by Marion Nestle

Currently browsing posts about: HFCS (High Fructose Corn Syrup)

Mar 24 2010

HFCS makes rats fat?

I can hardly believe that Princeton sent out a press release yesterday announcing the results of this rat study.  The press release says: “Rats with access to high-fructose corn syrup gained significantly more weight than those with access to table sugar, even when their overall caloric intake was the same.”

How they came to these conclusions is beyond me. Here’s the original paper.

It has long been known that feeding sugars to rats makes them eat more and gain weight.  But, as summarized in Table 1 in the paper, the researchers did only two experiments that actually compared the effects of HFCS to sucrose on weight gain, and these gave inconsistent results.  Their other experiments compared HFCS to chow alone.

The study is extremely complicated and confusingly described.  As best as I can tell, here’s what they found:

1.  The first study used 10 male rats in each group and observed them for 8 weeks.  At the end of the study, the rats fed chow alone weighed 462 grams.  The rats fed sucrose plus chow weighed 477±9 grams.   The rats fed HFCS plus chow weighed 502±11 grams.   The authors say the difference between 477 and 502 grams is statistically significant.  But these rats were offered the sugars for 12 hours per day.  The rats fed HFCS for 24 hours per day, which should be expected to be fatter, were not.  They weighed less (470 grams) than the rats fed sucrose for 12 hours per day.  So these results are inconsistent.

2.  The second study did not compare rats eating HFCS to rats eating sucrose.  It just looked at the effects of HFCS in groups of 8 male rats.

3.  The third study used female rats (number not given) and observed them for 7 months.  At the end of the study period, female rats fed HFCS plus chow for 12 hours a day weighed 323±9 grams.  Female rats fed sucrose plus chow under the same conditions weighed 333±10 grams.   This result is not statistically significant.

Although the authors say calorie intake was the same, they do not report calories consumed nor do they discuss how they determined  that calorie intake was the same.  This is an important oversight because measuring the caloric intake of lab rats is notoriously difficult to do (they are messy).

So, I’m skeptical.  I don’t think the study produces convincing evidence of a difference between the effects of HFCS and sucrose on the body weight of rats.  I’m afraid I have to agree with the Corn Refiners on this one.

So does HFCS make rats fat?  Sure if you feed them too many calories altogether.  Sucrose will do that too.

NOTE 3/26: see point-by-point response to this post by Bart Hoebel, one of the authors of the study, in the Comments below.

Addition, November 23: Thanks to Jeff Walker, professor of Biology at the University of Southern Maine, Portland, for doing a detailed critique of the study, most thoughtful and well worth a look.

Jan 25 2010

A quick Q and A: sugars and fats

I wish I could answer all of the questions that come into Feedback or Comments, but I cannot except occasionally.  It’s a rainy day in New York and today seems to be one of those occasions.

Q: Does the caloric value of a food change when it’s cooked?  In his latest book, “Catching Fire: How Cooking Made us Human,” Harvard Primatologist Richard Wrangham argues that cooking foods changes the available nutrient content and actually raises the available calories.

A:  The rules of physical chemistry tell us that matter cannot be destroyed or created so the number of calories available in a food does not change with temperature.  What can change is our ability to use (digest, absorb) the calories that are there as well as our desire to eat the foods.  Cooking makes the calories in potato starch more available, for example, but has hardly any effect on the calories in meat.  Both, in my opinion at least, taste better cooked.    But cooked or not, the calorie differences will be small and unlikely to account significantly for weight change.

The nutrient situation is also complicated.  Cooking destroys some nutrients (vitamin C is a good example) but makes others more available (beta-carotene).  This is another reason why nutritionists are always advising variety in food intake.  Variety applies to cooked and raw, as well.

Q.  Can you please explain what benefits, if any, there are in using a “natural” sweetener, e.g. agave, over regular sugar?  Are there any differences in terms of glucose/fructose makeup?

A.  Agave is more expensive so you probably won’t use as much of it.  Beyond that, it is higher in fructose than table sugar or honey.  This is because agave contains inulin, a polymer of fructose, which must be hydrolyzed (broken down by heat or enzymes) to fructose to make the sweetener.  It’s a processed sweetener requiring one hydrolysis step, requiring more processing than honey and less than high fructose corn syrup.  It has the same number of calories as any other sugar, about 4 per gram or 16 per teaspoon.

Q.  Also, you’ve written on a prior blog that fructose is “preferentially” metabolized into fat by the body.  Can you explain in more detail what that means?

A.  More and more evidence suggests that high amounts of fructose in the diet are not good for health.  Fructose occurs naturally in fruit and nobody worries about that because fruits don’t contain all that much and the sugar is accompanies by vitamins, minerals, and fiber that are well worth eating.  Honey, table sugar, and high fructose corn syrup (a misnomer) are about 50% each glucose and fructose.  Glucose and fructose are metabolized differently and some investigators believe that excessive amounts of fructose stress metabolism in ways that encourage fat deposition.  Eating a lot of sugars of any kind is not a great idea, which is why there are so many concerns about soft drinks these days.

Q.  I would appreciate some comments about the “Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease.

A.  The study concludes:  

A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD [coronary heart disease] or CVD [cardiovascular disease]. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat.

This is a review of previous epidemiological studies (not clinical trials).  These fail to find a correlation between consumption of saturated fat and heart disease.  This could be because there is no correlation or there is one but they can’t find it.  My interpretation: even if there is one, it is likely to be small.

I am increasingly convinced that studies of single nutrients – sugar, fructose, saturated fat, or even omega-3s – will give complicated results when removed from their dietary context.  People who eat foods containing a lot of sugars or animal fats eat and behave differently than people who do not, but not so differently that health differences will show up in the kinds of studies scientists are currently able to do.

Keep in mind: nutrition science is exceedingly difficult to do because there are so many factors in foods that affect health and so many behavioral, economic, and social factors that affect what people eat.

All of this is why I find nutrition so interesting but I can understand why others might find it frustrating.

Aug 21 2009

Colbert Report: The sugar crisis!

Colbert Report, August 19: I was interviewed on the Colbert Report about sugar policy, of all things.  U.S. sugar policy is so absurd that I did not think it could be satirized, but Colbert managed just fine.  Here’s what I would have said if I hadn’t been completely disconcerted by his dousing himself with five pounds of sugar:

The sugar “crisis”: On August 5, several groups representing makers of processed foods wrote a letter asking the USDA to raise the quota on imported sugar because stocks are lower than they have been in years.  Why?  Because domestic sugar production is thoroughly governed by quotas, imported sugar is thoroughly controlled by quotas and tariffs, and high fructose corn syrup (HFCS) is increasingly diverted to ethanol.  Got that?

Reminder about definitions: “Sugar” usually refers just to sucrose made from sugar cane and sugar beets; it is glucose and fructose stuck together.  The other major sweetener is high fructose corn syrup (HFCS).  It is also made of glucose and fructose, but separated.   Sucrose and HFCS work the same way in the body and are hardly distinguishable physiologically.   For the purposes of this discussion, I use sugar to refer to the sweetener refined from sugar beets and sugar cane, and HFCS for the sweetener made from corn.

Sugar protection policies: Even though it amounts to only 1% of agricultural production, U.S. sugar is the single most heavily protected agricultural commodity.  No matter what the price on the world market, U.S. sugar producers and processors get paid a high price.  Historically, this price has been two to three times higher than world market prices.   Although this has for decades cost American consumers $2 billion to $3 billion a year in higher sugar prices, nobody much noticed because it “only” amounted to about $10 per year per person over and above what you would pay for sugar anyway.  Today, the gap between domestic and world market prices has gotten much smaller, mainly because there isn’t as much HFCS around (more on this later).

Quotas and tariffs: These are amazing, really.  U.S. producers are allowed to grow a certain amount of cane and beets each year for which they are guaranteed a price set by USDA.    Beets get 55% of the total quota allotment and cane gets 45%. This works like a closed shop.  If you want to start growing beets or cane for domestic sugar production, too bad.  Catch 22: You only get to have a quota if you already have a quota.  As for tariffs:  The 2008 Farm Bill says that 85% of total sugar in the U.S. must be produced domestically, and only 15% can be imported.  That 15% comes in through quotas distributed among about 20 countries.   Any other sugar they want to send us is subject to high tariffs, except from Mexico.  Under NAFTA, Mexico can export as much sugar to us as it wants to at the favored price.  But imported sugar is never supposed to exceed 15%.

International issues: Our agreement with the World Trade Organization (Uruguay Round) says we have to take a certain amount of world market sugar.  But the 2008 Farm Bill restricts imports.  Oops.  The contradictions in these policies still have to be resolved.  The processed food people think the USDA can raise the percentage.  Can it?  Hmmm.  We don’t know this yet.

Who benefits: A few thousand beet producers in about 15 states and a few hundred cane producers, and the sugar processors.  They get paid amounts that are higher than world market prices.   The countries that have sugar quotas also get higher prices for their sugar quotas.  Producers of sugar cane and beets love this system.   Florida cane producers defend it this way: “U.S. sugar policy ensures that jobs in rural America are not sent overseas, and that American consumers are not held captive by unreliable foreign suppliers of subsidized sugar.”  Like American-owned sugar plantations in the Dominican Republic, for example?

Who loses: According to the Government Accountability Office, everyone in America pays higher prices for sugar than we need to.  This amounts to a transfer of wealth from 350 million of us to a few thousand sugar producers and processors.   International sugar-producing countries that do not have quotas, those in Africa, for example, are also out of luck.

How this happened: The system started out in the Great Depression with the best of intentions.  Despite endless attempts to get rid of sugar supports and let prices fluctuate according to the world market, Congress continues this elaborate and expensive system to protect sugar producers and processors.  These groups have banded together in cooperatives so they avoid anti-trust laws.   Even the New York Times thinks we should get rid of sugar protections.  These groups, of course, are among the most generous and powerful contributors to congressional election campaigns.  Even more, they are equal opportunity contributors: they give to both Democrats and Republicans.  The Fanjul family in Florida is especially influential.  In the best known example, Mr. Fanjul was able to get President Bill Clinton to take his call on a federal holiday when Clinton was in the midst of a tryst with Monica Lewinsky (source: the Starr report).

What about HFCS: The public now puts HFCS in the same category as trans fats: poison (it’s not; it’s just sugars).   In response, makers of processed foods and beverages are starting to replace it with cane and beet sugar.   As explained in the current Advertising Age, sugar is now at war with HFCS.  HFCS used to be a lot cheaper than sugar, but its cost has gone up as more of it is used for ethanol.  Supply is down; costs are up.

Other issues: As if all this wasn’t complicated enough, sugar beets are largely genetically modified, leading more than 70 companies to say they won’t use that sugar.  Sugar cane production in the Southern states pollutes the Everglades, leading to billions of dollars in clean up costs.  And the labor practices of sugar cane plantations have long been the subject of much investigative reporting.  And what about relations with Cuba?  Until the Castro revolution, we got nearly all of our imported sugar from our Caribbean neighbor.  If relations with Cuba improve, will that country have a quota?

So what’s really going on? Food processors want cheap ingredients.   Cheap sugar makes for relatively cheap junk foods and high profits for manufacturers.  Current sugar policies make no sense in today’s global marketplace and we all ought to be eating less sugar anyway.  On average, we have about 70 pounds of sugar and another 70 of HFCS available per year for every man, woman, and child in the country along with a few pounds of other caloric sweeteners to boot.  That’s close to half a pound of sugary calories per day.   Less of all of them would be better, no? 

A final happy thought:  Maybe the processed food makers’ request – which is entirely self-interested – might lead to improvements in U.S. farm policy as well as relations with sugar-producing countries in the Caribbean and Africa.

Jun 8 2009

HFCS-free sales booming

Thanks to Phil Lempert, the Supermarket Guru, for alerting me to the current HFCS-free sales boom.  HFCS, of course, is High Fructose Corn Syrup, the liquid sweetener made from corn (see previous posts).  Food marketers have gotten the message that many people consider HFCS to be the new trans fat, even though it is not much different biologically from common table sugar (sucrose).

HFCS is replaced easily by sucrose, which used to be much more expensive.  Now, because of the use of corn for ethanol, sucrose is only slightly more expensive than HFCS.

Click on the Table to see the overall 13% growth in sales over the last year, with products like HFCS-free milk drinks, juices, salad dressings, and teas registering 1,500% to 16,000% increases.  Like “trans fat-free,” the term “HFCS-free”  is a calorie distractor.  It too will make you forget about the calories.

The irony is that white table sugar – formerly a leading target of “eat less” messages – suddenly has a health aura.  Marketers have wasted no time moving in to use that aura to sell the same old products.

May 22 2009

HFCS is the new trans fat?

Will the confusion about sugars never end?  A recent study reconfirms the metabolic problems caused by too much fructose, but public opinion continues to blame High Fructose Corn Sweeteners (HFCS) as the new dietary evil.   HFCS isn’t really high in fructose.  It has about the same amount of fructose as common table sugar.   Both are about half fructose and half glucose, and both cause metabolic problems when you eat too much of them.  So go easy on the sugars!

Here’s what the New York Times has to say about the study.

Feb 15 2009

Sales of HFCS-free foods zoom up

The bad press about high fructose corn syrup (HFCS) is having an effect.  According to figures assembled by Phil Lempert, the Supermarket Guru, sales of products bearing “HFCS-Free” labels almost reached a billion dollars last year.  Fruit drinks are the biggest HFCS-free category, but HFCS-free yogurts, vegetable juices, and breads are the fastest growing. Lempert doesn’t say what companies are using instead of HFCS.  If it’s sucrose, it won’t be much of an improvement.  But no wonder the Corn Refiners think they need a hefty public relations campaign.

March 21 update: This trend is a front-page story in the New York Times.

Jan 27 2009

Mercury in high fructose corn syrup

Never a dull moment.  The Institute for Agriculture and Trade Policy (IATP), a think-tank in Minneapolis, tested brand-name foods made with high fructose corn syrup (HFCS) and found about half of them to contain mercury.  HFCS, it seems, is made by a process that involves lye, which in turn is made in chlorine – alkali plants by a method that uses mercury. Mercury is a neurotoxin, although not as bad a toxin as methymercury, the kind that accumulates in large, predatory fish. A scientific report published in Environmental Health says the amounts of mercury in HFCS ranged from 0.00 to 0.57 micrograms per gram. The IATP’s bottom line: the process for making HFCS should be changed to one that does not introduce mercury.

This seems like quite sensible advice, but how worried should we be about mercury in HFCS? I agree that mercury in any form is unlikely to be good, but I have no idea whether such low levels do measurable harm.  For one thing, these studies did not compare the amounts of mercury found in HFCS to those typically found in foods that do not contain HFCS.  My guess is that most foods contain low levels of mercury because mercury is prevalent in air, water, and soil, especially around coal-burning power plants.  Also, soft drinks are the major sources of HFCS in American diets, but these were found to be relatively free of mercury.  This is puzzling.

If anything, these studies are a call for more research on heavy metal toxicology.  In the meantime, let’s lobby for changing this process for making HFCS, but even more so for cleaning up coal-burning power plants that supply 40% of mercury in our environment.

Update January 28: Food Production Daily has a good report on this, with quotes from the Corn Refiners.

Dec 13 2008

Those pesky HFCS commercials: a reaction

The makers of the terrific movie, King Corn, must have a bit of time on their hands.  Inspired by the Corn Refiners’ commercials for high fructose corn syrup (HFCS), they have created a spoof.  Enjoy (?)

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