Recently, a reader forwarded me a link to a book about a diet that supposedly would cure type 2 diabetes. “My mom is a type 2 diabetic,” she wrote, “but I find it hard to believe that you can reverse it.” So, is this book for real? Can type 2 diabetes really be reversed with a diet? I take a closer look in this week’s show.
Q. Makers of coconut sugar claim that it has a low glycemic index and is high in potassium and some other minerals. Would using coconut sugar make my cookies the healthiest on the block?
A. Replacing cane sugar with coconut sugar might make your cookies a little higher in potassium. And to the extent that coconut sugar has a lower glycemic index than regular sugar, the cookies might not cause quite as high a bump in blood sugar–although I’m sure it would still be significant.
But here’s the thing: The fact that coconut sugar has a lower glycemic index is a tip-off that it has a high fructose ratio. (Same is true of agave nectar.) There’s been a lot of buzz about fructose lately: how fructose doesn’t stimulate the release of hormones that signal satiety or fullness, leading to over-consumption and how over-consumption of fructose triggers fat storage or even liver damage. Most of the hysteria, of course, has been focused on high fructose corn syrup. Ironically, high fructose corn syrup is a lot lower in fructose than “healthy” sweeteners like coconut sugar and agave nectar. Continue reading “Is Coconut Sugar a Healthier Choice?”
Given the escalating rhetoric on fructose, I think it’s time to revisit a couple of basic facts and try to regain some perspective.
Fructose is not a toxin. It is not a man-made “chemical.” The fact that is it metabolized in the liver does not mean that it is a poison.
Fructose is a naturally occurring mono-saccharide (sugar) found in fruits, vegetables, nuts, grains, eggs, dairy products and other whole foods. It has been part of the human diet since the beginning. Presumably, our bodies are well-adapted to it. In fact, there might be an evolutionary advantage to the ability to metabolize sugars through multiple pathways–including one that does not lead to an immediate rise in blood sugar.
All nutrients are potentially toxic
As the National Academy of Sciences states: “All nutrients can have adverse effects when intakes are excessive.” That’s why tolerable upper limits (ULs) have been established for many nutrients. The NAS recommends that you don’t exceed 45mg per day of iron, for example. But no-one is suggesting that iron is a poison or that it should be avoided at all costs. Maybe if we had a tolerable upper limit for fructose, we could all relax a little bit.
How much fructose is too much?
According to a recent analysis, Americans are now consuming somewhere between 38 and 73g of fructose a day. A third of that comes from sweetened beverages. The rest comes from other processed foods as well as grains, fruits, vegetables, eggs, cheese, and other whole foods.
It seems clear that current sugar intake is excessive and making us sick. Many argue that it’s fructose, specifically, that’s doing most of the damage. Fine: For the sake of argument, let’s just say that the current average intake of 55g of fructose (or around 10% of total calories) is enough to overload the liver and contribute to obesity and other ills. That suggests that somewhere between 0 and 55g per day is a threshold at which fructose ceases to be a useful (or at least harmless) nutrient and starts to be a problem.
Seeing as it doesn’t seem possible, necessary, or even desirable to reduce fructose consumption to zero, I think it would be useful to start looking for that threshold.
What is the tolerable upper limit for fructose?
If all the high fructose corn syrup on the planet were to disappear tomorrow, you wouldn’t find me shedding a tear. Thanks to government subsidies and a glut of cheap corn, HFCS is produced in massive quantities. As a result, our food supply has been flooded with cheap, empty calories and we’re fatter and sicker as a result.
But I was disappointed by the latest research on HFCS and the way it’s being reported.
In an effort to put the last nail in the HFCS coffin, Princeton researchers have hit the newswires with a sensational research result: Rats fed high fructose corn syrup gain significantly more weight than rats fed sucrose, even when both groups eat the same amount of calories. That sounds pretty damning. But if you read the entire study, I think you’ll be left with a lot more questions than answers.
Weird Science
The authors are making a big deal out of the fact that rats given HFCS gained more weight than rats given sucrose. They don’t mention that they actually had two groups of rats eating HFCS and only one of them gained more weight. The second HFCS group–which ate the same amount of HFCS as the first–gained exactly as much weight as the sucrose group (and, for the record, the same as a fourth group of mice that weren’t given sucrose OR HFCS). You’d think that would deserve a comment.
In a second long-term experiment using female rats, they gave one group chow plus HFCS and another group chow plus sucrose. The sucrose group actually gained slightly more weight than the HFCS group, but the differences were not statistically significant. Seeing as this result directly contradicts (one of) the results from the short-term study, you would think that would have deserved a comment–if not equal billing in the press release.
But in fact, in the part of the paper where they discuss their results, the authors make what appears to be a blatant misstatement. They say that in the long-term experiment, “HFCS caused an increase in body weight greater than that of sucrose in both male and female rats.” In fact, according to their paper, none of the males in the long-term experiment were given sucrose and the females given HFCS gained less weight than the comparable group of females given sucrose. The only females that showed a statistically significant increase in weight gain were a group who were given 24-access to both food and HFCS…a group that had no comparable control in the study.
The Corn Refiner’s Association has raised several questions about study design. But because they are the “bad guys,” no-one seems to take their criticisms seriously. For the record, I am not supported by nor do I support the CRA. (Please re-read the first paragraph of this post).
As I see it, making unhealthy food cheaper doesn’t benefit consumers. The only ones benefiting from HFCS are corn growers and junk food manufacturers. But in a court of law, the rules of evidence are upheld even when we’re all sure that the guy on trial is a bad guy. And the same should apply to research–and journalism.
Weird conclusions
Aside from the problems with the study design and the misleading reporting of the results, the authors also make some odd speculations about the possible mechanisms behind the results (such as they were). For example, the authors suggest that it is the increased percentage of fructose that makes HFCS more damaging than sugar. (HFCS is typically 55% fructose, sugar is 50%). But using their numbers, if we were to replace all the HFCS in today’s typical diet with sucrose, it would reduce the amount of fructose by 3 g per day.Honestly, it’s a little hard to believe that 3 g of fructose a day is responsible for all of our woes. (The 100% increase in refined sugar intake…now that I could buy.)
They also speculate that HFCS might suppress leptin and insulin release, which might fuel over-eating. Yet their own results don’t support this. The rats given HFCS ate the same number of calories as the rats given sucrose–even though they had unlimited access to more food.
Despite the headlines on the press release, the findings on HFCS vs. sucrose are actually so sketchy they’re not even mentioned in the “conclusion” section of the journal article. Ultimately, the only valid conclusion from this study is that if you give rats food and sweetened water, they will get fatter than if you only give them food and water. I think we knew that already.
It’s the quantity not the quality we should be worrying about
Research is research. But in the real world, I think we’ve got our priorities backward. Let’s first focus on reducing the outrageous quantity of sugar being consumed, and then worry about the quality. I’ve said this before (to howls of protest) but I’ll say it again: If you were to reduce your intake of sugar to the levels recommended by the AHA or WHO, I haven’t seen one shred of evidence to suggest that ingesting HFCS (or sucrose) at those levels would lead to obesity or disease.
Note to industry advocates: No fair quoting from this post out of context. At least include a link to the entire post!
I know that many of you are suspicious of nutrition research. Many are convinced that the dairy, egg, beef, corn, or [fill in the blank] industries have bought off the researchers, journals, government, and the media in an effort to cover up the truth about their products–suppressing negative research and fixing studies to produce findings favorable to their products. There are certainly times when research is misconducted, misinterpreted, and/or misreported. That’s why all research (and reporting!) needs to be viewed with a critical eye–and all potential interests need to be disclosed.
Related content: Can we trust industry funded research?
The White Hat Bias
But biases don’t always run in favor of commercial interests. Researchers writing in the International Journal of Obesity have documented what they’re calling a “white-hat bias,” which influences researchers to reach conclusions that support their preconceived notions about nutritional “bad guys.”
As evidence, they present two widely-cited studies on the link between sweetened beverage consumption and obesity. Both studies found that the link between the two was statistically insignificant. Yet these studies are regularly misrepresented by the press and cited by other researchers as evidence that sweetened beverages are positively linked to obesity.
They also show that studies which do find a link between sweetened beverages and obesity are much more likely to be accepted for publication than studies that fail to find a link–a so-called publication bias. In other words, scientists have become so convinced that soda is a “bad guy” in the war on obesity that they overlook or misinterpret evidence to the contrary.
I’m not saying that sweetened beverages aren’t a problem. But ignoring evidence that doesn’t conform to what we’ve decided is “true” isn’t going to improve our understanding. And for those who believe that all nutritional research has been bought and paid for by Big Industry, it’s worth noting that an entrenched “thought bias” can be just as influential (and just as counter-productive) as commercial interests.
It no longer matters whether it’s actually true that high fructose corn syrup (HFCS) is toxic to our livers, full of mercury, or to blame for exploding obesity rates.
The tales that have been told about HFCS have become so pervasive that it’s beginning to hurt sales. Say no more! Manufacturers are now switching back to cane sugar–and using it as a marketing ploy. “Sweetened with real cane sugar!” the packages proclaim.
Sugar is now a healthy ingredient. How Orwellian.
So, what have consumers gained? Well, many feel that products sweetened with sugar taste better. But are they healthier? In my opinion, no.
If we continue to over-consume highly sweetened foods and beverages, we will likely continue to see massive rates of obesity, diabetes, and heart disease. Switching to foods and beverages sweetened with cane sugar rather than high fructose corn syrup is unlikely to have any measurable impact on public health–except perhaps indirectly.
Switching back to sugar will drive the price of these foods and beverages up. Maybe cost pressures will help shrink the ridiculously over-sized package and serving sizes. The only way anyone benefits from eating cane sugar instead of HFCS is by eating less of it.
See also “Scientists see little benefit in scramble to swap processed sweeteners for natural ones” in today’s Chicago Tribune.
I really don’t get it. Fructose is the dietary scapegoat of the decade, blamed for everything from obesity to liver disease. Never mind that most high fructose corn syrup is in actuality no higher in fructose than regular table sugar. Never mind that the increase in fructose consumption (the so-called smoking gun) over the last ten years was accompanied by an equivalent increase in glucose consumption. Never mind that pure fructose is not found in nature or in the normal human diet–it is virtually always consumed in combination with other sugars.
There is so much myth and hysteria circulating about fructose, you would think some solid scientific inquiry would help clarify the situation. But how are we ever going to figure out what part (if any) fructose per se plays in our health problems when researchers continue to design studies that fail to isolate the variables?
For example, this latest study, published in the American Journal of Clinical Nutrition compared a diet that was high in fructose and and also provided a third too many calories with a diet that contained less fructose and the proper number of calories. Those on the “high fructose” diet experienced several unfavorable changes in their blood lipid profiles.
So what? How many of those effects were due to simply overeating? Why not compare two diets with the same number of calories but differing amounts of fructose? And please don’t show me studies that compare diets containing only fructose versus diets containing only glucose because these type of diets don’t occur outside a laboratory.
Is too much sugar to blame for many of our health woes? You bet. Is fructose metabolized differently than glucose and other sugars? For sure. Is fructose poison to our bodies? Fructose is like any other sugar molecule: when refined, concentrated, and consumed in excess quantities, it’s not good for you.
Want to improve your health? Cut down on added sugars–that includes table sugar, HFCS, maple syrup, honey, agave nectar, fruit juice concentrates, and foods made with any of these. You’ll be cutting down on fructose in the process–if that makes you feel better.
But I’ve yet to be convinced that fructose is harmful except in cases where sugar (in general) makes up too large a proportion of calories. In these cases, the effects of fructose on the liver and blood lipids are simply one of the mechanisms by which too much sugar damages human health–no more or less dangerous than any number of other mechanisms, such as the effect of glucose on blood sugar and insulin levels, or the effect of excessive calorie intake on body fat and weight.
A recently published study is going to fuel the hysteria over high-fructose corn syrup. It’s a terrific study. But, contrary to the headlines you are sure to see over the next days and weeks, it does NOT prove that high fructose corn (HFCS) syrup is the cause of the obesity epidemic. Let’s take a closer look.
Researchers at the University of Florida found that rats who were fed a diet that was very high in fructose eventually became resistant to the hormone leptin. Leptin is a hormone that regulates your appetite and disposition toward weight gain. In the second half of the study, they switched the leptin-resistant rats to a high-calorie (high-fat) diet. The rats ate a lot more and gained a lot more weight than rats who had not been on a high-fructose diet. (Read more about the study: “Fructose hampers hormone that controls appetite.“)
Now, what does this tell us about the effects of high-fructose corn syrup on humans? Very little.
Aside from the obvious issue (the study was done in rats, not humans), the study had absolutely nothing to do with high fructose corn syrup. The diet that brought about leptin resistance was about 60% fructose, and contained no other form of sugar. The typical (awful) American diet contains about 35% sugar, about half of which (roughly 17%) is in the form of fructose.
Incidentally, if every bit of HFCS in the food supply was replaced by regular old cane sugar, our fructose intake would still be around 17%. That’s because high fructose corn syrup contains about the same amount of fructose as sugar.
Like the best research studies, this one poses far more questions than it answers. For example, I’m dying to know whether you’d get the same results at 50% fructose. Or 40% or 30%. What’s the threshold at which the effect starts to set in?
Secondly, I’d love to know whether you’d get leptin resistance with similar amounts of glucose or sucrose? In other words, how much of this effect is specific to fructose and how much is just sugar? What’s more significant: the amount of total sugar in the diet or the amount of fructose? How does dietary fat affect things? (In the study, the rats ate an extremely low-fat (5%) diet and the fat was lard.)
I imagine that researchers are queuing up to design studies that will answer these questions and more. (And we’re still only talking about rats…)
Those who read this blog (or listen to my podcast) know that I think the hysteria over high-fructose corn syrup is misplaced. We should be alarmed by the amount of sugar in the American diet and what it is doing to our health. I think it probably is directly connected to our rising rates of obesity, whether through leptin resistance or other means. But I don’t think it’s worth worrying about high-fructose corn syrup, per se, while we’re still getting 35% of our calories as sugar.
This whole thing reminds me a little of people who are freaking out about gas prices and dependency on foreign oil. They’re trading in their cars for models that will improve their gas mileage from 27 to 30 mpg. But it never occurs to them to drive fewer miles.
Here’s what we all agree on
I am sure that large quantities of fructose will cause health problems in rats and humans. I’m pretty sure that large quantities of any form of sugar will do that. Of course, the specific problems that develop will vary depending on what type of sugar you’re over-consuming. Fructose is hard on the liver while glucose is more challenging to the pancreas.
But rather than argue about which form is more dangerous, what about working the problem from the other end of the equation? I”m talking about the “large quantities” part of the sentence.
Eat less sugar and you probably don’t need to worry about HFCS
The World Health Organization recommends that you limit your intake of added sugars to 10% of calories. They’re not talking about sugars that are found naturally in whole foods, like fruit or milk. They’re talking about refined sugars in things like candy, baked goods, soft drinks, and condiments.
For most Americans, this would mean cutting their sugar intake by two-thirds. Whether or not HFCS is really that much worse than other forms of sugar (I’m still not convinced it is), I’m pretty sure that if we simply cut our consumption to a reasonable level, it simply wouldn’t matter.
Call me crazy.