Bad Science or Bad Journalism? Top Experts Come Together to Address Nutrition Myths
A group of scientists and public health experts have just released a white paper investigating myths surrounding the Seven Countries Study by Ancel Keys.
Keys was among the first researchers to identify the role of saturated fats in causing heart disease, and was one of the earliest promoters of the health benefits of a Mediterranean-style diet and lifestyle with regular exercise. Many, including his critics, consider him to be one of the most influential nutrition scientists in recent history. Detractors claim that Keys’ research is partially responsible for the low-fat diet trend during the 1980 and 90s, which they claim is the cause of America’s current obesity epidemic.
Why did a team of nutrition experts take the time and effort to revisit this study?
According to the official press release: “Because of the importance of these matters to nutritional epidemiology, dietary guidance, and major public health objectives, the True Health Initiative commissioned a White Paper to examine the historical record and primary source material.”
The paper addresses and investigates the most common myths about the Seven Countries Study, which are repeated in blogs, social media platforms, and mainstream news sites like NBC, CNN, and the Wall Street Journal. It also reports on the strengths and the limitations of the study.
Lead author on the paper was Katherine Pett, MS, MEd, RDN, and the writing group included Joel Kahn, MD, founder of the Kahn Center for Longevity and Clinical Professor of Medicine at Wayne State University School of Medicine; Walter Willett, MD, DrPH, Professor of Epidemiology and Nutrition at the Harvard T.H. Chan School of Public Health; David L. Katz, MD, MPH, director of Yale University’s Prevention Research Center, and founder of the True Health Initiative.
Joel Kahn, MD, one of the authors, notes, “The health of the U.S. and the Western world depends in large part on the quality of diet as identified from scientific studies. There is no room for revision or confusion as lives are at stake, particularly in my field of cardiology.
The thriving cottage industry in revisionist history about Ancel Keys and the Seven Countries Study that underlies some prominent careers and best-selling books may be a product of negligence, ignorance, or even dishonesty. We cannot say which. What we can say, based on primary sources transparent to all, is that the prevailing allegations are false.”
What Was the Seven Countries Study?
The Seven Countries Study was the world’s first multi-country epidemiological study and was also among the first to examine the relationship between diet, lifestyle, risk factors, coronary heart disease, and stroke.
Ancel Keys and his research team collaborated with other scientists in 16 communities around the globe, recording diets, cholesterol, blood pressure, weight, and other stats. Field surveys began in 1957 in the United States, Italy, Greece, Yugoslavia, Finland (Netherlands), and Japan. Repeat surveys were made at 5 and 10 year anniversaries. Three book-length study analyses were published in 1967, 1970 and 1980, along with dozens of other joint publications and articles.
Myths and Controversy
In the recently published white paper, the team of experts addressed four myths and misconceptions about the Seven Countries Study. They looked at the original source material and interviewed researchers involved with the original study.
MYTH 1: Data was “cherry-picked” and countries were selected based on desired outcome.
The most popular myth about the Seven Countries Study is that Ancel Keys chose specific countries that would prove his theory about saturated fat. Critics also claim Keys had access to data from 22 countries but only published the data from 7 countries.
The two graphs below are commonly cited as proof that there was data from 22 countries that Keys “threw out.”
In fact, the graph on the left came from a presentation Keys did in New York in January of 1953. The Seven Countries Study did not start until 1957. Keys did not throw out data from any of the countries—he published the results from all of them.
Reporters with even a superficial knowledge of the actual research done during the Seven Countries Study would probably not have repeated this myth, because it assumes that Keys used data from national statistics, and not from fieldwork.
The actual Seven Countries Study was a massive research operation that involved data collection among scientists worldwide. It spanned decades.
MYTH 2: France was purposely excluded from the study because of the “French paradox.”
This myth is similar to the first myth above claiming that Keys picked specific countries to prove his theory. France was one country that critics claim was purposefully excluded. In reality, France was not excluded. They were invited to participate in the study.
“Countries with willing, capable researchers, interest, and funds were welcome to join. Some countries opted out due to lack of interest or resources; Sweden and Spain declined for these reasons, respectively. Representatives from France had been included and Dr. Jacques Carlotti, a physician from Paris, was part of the pilot study team in Nicotera, Italy. Ultimately, representatives from France decided not to participate, possibly due to lack of desire, lack of funding, or both.” (Page 32, Keys white paper).
A sidenote to this myth is that the “French Paradox” did not yet exist. It was first used in a paper by a French epidemiologist in 1981.
MYTH 3: Data in Greece Was Inaccurate Due to Lent
One of the dietary surveys conducted in Crete took place during Lent.
“First, the SCS researchers were aware some dietary recalls occurred during Lent. Statistical comparisons were done and there were no differences in intake between Lenten and non-Lenten sampling periods. Sampling during Lent, rather than being a researcher oversight, was a purposeful choice. If diet was significantly different during this time, it was important for researchers to capture those data accurately.”
Far from overlooking the problems inherent with collecting dietary data during a time of religious fasting, researchers actively sought to see a difference. In the Greek Orthodox church, adherent practitioners can have between 180-200 annual days of religious fasting, a sum that makes up at least half the year. It would be irresponsible not to include days of ritual fasting in populations with high adherence since this would 40 affect the average dietary intake of people over a calendar year, though adherence does not appear particularly strict in this case.” (Pp 49-30, Keys white paper)
Beyond this, the white paper states that data from Greece was consistent with other independent studies on average nutrient intakes across Greece.
MYTH 4: Sugar was not considered.
“The 1980 SCS monograph, an in-depth analysis of 10-year findings, did examine the association of sucrose and indeed found it to be associated with heart disease. However, the association disappeared when saturated fat was also added into the statistical model, suggesting that sugar was associated with heart disease mostly due to its strong correlation with saturated fat in the diet. In contrast, the association between saturated fat and heart disease persisted after adjusting for sugar, suggesting it to be the primary and more significant factor.” (P 7, Keys white paper)
Why Such Hatred for Keys?
The low-carb diet trend, started by the Atkins diet in 1990s, lives on in revised form in Paleo, Keto, and other high-fat, low-carb diets. Many of these proponents believe sugar, not fat, is the culprit in the American epidemic of obesity, type 2 diabetes, and heart disease.
Some blogs and even mainstream journalists cite the Seven Countries Study as the origin of the low-fat diet trend in America, and Keys as the original proponent of a low-fat diet.
In truth, Keys did not suggest that people eat a low-fat diet. He recommended a Mediterranean dietary pattern that was lower in saturated fat. Hundreds of studies since the Seven Countries Study confirm that a Mediterranean-style dietary pattern lower in animal products and higher in vegetables, fruits, whole grains, and nuts leads to healthier outcomes.
Low-Carb vs. Low-Fat?
Clickable headlines declaring “butter is back” and that it’s time to end the “war on fat” blame Ancel Keys and his research for why Americans are fatter and sicker than ever. The common thread is that since Americans were advised to eat less fat in the dietary government goals in 1977, our rates of chronic diseases skyrocketed.
The truth is that America never went on a low-fat diet.
Using USDA data for food availability adjusted for waste, spoilage, and other loss to estimate consumption, the graph below shows what Americans have really been eating from 1970 – 2010.
Graphic via Geeksta
In 1970, Americans ate 147 grams of fat per day; in 1980, it was 162 grams per day; in 1990, it was 167 grams per day; in 2000, it was 191 grams per day; in 2010, it was 190 grams per day. The trend has been continuously upward.
America never went on a low-fat diet. We are eating more fat, sugar, and calories now than we did in 1970. Americans eat too much of everything (but not enough fruits and vegetables!). Let’s compare the above data with the graph below, which includes the above date range.
Graphic via Vox
It’s Not Fat vs. Sugar
At Blue Zones, we promote a plant-slant diet based on our own research in Blue Zones regions, where populations lived the longest, healthiest lives. It is naturally lower in saturated fat because it is much lower in meat products and processed foods. It also naturally lower in processed sugar and refined grains (white bread, white pasta, etc).
Our research concurs with current nutrition and public health research that obesity and other chronic illnesses are multi-faceted: excess calories, excess intake of animal products, excess intake of refined sugar, physical inactivity, cigarette smoking, and other lifestyle factors all play a role.
It is not fat vs. sugar. It’s your overall dietary pattern and lifestyle that is important.
By Naomi Imatome-Yun, Editor-in-chief
August 9, 2017