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Report Documents How The Role of Dietary Sugar in Coronary Heart
Disease Has Been Deliberately Downplayed By Industry
A new article
published online in the September issue of JAMA Internal Medicine
investigates the history of sugar research and cardiovascular
health, bringing to light the influence the sugar industry has had on
the science and public policy. Dietary sugar may be a significant
contributor to obesity and diabetes, but its direct relationship to
cardiovascular health is often less discussed. More often, dietary
fats have been blamed for poor cardiovascular health even though
accumulating evidence suggests that not all dietary fats are
associated with cardiovascular disease (see Epimonitor July 2016 Issue
for discussion of health effects of butter consumption).
However, sugar is thought to affect cholesterol levels and blood
pressure, and diets high in sugar are associated with elevated levels
of plasma triglycerides, a known risk factor for coronary heart
disease (CHD). How is it that, despite its prominent increase in the
American diet, there has not been a focus on the adverse health
effects of dietary sugar?
Investigative Report
Lead author of the JAMA study, Cristin Kearns and colleagues
from the University of California, San Francisco attempt to address
this very question. The UCSF researchers combed through internal
reviews, reports, and correspondence from the Sugar Research
Foundation (SRF), now the Sugar Association, demonstrating that the
SRF strategically influenced research culminating in the publication
of a seminal literature review on the role of sugar and fats on
coronary heart disease that implicated fat, rather than sugar, as the
root cause.
Background
Kearns et al. cite evidence as far back as 1954 that the SRF sought to
increase the amount of sugar consumed by Americans through the
promotion of a low-fat diet. This initiative led to over $5.3 million
(in 2016 dollars) of spending to achieve this goal by swaying the
current science and discussion around sugar and its role in human
health. By the mid-1960s evidence had been mounting that increased
dietary sugar may have adverse health effects, and experts were
beginning to suggest that sugar was as important a cause of CHD as
saturated fat.
Around this time John Hickson, vice president and director of
research for the SRF recommended that the organization fund research
on CHD to identify weaknesses in and refute the research linking
carbohydrates and CHD. In 1965 the SRF hired Frederick Stare
from the Harvard University School of Public Health Nutrition
Department, an expert in the dietary causes of CHD to serve as an ad
hoc member on its scientific advisory board. Stare then oversaw what
would become a highly influential literature review published two
years later in the New England Journal of Medicine, co-authored by two
other Harvard researchers D. Mark Hegsted and Robert McGandy
who were eventually paid nearly $50,000 (in 2016 dollars) for their
efforts.
Weighing the Evidence
According to Kearns et al., the 1967 NEJM review written by Hegsted
and McGandy, entitled “Carbohydrates and Cholesterol Metabolism”, was
a critique of articles, many of which were handpicked by the SRF,
examining the role of sugar in heart disease. Hegsted and McGandy
evaluated the quality of these studies discounting many of the
findings implicating sugar in CHD as being questionable, irrelevant
and potentially biased. The NEJM review also summarized the results
of studies on dietary interventions to prevent CHD but again
discounted those that showed substituting starch, vegetables, or fat
for sugar could improve serum cholesterol and triglyceride levels.
Furthermore, Hegsted and McGandy overemphasized the consistency of
studies that pointed to dietary cholesterol and saturated fat as the
primary cause of CHD despite a lack of mechanistic evidence and
concluded with the recommendation that reducing fat intake was the
best dietary intervention for preventing heart disease.
Lasting Influence
The
overall impact of the the SRF’s NEJM review has been lasting.
Stanton Glantz, a professor of medicine at UCSF and co-author of
the JAMA Internal Medicine paper told the New York Times (NYT) that
“they were able to derail the discussion about sugar for decades”,
calling the decision to publish the results in a prominent journal
“very smart”, in order to have an early influence on the scientific
discussion. Control policies for sugar are just recently being
considered at the international, federal, state, and local levels, but
among them CHD is not consistently identified as a result of added
sugar consumption. This is despite the fact that the CDC lists CHD as
the leading cause of death for males and females in the United States,
responsible for more than 600,000 deaths in 2014.
Role of Industry
Research
Although the industry and non-industry funding of the review authors’
experimental research was disclosed in the 1967 NEJM review, there was
no mention of the SRF funding and influence. While the disclosure of
conflicts of interest in research is much more commonplace today, that
was not necessarily the case decades ago. In a statement to the NYT,
the Sugar Association said that the industry “should have exercised
greater transparency in all of its research activity” but generally
defended the industry-funded research. While this underscores the
debate over the veracity of industry- versus publicly-funded science,
the statement by the Sugar Association also points out that “... it is
not only unfortunate but a disservice that industry-funded research is
branded as tainted”.
However, in a separate commentary in the same issue of JAMA
Internal Medicine Marion Nestle, Professor of Nutrition,
Food Studies, and Public Health at New York University contends that
food companies deliberately manipulate their research, citing recent
examples of Coca-Cola funding research downplaying the role of soda in
obesity and a candy trade association funding research suggesting that
children who eat candy have healthier body weights than those who do
not. For their part, Kearns et al. conclude in their report that
“policymaking committees should consider giving less weight to food
industry-funded studies”.
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