the effects of saturated fats, monounsaturated fats and polyunsaturated fats on the body. Overall, the evidence shows everything we’ve been told is upside down. A diet high in saturated fats from animal-based foods seems to be linked to higher HDL (good) cholesterol and lower rates of obesity, heart disease, blood pressure and diabetes. Monounsaturated fats, such as olive oil, seem to have a neutral effect – they appear to neither raise nor lower risk factors for these conditions. While high consumption of plant-based foods and oils (a near-vegan diet) seems to lower HDL (good) cholesterol, raise the risks of heart disease, obesity and diabetes and, in 2 well-regarded clinical studies, was associated with an alarming increased risk of breast cancer. (In those two studies, the groups of women on the high saturated fat diet had the lowest rates of breast cancer among the 3 test groups.)
- But the nutrition experts and those in the position of making dietary recommendations for our population are not budging. Which is why, I believe, Teicholz and some of the scientists who have conducted these clinical trials are beginning to bring their information directly to us.
- Unfortunately, until the acceptance by those in the nutrition community of this new, overwhelming evidence, our food supply remains laden in unstable polyunsaturated fats and our diets are increasingly dominated by plant-based macronutrients, the bulk of which are carbohydrates.
That’s Part 1. A lot to digest, I know. (No pun intended!) In Part 2, I’ll explore what this new information means in relation to some of the most popular diets. And I’ll share with you how I’m personally taking a whole new look at my diet. To read Part 2, click here.