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Fructose under fire as study reveals it is more damaging to the liver than glucose

Fructose under fire as study r...
In a new study, a high-fat diet accompanied by high levels of fructose proved damaging to mitochondria in the liver, whereas glucose did not have the same effect
In a new study, a high-fat diet accompanied by high levels of fructose proved damaging to mitochondria in the liver, whereas glucose did not have the same effect
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In a new study, a high-fat diet accompanied by high levels of fructose proved damaging to mitochondria in the liver, whereas glucose did not have the same effect
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In a new study, a high-fat diet accompanied by high levels of fructose proved damaging to mitochondria in the liver, whereas glucose did not have the same effect

Fructose may be more damaging to your health than glucose according to a rigorous new animal study comparing the effect of both sweetening compounds on liver metabolism. The research presents some of the clearest causal evidence to date demonstrating how a high-fructose diet not only disrupts the liver’s ability to metabolize fat but also fundamentally damages its mitochondria.

“This is one of a series of studies that we've been doing concerning what role high fructose in the diet plays in terms of insulin resistance and metabolic syndrome,” explains C. Ronald Kahn, lead author on the study. “Fructose makes the liver accumulate fat. It acts almost like adding more fat to the diet. This contrasts the effect of adding more glucose to the diet, which promotes the liver's ability to burn fat, and therefore actually makes for a healthier metabolism.”

Previous research had identified this discordancy between the metabolic effects of glucose versus fructose on the liver, but exactly what was going on mechanistically was unclear. To home in on the physiological processes at play, the researchers compared the metabolic effects of six different diets in mice, including regular and high-fat diets with either high-fructose or high-glucose additions.

A number of different metabolic markers quickly stood out to the researchers. A high-fat, high-fructose diet increased levels of molecules called acylcarnitines in liver cells. This suggested there were excess fat burning processes occurring in the liver of the animals eating this diet in particular.

Another red flag identified by the researchers in relation to the high-fat, high-fructose diet was low levels of an enzyme called CPT1a. Low levels of this enzyme suggested high-fructose diets seemed to be damaging certain mitochondria responsible for normal fat burning processes. And looking more closely at the mitochondria specifically, the researchers discovered both high-fat and high-fat plus fructose diets were damaging these vital organelles.

“When mitochondria are healthy, they have this nice ovoid shape and crosshatching,” says Kahn. “In the high-fat plus fructose group, these mitochondria are fragmented and they're not able to burn fat as well as the healthy mitochondria. But looking at the high-fat diet plus glucose group, those mitochondria become more normal looking because they are burning fat normally.”

While none of this research goes to suggest high-glucose diets are safe or healthy, it is somewhat clear that despite equal caloric content, these metabolic abnormalities were not detected in high-glucose diets. So essentially, excess calories from a high-fat diet will be burned off more effectively when consumed with glucose instead of fructose. Fructose seems to help the liver not burn fat but synthesize and store it.

“The most important takeaway of this study is that high fructose in the diet is bad,” says Kahn. “It's not bad because it's more calories, but because it has effects on liver metabolism to make it worse at burning fat. As a result, adding fructose to the diet makes the liver store more fat, and this is bad for the liver and bad for whole body metabolism.”

The new research was published in the journal Cell Metabolism.

Source: Joslin Diabetes Center

8 comments
BartyLobethal
Is the danger primarily from high-fructose processed foods (i.e. those with added 'corn syrup' )? What are the implications for dietary guidelines with respect to the consumption of fruit?
BrianK56
Good thing I read this I have been avoiding High fructose for the last 10 years.
buzzclick
One should limit consumption of glucose-fructose sugars in any form as best they can. The foods that contain high fructose corn syrup are many. Do your own research and stay away from HFCS-processed food to limit weight gain and diabetes for example. Just about all fruits and veggies have fructose in them in varying quantities, but it's definitely a better way to consume it.
qyt
"In summary, dietary fructose, but not glucose, supplementation of HFD impairs mitochondrial size, function, and protein acetylation, resulting in decreased fatty acid oxidation and development of metabolic dysregulation." The article may be of interest to those on a high fat diet but does not tell us about those on a regular diet. The article headline should reflct that the results were oy from supplementing a High Fat Diet. Also we should note that high fructose corn syrup has a fructose-glucose ratio that is quite similar to that of honey and is close to that in common sugar - the body receives equal amount of fructose and glucose from sucrose. That is true regardless of the level of "processing". On the other hand, a diet that is high in sugar (whether honey, high-fructose corn syrup, fruit sugar or sucrose) is not a good diet.
Skyler Thomas
BartyLobethol- Looks like they used solutions of glucose and fructose in the study. Needless to say, straight fructose is no analog for fresh whole fruit, which has fibers and enzymes which slow and ease the digestion of their sugars, respectively. The study specifically looks at the sugar’s effects in a high fat diet. This article is a bit vague on these points, which is misleading. The research makes no points against fruit being part of a balanced diet.
c w
Fructose is worse than...??? Oh, would you just¡! Stop eating chemicals. EAT WHOLE FOODS.
ADVENTUREMUFFINffin
Although interesting results, the article desperately needs to clarify the source of the fructose. Is it fruit, or is it a synthetic source of fructose?
qyt
ADVENTUREMUFFINffin Fructose is fructose, no matter where it comes from, just like water, carbon dioxide and sodium chloride (common salt). Fructose from corn, fruit or honey is the same substance.