Added fructose in foods is worse than other sugars in driving
10 February 2015
Eating foods with added fructose-containing sugars results in
higher risk of suffering from diabetes and cardiovascular disease
according to a study published in Mayo Clinic Proceedings.
The researchers challenge current American dietary guidelines
that allow up to 25% of total daily calories as added sugars, and
propose drastic reductions in the amount of added sugar, and
especially added fructose, people consume.
Worldwide, approximately one in ten adults has type 2 diabetes,
with the number of individuals afflicted by the disease across the
globe more than doubling from 153 million in 1980 to 347 million in
2008. In the United States, 29 million adults (one in eleven) have
type 2 diabetes and another 86 million (more than one in three) have
“At current levels, added-sugar consumption, and added-fructose
consumption in particular, are fuelling a worsening epidemic of type
2 diabetes,” said lead author James J. DiNicolantonio, PharmD, a
cardiovascular research scientist at Saint Luke’s Mid America Heart
Institute, Kansas City, MO. “Approximately 40% of US adults already
have some degree of insulin resistance with projections that nearly
the same percentage will eventually develop frank diabetes.”
The net result of excess consumption of added fructose is
derangement of both overall metabolism and global insulin resistance
say the authors. Other dietary sugars not containing fructose seem
to be less detrimental in these respects. Indeed, several clinical
trials have shown that compared to glucose or starch, isocaloric
exchange with fructose or sucrose leads to increases in fasting
insulin, fasting glucose, and the insulin/glucose responses to a
“This suggests that sucrose — in particular the fructose
component — is more harmful compared to other carbohydrates,” added
Dr. DiNicolantonio. Dr DiNicolantonio and his co-authors, James H
O'Keefe, MD, Saint Luke’s Mid America Heart Institute, Kansas City,
MO, and Sean Lucan MD, a family physician at Montefiore Medical
Center, Albert Einstein College of Medicine, Bronx, NY, examined
animal experiments and human studies to come to their conclusions.
Data from recent trials suggest that replacing glucose-only
starch with fructose-containing table sugar (sucrose) results in
significant adverse metabolic effects. Adverse effects are broader
with increasing baseline insulin resistance and more profound with
greater proportions of added fructose in the diet.
The totality of the evidence is compelling to suggest that added
sugar, and especially added fructose (usually in the form of
high-fructose corn syrup and table sugar), are a serious and growing
public health problem, according to the authors.
Patrick J Skerrett, Executive Editor, Harvard Health, wrote in
the Harvard Health Blog in 2011: "Virtually every cell in the body
can use glucose for energy. In contrast, only liver cells break down
fructose. What happens to fructose inside liver cells is
complicated. One of the end products is triglyceride, a form of fat.
Uric acid and free radicals are also formed. ... Triglycerides can
build up in liver cells and damage liver function. Triglycerides
released into the bloodstream can contribute to the growth of
fat-filled plaque inside artery walls. Free radicals (also called
reactive oxygen species) can damage cell structures, enzymes, and
even genes. Uric acid can turn off production of nitric oxide, a
substance that helps protect artery walls from damage. Another
effect of high fructose intake is insulin resistance, a precursor to
The 2010 Dietary Guidelines for Americans say it is acceptable
for some people to consume up to 19% of calories from added sugars,
and the Institute of Medicine permits up to 25% of total calories
from added sugars. In contrast, the World Health Organization
recommends that added sugars should make up no more than 10% of an
entire day’s caloric intake, with a proposal to lower this level to
5% or less for optimal health.
Such levels would be more in line with what the authors would
recommend and similarly restrictive to existing American Heart
Association (AHA) recommendations — to consume no more than six
teaspoons (24 grams) of sugar per day for women and no more than
nine teaspoons (36 grams) of sugar per day for men.
While fructose is found naturally in some whole foods like fruits
and vegetables, consuming these foods poses no problem for human
health. Indeed, consuming fruits and vegetables is likely protective
against diabetes and broader cardiometabolic dysfunction, explained
DiNicolantonio and colleagues.
The authors propose that dietary guidelines should be modified to
encourage individuals to replace processed foods, laden with added
sugars and fructose, with whole foods like fruits and vegetables.
“Most existing guidelines fall short of this mark at the potential
cost of worsening rates of diabetes and related cardiovascular and
other consequences,” they wrote.
The authors also think there should be incentives for industry to
add less sugars, especially fructose-containing varieties, to
food-and-beverage products. And they conclude that at “an individual
level, limiting consumption of foods and beverages that contain
added sugars, particularly added fructose, may be one of the single
most effective strategies for ensuring one’s robust future health.”
DiNicolantonio et al. Added fructose: a principal driver of
type 2 diabetes and its consequences. Published online in advance of
Mayo Clinic Proceedings, Volume 90, Issue 3 (March 2015).