What does bloodletting, scurvy, and our understanding of saturated fat have in common?
Before I share the answer with you, allow me to say that while we live in an era of unparalleled educational opportunities, there are some things that are still undervalued, and often unappreciated.
Skepticism, curiosity, and the ability to think and research for oneself, are not always met with enthusiasm.
Even when there’s concrete evidence to support the view of the minority, popular opinion is not something that likes to go away without a fight.
Take, for example, the advice, “Eat less saturated fat.”
That has been the message from health professionals, like me, for years now.
But, while we have dutifully reduced the percentage of calories we take in from saturated fat over those years, what can’t be ignored is that we continue to have worryingly high rates of obesity, heart disease, and diabetes.
Is it just that people don’t heed the advice, or is there more to it than that?
Learning From History
In 1593, Admiral Sir Richard Hawkins, recorded that orange and lemon juice should be drank as a means of preventing scurvy. In 1614, John Woodall, Surgeon General of the East India Company, published a handbook for apprentice surgeons aboard the company’s ships, which gave similar advice.
And yet, for another 200 years, men aboard ships continued to die due to scurvy, resulting in an estimated 2 million deaths between 1500-1800.
Its eradication from the Royal Navy didn’t come until the 1790′s, when finally, the chairman of the Navy’s Sick and Hurt Board, put the long-ignored prescription of fresh lemons to use during the Napoleonic Wars.
A similar story is seen in the history of bloodletting. A practice which went on for 2,000 years as a cure-all for sickness and disease.
In 1628, William Harvey disproved its widely believed ‘benefits’, and yet, over 200 years later it was still being recommended at the Royal College of Physicians.
Can a similar story be seen in the history of saturated fat? Possibly.
What is beyond doubt, however, is that we’ve become so conditioned to think saturated fat isn’t good for us, that the mere suggestion this may be bad advice makes most people think you’re a quack.
To understand the current popular opinion surrounding saturated fat, it’s important to go back a few years to an important publication by Ancel Keys.
Stick with me. This gets interesting.
How Did The Diet-Heart Hypothesis Originate?
The first scientific indictment of saturated fat came in 1953.
In that year, physiologist, Ancel Keys, published a highly influential paper, “Atherosclerosis, a Problem in Newer Public Health.”
He concluded that while the total death rate in America was declining, the number of deaths due to heart disease were steadily climbing.
He blamed a diet high in fat for these heart disease deaths. This belief is what became known as the diet-heart hypothesis.
And, it wasn’t well received by his peers at the time.
One of the main problems with Keys method was, that although data was available for 22 countries, he only used 6 countries (later 7) in his comparison.
As a result, his research showed an increase in heart disease cases, which corresponded with an increased fat intake.
However, when the 22 countries are included, the data looks more like this:
The second graph shows such a weak correlation, that Keys’ hypothesis is totally demolished.
Statistician, Russell Smith, had this to say about Keys’ research:
“The word “landmark” has often been used… to describe Ancel Keys’ Seven Countries study, commonly cited as proof that the American diet is atherogenic… the dietary assessment methodology was highly inconsistent across cohorts and thoroughly suspect. In addition, careful examination of the death rates and associations between diet and death rates reveal a massive set of inconsistencies and contradictions…
It is almost inconceivable that the Seven Countries study was performed with such scientific abandon. It is also dumbfounding how the NHLBI/AHA alliance ignored such sloppiness in their many “rave reviews” of the study…
In summary, the diet-CHD relationship reported for the Seven Countries study cannot be taken seriously by the objective and critical scientist.”
(Source: Diet, Blood Cholesterol and Coronary Heart Disease: A Critical Review of the Literature, Volume 2, November 1981, pages 4-49)
You may be asking yourself why Keys would leave out such incredibly important data?
The phrase “cherry picking” comes to mind.
This study has, unfortunately, been cited for decades as “fact.”
Brief History Of The Diet-Heart Hypothesis
In the 1950s, Keys and others promoted a low fat diet, which they labeled the Mediterranean diet.
In 1957 the American Heart Association proposed that modifying dietary fat intake would reduce the incidence of coronary heart disease.
In 1961, William Kannel published the landmark paper, “Factors of Risk in the Development of Coronary Heart Disease.” In the following years the term “risk factor” became commonplace.
Also in 1961, the American Heart Association published a report on preventing coronary heart disease, which pointed to reducing certain dietary fats to lower the level of risk.
The report was cautious, however, stating:
It must be emphasized that there is as yet no final proof that heart attacks or strokes will be prevented by such measures.
In fact, they made these recommendations for those who were at risk of cardiovascular disease, either by heredity, or because of a prior heart attack or stroke.
At this time, they were not recommending a low fat diet for all.
According to Daniel Levy, current director of the Framingham Heart Study, the sense of urgency concerning dietary fat and heart disease did not come until 1977.
That year, the U.S. Senate’s Select Committee on Nutrition and Human Needs, put the diet-heart hypothesis on the national agenda when it published, “Dietary Goals in the United States.”
This report stated:
Too much fat, too much sugar or salt, can be and are directly linked to heart disease, cancer, obesity and stroke.
In 1983, a turning point in the obesity/heart disease studies came with the publication of an article based on the Framingham studies. This article cited obesity as an independent risk factor for heart disease.
This was significant because it lent further support to the low fat approach to diet.
Many scientists believed a low fat diet may not only prevent heart disease, but it could also promote weight loss, and as a result, reduce the incidence of obesity.
By 1984, the scientific consensus was that a diet low in fat was appropriate for high-risk patients, but also as a preventive measure for everyone, except infants.
Still Only A Hypothesis
The strange thing in all of this is that the diet-heart hypothesis remained exactly that, a hypothesis.
No studies proved conclusively that saturated fat led to heart disease.
Yet, this notion became ingrained in public health policy, and was widely promoted by health professionals, as if already a proven, indisputable fact.
From 1984 through the 1990s, dietary fat was increasingly blamed for heart disease, as well as for the increasing obesity levels.
Then, when the National Institutes of Health Consensus Development Conference issued, “Lowering Blood Cholesterol to Prevent Heart Disease,” in 1984, it was endorsed by the American Medical Association, and the National Heart, Lung, and Blood Institute.
And, while some scientists and physicians remained skeptical, the argument in favor of the low fat diet for all was the “gold standard” advice, as a result of this report.
The Food Industry
By the 1980s food manufacturers had noticed the profit making opportunities to be had through the low fat diet approach.
They began replacing fat with sugar, which lead to “Snackwell’s phenomenon.” Basically, low fat foods having just as many calories as the former high fat versions.
The result was that people ate more of the low fat food than they otherwise would of the normal cookies, because they believed them to be healthier.
So, in the 1980s and 1990s these low fat, high sugar products began to fill grocery store shelves, in response to consumer demand.
In 1988, in an effort to raise funds and promote better health, the American Heart Association introduced its program to label foods with their “heart healthy” seal of approval.
Food companies were then able to pay for the rights to label their foods with this seal of approval.
Many of these products were packaged foods like breakfast cereals.
One of the main problems was that fresh foods were not labeled, which to some, may have given the impression that these highly processed foods were more heart healthy than fresh foods.
Did all of this mean that as long as a food was low in fat, it could be eaten to appetite?
If so, it’s clear why a diet filled with low fat foods may ironically be promoting obesity, despite its heart healthy seal of approval from the American Heart Association.
Has The Low Fat Diet Been Successful?
Interestingly, from 1950 to 1998 mortality rates from heart disease decreased 53 percent.
However, in 1998, physicians Daniel Levy and Thomas Thom noted a “puzzling paradox.”
While mortality from heart disease had decreased dramatically from 1950 to 1998, the incidence of heart disease remained about the same.
In addition to this, a study covering the years 1987 to 1994 suggested that the reduced mortality rate was the result of medical and/or surgical intervention, and secondary rather than primary prevention.
Unfortunately, these figures do little to clarify the role of the low fat diet in relation to heart health.
(Thanks to Ann Berge and her extensitve report, “How the Ideology of Low Fat Conquered America,” for an overview of the history of saturated fat.)
Saturated Fat: Good Or Bad?
A number of very large, expensive studies have looked at the relationship between heart disease and saturated fat.
In 2000, a respected international group of scientists, called the Cochrane Collaboration, conducted a meta-analysis of the scientific literature on cholesterol-lowering diets.
They included 27 trials, with more than 18,000 participants.
And, although the authors concluded that reducing dietary fat may help reduce heart disease, their published data actually showed no significant effect of a low fat diet on overall mortality, cardiovascular mortality, or cardiovascular events.
Women’s Health Initiative
In 2006, the Women’s Health Initiative (reportedly costing American taxpayers $725 million) found that a diet low in total fat and saturated fat did not significantly impact heart disease risk.
This study followed slightly over 48,800 postmenopausal women for 8 years.
A meta-analysis published in 2010, pooled data from 21 studies, and included almost 348,000 adults.
The researchers found no difference in the risks of heart disease and stroke between those with the lowest and highest intakes of saturated fat.
Reduce Refined Carbs
One of the main problems I have with encouraging a low fat diet, is that you have to replace the fat with something, and that usually means replacing it with carbohydrates, mainly of the refined variety.
A study in 2010, noted that there are few studies to support the notion of replacing saturated fat with carbohydrate.
They concluded the emphasis should be on the limitation of refined carbohydrate intakes, and a reduction in excess weight.
A recent 2011 study, found that dietary intake of saturated fats is associated with a modest increase in serum total cholesterol, but not with cardiovascular disease.
These researchers noted, however, that replacing saturated fats with carbohydrates, particularly those with a high glycemic index, is associated with an increased risk for cardiovascular disease.
Interesting. So removing fat and adding sugar increases the risk of cardiovascular disease?
Can anyone say ‘low fat yogurts’?
But, let’s not just pick on yogurt. Pretty much everything with bold low fat labels, is packed with sugar instead.
Read what Steve Parker, M.D. has to say on saturated fats good or bad.
If you’re not familiar with the term LDL Subfractions, don’t worry. I intend to write about this in a more complete way in the future. However, let me give you a relevant synopsis to add weight to the discussion around saturated fat.
Dr. Krauss, professor of nutritional sciences at the University of California, Berkeley, has been studying the effect of diet and blood lipids (low and high density lipoprotein, commonly referred to as LDL and HDL, and fatty acids) on cardiovascular disease for years.
In 1980, Krauss and his colleagues discovered LDL cholesterol comes in a series of different sizes, known as subfractions. Some LDL subfractions are large and fluffy. Others are small and dense. And, it is this distinction that is important.
While all LDL cholesterol is bad, the small, dense LDL subfractions are really bad, since they greatly increase the risk of developing clogged arteries.
Interestingly, Dr. Krauss found that when people replaced carbohydrates in their diet with fat, whether saturated or unsaturated, the number of small, dense LDL particles decreased.
So, does all of this mean you can eat as much fat as you want?
No, certainly not.
It’s clear there is some association between fat and heart disease. Unfortunately, most studies don’t differentiate between saturated fat and trans fat. I believe this is a big mistake.
Trans fat is known to increase LDL cholesterol levels (as we noted above, LDL cholesterol is bad), while also lowering HDL (good) cholesterol levels.
This is bad news, and the opposite of what we need for good health.
So, if there is one thing you should definitely be avoiding, it’s artificially hydrogenated oils. The trans fats from partially hydrogenated oils are more harmful than naturally occurring oils.
The main culprits to be aware of are margarine, shortening, and partially hydrogenated oils. You will find these in most processed junk foods, and deep fried foods.
At the end of the day, the best way to avoid trans fats is to make sure you are choosing a whole, natural, and minimally processed diet, as much as you possibly can.
The Way Forward
I have struggled with this issue for some time. And, this article is merely a drop in the ocean of all that could be said.
I am well aware that this is information most health professionals won’t be telling you, and until you’ve been through four years of university training in Human Nutrition and Dietetics, you won’t understand how difficult it is to teach something that’s contrary to what you have been taught.
However, something I’ve discovered in recent years is that no one cares how much you know, until they know how much you care.
What good is a degree, if you’re not willing to continually research for the truth, and present that truth no matter how much it goes against the grain?
If the health of our nation is to improve, we need open minded scientists and health professionals who speak truth, and don’t simply regurgitate what they are told to say.
It’s important that we are real with ourselves, and others.
What about you — do your beliefs stand up to the available research on this topic of saturated fats? Please share any interesting studies you know of on this topic with me, too.
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