This is a serious question. Because of the power of the media, we see the bad ones... again and again and again. In health circles, virtually every health circle other than Frugarians, Sugar and Fructose are villanized.
Yet people zealously defend the last bit of fruit in their diet like im suggesting to the pope that god does not exist(which I will gladly do given the chance)
Obviously the opinions of the HFCS producers over at Sweet Surprise should be ignored, but barring them, where are the positive studies, fructose is great for X. Fructose prevents Y. We NEED fructose for Z.
I understand that in very limited quantities, fructose is used preferentially to restore liver glycogen, but after that, it only causes AGE production among other presumed issues.
I say presumed, because every study done is flawed in some way and want to avoid the pure semantic arguments to focus on our health instead.
Snipped the Studies as Irrelevant, Google Fructose Studies if you want to see an epic list of Dangers that have been scientifically shown, regardless of the flaws of the studies.
- VERY IMPORTANT *
I havent read thru all of these studies. II did not post the following 20 pages which contain many many more negative studies and not 1 singular positive one. I have attempted to find any studies that found positive benefits of fructose, yet most of the studies above, even while many are animal, in vitro, or otherwise flawed, are repeated over and over again. No matter where you seem to look, all of the information is negative and scientifically biased AGAINST fructose.
Even HFCS industry, and "Sweet Surprise" is limited to, HFCS is no worse than standard sugar.... With their untold fortunes, even they cannot come up with positives for fructose.
I eat alot of flack for fully speaking up against fructose, so im laying out the gauntlet. Educate me. Educate Us, show us the SCIENCE, not opinion of how fructose is good.
Dont simply try to tear apart all of the bad studies. That only proves that youre good at dissembling studies. Show us SCIENCE where fructose is actually good above a very minimal amount.
I would LOVE to find that larger amounts of fructose are good for me and not going to hurt me in the LONG run. The Science I can find, ALL of the science I can find says otherwise above a very small quantity.
A study showing positives of fruit, does not make FRUCTOSE good either, it simply shows that the other beneficial chemicals, nutrients etc are beneficial, the problem with that argument, is that ALL of those compounds vital for life are available thru non fructose pathways.
Sway us with Science, not just opinion.
Dr. Kurt Harris did a very nice Carb Writeup where he addresses Fructose, just wanted to add a few quotes from it.:
In the case of fructose, we have a monosaccharide that has the same chemical formula and a caloric content equivalent to glucose, but is treated quite differently by the body because it has a different 3- dimensional structure.
2) Because fructose spends more time than glucose in the unstable and reactive open configuration, it can react with proteins in a chemical reaction known as the maillard reaction. This results in glycation ??? attachment of a sugar ??? to other molecules, especially proteins. As proteins can be important structurally or as enzymes, this can have pathologic consequences. These glycated compounds are known as advanced glycosylation end products ??? AGEs.
4) When there is fructose in excess of glucose, or even when there is a large amount of fructose with glucose, there is often malabsorption in the small bowel ??? this can lead to rapid fermentation by bacteria in the colon, or abnormal overgrowth of bacteria in the distal small bowel. I speculate that fructose malabsorption is actually a defense mechanism to keep the liver from being overwhelmed by this metabolic poison, and the fact that we have not evolved a mechanism to handle big-gulp doses of fructose to the small bowel indicates modern quantities are likely outside of our evolutionary experience ??? the EM2.
5) When fructose is absorbed, it goes via the portal vein directly to the liver, and the liver attempts to clear it completely so it cannot get into the general circulation. This is good, as fructose seems to be about 10 times more likely to cause glycation than glucose. Even small amounts of it can wreak havoc.
6) To keep fructose out of the general circulation, it must be immediately burned or stored as fat. Fructose is related to the spectrum of serious diseases known as NAFLD (non-alcoholic liver disease), including fatty liver and cirrhosis.
7) Excess fructose, chiefly via the liver volunteering to ???taking one for the team??? causes a variety of negative effects that are linked to pathologic insulin resistance, metabolic syndrome, a general inflammatory state, and of course obesity.
8) Finally, fructose has no immediate effect on insulin release, but is linked to pathologic hyperinsulinemia via it???s effects on the liver. This is the exact opposite of glucose, which requires insulin to partition it when eaten, but for which there is no good evidence to relate it to chronic pathologic hyperinsulinemia.
(Note: This does not mean eating glucose is harmless once you have metabolic syndrome. You also have to be careful of large boluses of fat once your gallbladder is diseased. This doesn???t mean eating fat caused your gallstones, though - quite the opposite in fact.)
Why do we lump harmless starch and possibly toxic fructose together and say they are equivalent macronutrients? They seem to have very little in common metabolically. Who cares about the paper chemical formula?
How many human diet trials or animal trials have you seen that lump them together? How many that treat them as totally separate variables like they should?
asked byStephen_Aegis (22913)
Get FREE instant access to our Paleo For Beginners Guide & 15 FREE Recipes!
on January 09, 2011
at 01:36 PM
This is all from this recent review in Nutrition and Metabolism. Health implications of fructose consumption: A review of recent data. It seems like a reasonably objective overview of the current scientific evidence and is worth a read as it compares the evidence from animal and human studies. I picked out some possible possitive effects and included the linked articles in the text.
"While some investigators are able to detect deleterious effects with high doses or could not detect with moderate doses, others found beneficial effects. Koivisto et al 113 demonstrated that the substitution of moderate amounts of fructose (45-65 g/day: 20% of carbohydrate calories) for complex carbohydrates for 4 weeks improves insulin sensitivity in type 2 diabetic patients."
"In small doses, however, dietary fructose appears to be beneficial in enhancing glucose tolerance 143,144. The addition of small doses of fructose to a glucose meal can enhance hepatic glucose disposal. Moreover, the addition of small amounts of fructose to orally ingested glucose increases hepatic glycogen synthesis and reduces glycemic responses in subjects with type 2 diabetes 145."
"Recently, a meta-analysis 40 demonstrated that fructose intakes from 0 to ??? 90g/d have a beneficial effect on HbA1c. This meta-analysis was done on a group of studies in healthy, glucose intolerant and type-2 diabetes. The authors, however, are aware that 50 to 100g is a high fructose intake that could affect postprandial triglycerides. Whether a lowering or maintaining of low HbA1c with these doses of fructose would persist is unknown. We could conclude that moderate fructose consumption (<50 g/d, or >10%ME) appears acceptable and potentially beneficial."
It is hard to find benefits from a nutrient that only makes up a small portion of a normal diet and it seems more likely that fructose is neutral at low doses rather than good or bad. I have included the main conclusions here.
"Certainly high fructose consumption can induce insulin resistance, impaired glucose tolerance, hyperinsulinemia, hypertriglyceridemia, and hypertension in animal models. There is no evidence for similar effects in humans at realistic consumption patterns. Although there are existing data on the metabolic and endocrine effects of dietary fructose that suggest that increased consumption of fructose may be detrimental in terms of body weight and adiposity and the metabolic indexes associated with the insulin resistance syndrome, much more research is needed to fully understand the metabolic effect of dietary fructose in humans.
Despite the epidemiological parallel between the marked increase of obesity and fructose consumption, there is no direct evidence linking obesity to the consumption of physiological amounts of fructose in humans (??? 100g/day). A moderate dose (??? 50g/day) of added fructose has no deleterious effect on fasting and postprandial triglycerides, glucose control and insulin resistance. There is no existing evidence for a relation between moderate fructose consumption and hypertension. Fructose may induce hyperuricaemia, but mainly in patients with gout."
To be clear I do not eat a consume much fructose. There is certainly the possibility that high intakes consumed by the average person are not good for long-term health. I don't think fructose itself is "good" simply that at modest consumption it is probably neutral. The debate is really about where you draw the line of what is excess fructose.
Drinking 25% of your calories as fructose in sweetened water is a bad idea. Study Shows More Insulin Resistance With Fructose-Sweetened Beverages
Eating ~1% of your calories as fructose in an orange is fine (You don't have to eat any if you don't want to though).
Just some random cell culture studies I came across:
on February 02, 2011
at 06:42 PM
I must say, Stephen, as a result of self-experimentation and a lot of research, I've come to completely agree with you with regard to fructose. I'm of the opinion now that an individual's fructose intake is almost wholly responsible for their adiposity. This includes "natural" sources of the stuff. The less fructose I ingest, the leaner I get.
Ingesting massive doses of fructose in its monosaccharide form (as one does when they drink a soda) is far worse than if it were the same amount bound in disaccharide molecules. Sucrose is definitely not good for you, but HFCS is a far more potent poison. I suspect that eating large quantities of raw honey results in the same effect, paleo or not. There is a significant quantity of unbound fructose in honey: http://www.thepaleodiet.com/nutritional_tools/fruits_table.html As such, it is my opinion that it should be avoided.
The fact that nearly all ingested natural fructose is shunted to the liver is a problem, but what's worse is overloading your liver's capacity and having the stuff circulate in the bloodstream and glycate proteins throughout the body. This happens every time someone drinks a soda. Some required reading:
on January 09, 2011
at 01:43 AM
Deconstructed food: fashionable in avant-garde restaurants and in scientific experiements, not in what I think should be everyday eating.
This being said, I don't see any problem with asking the question, even "just" for philosophical, intellectual, or whatever, reasons. Downvoting a question might prevent people from asking, and I really think that this communitiy should incourage both questions and critical thinking.
Stephen, probably your recent meta-question about downvoting caused some confusion: - Your suggestion: if you downvote you must provide the explanation for disagreement - Interpretation: if you have an explanation for disagreement you must downvote :)
on January 12, 2011
at 11:26 PM
As long as you take your fructose with fibre (ie get it from whole fruit and not juice) you should be fine.
on January 09, 2011
at 12:25 AM
IMO, fructose consumption in the form of fruit consumption MAY potentially be useful for those who exercise heavily or are trying to or need to put on weight. This situation was probably more common in paleolithic times than it is now. I personally am not totally convinced that lots of fruit is damaging to those who have healthy metabolisms, provided that processed foods and other garbage food is not consumed and especially if reasonable amounts of healthy fats and proteins are also consumed.
FYI, I think it's a great idea to deliberately take the devil's advocate side when looking at an issue and deliberately look to see what people on other camps are saying. This helps keep us honest and lessen the chances we are being myopic and missing important data. So I like this question.
on October 06, 2012
at 01:38 AM
Moderation is the answer to all the dietary requirements of the human body.Too much of every thing is bad,this is true for fructose as well.
on February 02, 2011
at 07:17 PM
i also want to add kurt harris' treatise on carbohydrates to the discussion. his damning of fructose is pretty convincing...
on January 13, 2011
at 12:48 AM
Stephen please note that several of the studies showing negative impact (perhaps all, though I did not read all of them) refer to HFCS "High Fructose Corn Syrup" which is the artificial synthetic sugar added to most beverages: http://www.diabetesincontrol.com/component/content/article/64-feature-writer-article/4486&Itemid=8
HFCS is not really fructose (although it is branded as such) and therefore all of this "science" that you refer to is concerned with a derivative of corn not present in fruits. Again: there is no HFCS in fruits, not at all! HFCS studies are basically irrelevant for your point on fructose, since the only thing in common is the misleading "fructose" word in the HFCS branding. I am not saying that fructose is good, just that the info contained in most of the papers deals with HFCS rather than with actual fructose!
on January 12, 2011
at 11:18 PM
Depends on one's goals. If your goal is to maintain your fat/weight, then adding fruits that are high in fructose could help with that. If your goal is to continue to lose fat/weight, then it seems like a not insubstantial roadblock to one's progress that will eventually become its own stopping point.
The question itself is odd, however, but I suppose it would be useful for a carb-up refeed kind of scenario where someone needs to max out their liver's glycogen stores as you have said. Short of that, it's a good way to increase adiposity without necessarily increasing insulin.