A really well informed and thoughtful comment on my A Sticky Question blog post about the relative evils of sugar vs high fructose corn syrup (HFCS) forced me to revisit this topic one more time (hopefully the lasts time until some new research is done). I wondered if I had missed some important research papers or glossed over some topics. I went to PubMed and did two searches: first for the words sucrose and fructose in the article title, and then for the words high fructose corn syrup in the title. I went through the titles of all papers with these words in the titles (at least anything published after 1995) and pulled out the abstracts of any papers which examined the effects of different sugars on metabolism, weight gain, or health. I found 19 papers that addressed this question and gave them a quick read. At this point, I don’t think my overall conclusion has changed: there really isn’t much evidence to support the claim that HFCS is any worse for you than sugar (sucrose). There was one notable article that showed that rats fed HFCS got fatter than rats fed sucrose, but it was the only article I found that came to that conclusion.
One thing that researches seem to repeatedly question (but not answer) is whether there is a difference between HFCS in overweight individuals or diabetics. This seems like a pretty important question to answer. Again, I’d love to hear from someone if they have evidence to the contrary (specific literature citations would be appreciated, since I’m not finding anything but the one notable example in my PubMed searches). If you want to learn more, I’ve quickly summarized the findings of the 19 papers below – if you’ve heard enough (and I wouldn’t blame you), you’re free to go.
If you’re still here and reading, I guess you want to know more. I hope this summary can serve as a starting point and reference list for anyone else that wants to examine this issue. Below I’ve included the title and link to the text of the abstract (and in many cases, full text) if you want to see if you agree with my summary of their findings.
Literature Reviews or Epidemiological Studies:
This was an extensive review of the existing literature. Short-term and long-term studies showed that consuming fructose (when compared to glucose, not (importantly) sucrose results in increased levels of insulin (hormone that regulates sugar and fat storage), increased levels of leptin (hormone that signals ‘fullness), and increased levels of triacylglycerol (plays role in metabolism). All of these increased levels would suggest that weight gain would be the long term result of the increased levels of these hormones. However, long term studies did not bear out this hypothesis. One thing they noted that could be important is that these increased hormone concentrations could lead to several precursor conditions for diabetes, something that still has yet to be studied. Bottom line: more studies required.
A synthesis of the existing literature was performed to examine the relationship between consumption of HFCS and weight gain. They found little evidence to support the hypothesis that HFCS is responsible for the growing obesity problem. They note that over the last 30 years, while we are consuming more HFCS, we are consuming less sucrose, and that the fructose:glucose ratio in our food has not changed (as HFCS is somewhere from 40:60 to 60:40 fructose:glucose, and sucrose is a disaccharide composted of the monosaccharides fructose and glucose).
This review examined the data to support associatios between HFCS and energy balance – the ration of energy taken in to energy expended. It seems fairly well established the fructose along has a different metabolic profile than sucrose or HFCS, but since HFCS is more similar in composition to sucrose than 100% fructose, there still isn’t much evidence that HFCS has different effects on energy balance and long term health effects than sugar.
Before even reading this article, I examined it’s source – I was a little suspicious since the only author’s last name is White, and it was coming from the White Technical Institute. This ‘Institute’ has no website, and the only information I could find was a business listing for the White Technical Institute that suggests the Institute has only 1 employee. Not a very big institute – so I did some googling, and the main pages associated with the Institute brought me to the Corn Refiners Association ‘Sweet Surprise‘ website. I don’t think I’m going out on a limb to assume that the White Technical Institute is probably solely funded by the Corn Refiners Association, who are not at all neutral parties in this discussion. While this paper’s findings are that there is no difference between HFCS and sucrose, the funding source definitely brings some doubt on the validity and neutrality of the authors.
Another article from our friends at the White Institute…not surprisingly, they conclude that HFCS it not to blame for obesity. Big grain of salt here (even though it doesn’t seem to be going against other research).
These researchers quantified the overall consumption of added sucrose and HFCS in food and beverages in the US. They found that availability and consumption of both HFCS and sugar increase over time from 1965 to 2000, then slightly declined from 2000 to 2004. Over this time HFCS was overtaking sucrose as a sweetener, but it is the overall caloric increase that seems to point the finger at our growing waistlines.
Sugary drinks may promote over-consumption of calories, and HFCS is in sugary drinks. However, they don’t show that there is a difference between sucrose or fructose.
Original Research Articles:
Studies examing the effect of HFCS on appetite:
Rats were allowed to eat however much they wanted of either sucrose, glucose, or fructose, in addition to rat food. Control mice were just fed rat food. Turns out mice that can eat sugar solutions (of any of the three sugars) get really greedy and start eating too much sugar while they are eating less healthy rat food. Conclusions: if mice are given unlimited access to sugar solutions, they will overeat (consumer more calories) than mice given unlimited access to plain-old rat food. Take-away: animals are greedy and will overconsume sugar if allowed – regardless of the type of sugar.
30 Human subjects were fed diet drinks or isocaloric beverages containing sucrose, HFCS, or milk. The subjects were examined to see how satiated they felt after their drink, and then allowed to eat however much of a standard meal of granola and yogurt they wanted to eat. The researchers found that subjects ate a similar amount of the granola meal, no water what drink they were fed beforehand. Bottom line: no change in appetite was found between any of the diet drink, milk, HFCS, or sucrose beverage drink consumers.
Normal weight women were examined for 2 days. On the first day they were fed isocaloric amounts of HFCS or sucrose sweetened beverages. On the second day they were fed normal food, and allowed to eat however much they wanted. The women rated appetite and were sampled for levels fo glucose, insulin, leptin, and ghrelin. Conclusion: There was no difference in appetite or metabolism signals between those fed sucrose or those fed HFCS.
This study examined the effect that carbohydrate sources have on the feeding behavoir of rats. When rats were fed either pure sucrose or pure fructose and then allowed to eat, fructose fed rats ate more protein and lipids, while less carbs. Overall, the fructose or sucrose fed rats ate the same amount of calories.
Studies examining the effect of HFCS on weight gain
Notable Study! This study really stood out from the others as it was a study of rats comparing both the short- and long-term health effects of HFCS and sucrose. Over 8 weeks rates were fed either HFCS and sucrose, and then allowed to eat however much rat food they desired. The control group only was fed rat food. It’s interesting because they did see a difference – the rats with access to HFCS gained more weight that the rats fed sucrose, even though they ate the same amount of rat chow. More interestingly, the HFCS rats ate less HFCS (calories-wise) than the sucrose rats, but still gained more weight. Interestingly, this is the first really conclusive study I’ve seen that HFCS is worse for rats than sucrose.
Researchers here turned some unwitting mice into couch potatoes, feeding them some foods with some combination of trans fats, lard (non trans-fat) HFCS, or normal mice food and limiting the amount of excercise they could do. Unfortunately they didn’t throw sucrose in to the mix, since they found that trans fats made them fatter than lardy mice, and HFCS made them eat more. I wish they had showed run an experiment to see if sucrose made the couch potato rats eat more – right now all I take away from this is that mouse with access to sweets eat more.
Studies examining the effect of HFCS on circulating metabolites and hormones (grelin, leptin, insulin etc)
Rats were fed 1:1 fructose:glucose (similar to but not identical to HFCS), sucrose, or normal rat food. Both the rats fed high levels of 1:1 fructose:glucose and sucrose showed early signs of metabolic syndrome (a syndrome that leads to the increased risk for coronary artery disease, stroke, and type 2 diabetes.) compared to mice fed normal food. Take away message: high levels of any sugar are bad for you.
Human subjects were fed the same amount of calories in either sucrose, HFCS, glucose, or fructose sweetened beverages. Blood samples were collected after 24 and analyzed for a variety of metabolism hormones and related signals, and it was found that the sucrose and HFCS fed subjects didn’t have significantly different profiles. Conclusion: In the short term in human studies, sucrose and HFCS look pretty similar.
Mice were fed diets where their calories either came from starch (control), sucrose, 1:1: fructose:glucose, or 1:1 fructose:starch. This experiment was performed to determine if fructose mediates insulin resistance and glucose intolerance (early signs of diabetes). They did show that fructose is probably the mediator of this, but did not see any difference between the sucrose or fructose:glucose fed mice. This could be important in terms of individuals with diabetes, but more study is required.
Healthy human subjects were fed different amounts of sucrose, fructose, 1:1: glucose:fructose, or carbohydrates in the form of white bread, and examined for glycemic and insulinemic indexes. Glycemic index: Carbohydrates that break down quickly during digestion and release glucose rapidly into the bloodstream have a high GI; carbohydrates that break down more slowly, releasing glucose more gradually into the bloodstream, have a low GI (from wikipedia) The Insulin Index is a measure used to quantify the typical insulin response to various foods. The index is similar to the Glycemic Index and Glycemic Load, but rather than relying on blood glucose levels, the Insulin Index is based upon blood insulin levels (from Wikipedia). Findings: glycemic and insulin index values of glucose fed subjects were the same as those fed white bread, while those fed fructose had lower values. In the end: insulin responses to glucose, sucrose, and fructose were all similar.
Diabetic patients were fed isocaloric diets (for 28 days) of diets high in fructose, high in sucrose, or low in sugar. They observed no difference in glycemic control, serum lipid levels, insulin, or C-peptide (metabolite of pro-insulin). In the end: in the short and middle terms the sugar source doesn’t adversely affect well controlled diabetics.
This article reviewed the existing literature and found that limited data is found comparing HFCS to other sweeteners, and the data suggests that HFCS does not have a different metabolic response than sucrose.