Tuesday, June 23, 2009

The Corn Syrup Blues

This post is a response to the propaganda--er, comment--I received yesterday from the Corn Refiners Association on my post about giving up sugar and refined flour. I've been aware that the Corn Refiners Association launched a huge campaign awhile back, but I don't watch t.v. or or read newspapers or magazines, so this is the first time I actually saw one of their ads.

That they have someone actually sitting there every day (the poor sap), watching for every little blog post that mentions corn syrup--it boggles the mind. They are obviously spending millions and millions on a campaign that I can only imagine looks absolutely ridiculous to most people. That's how it looks to me anyway.

Before I really launch into this, here's the blurb they sent:

High fructose corn syrup, sugar, and several fruit juices are all nutritionally the same.

High fructose corn syrup is simply a kind of corn sugar. It has the same number of calories as sugar and is handled similarly by the body. There is no scientific evidence to suggest that high fructose corn syrup is responsible for diabetes. It is especially important to understand that Americans are consuming more calories from all types of foods today than what was consumed 30 years ago. And we expend less energy to burn the extra calories. Consider the numbers reported in the February 2009 Loss-Adjusted Food Availability Data by the USDA. Total caloric intake on a per capita basis for Americans increased from 2,172 calories per day in 1970 to 2,775 calories per day in 2007 – an additional 603 calories. Where are all these calories coming from? Major contributors to this 603-calorie increase include 299 calories from added fats and 194 calories from flour and cereal products. Added sugars account for 57 calories of the daily increase.

The American Medical Association in June 2008 helped put to rest misunderstandings about this sweetener and obesity, stating that “high fructose syrup does not appear to contribute to obesity more than other caloric sweeteners.”

Even former critics of high fructose corn syrup dispel long-held myths and distance themselves from earlier speculation about the sweetener’s link to obesity as the American Journal of Clinical Nutrition releases its 2008 Vol. 88 supplement's comprehensive scientific review.Consumers can see the latest research and learn more about high fructose corn syrup at http://www.sweetsurprise.com/.

Audrae Erickson

President

Corn Refiners Association


So, is corn syrup really no different than sugar?

Well, aside from the fact that it's laced with mercury and made from mostly genetically modified corn (okay, sugar beets are now genetically modified, too) are there any other distinctions?

High fructose consumption leads to what is called fructose malabsorption or dietary fructose intolerance. Everyone who consumes more than about 25 to 50 grams of fructose in one sitting suffers fructose intolerance, as the intestines are only able to absorb that much at one time. But some people are truly intolerant in that they are only able to absorb much smaller quantities of fructose. It's the unabsorbed fructose which causes problems by passing on from the small intestine to the large intestine where it begins to ferment.

A can of soda contains about 15 or 16 grams of fructose, so you can see how easy it would be for a person with even a normal tolerance for fructose to have problems if they drink more than one soda in a sitting.

Once the excess fructose ferments in the gut, people will experience gastrointestinal symptoms such as gas, bloating, cramps, constipation, and diarrhea. Beyond that, according to wikipedia, malabsorption of fructose causes reduced levels of tryptophan, folic acid and zinc in the bloodstream.

The University of Iowa did a study on fructose malabsorption and has a nice page summarizing their findings. One interesting thing they note is that when they tested people with unexplained IBS (irritable bowel syndrome) they found that 30% of the subjects were fructose intolerant. So, a significant number of IBS cases may simply be a result of fructose intolerance or pure overconsumption of fructose. Imagine that.

What is disappointing in the Iowa report is their suggestion that the next step should involve a search for ways to make fructose more absorbable. Sure, that will keep it out of the large intestine, but dumping it into the bloodstream is not the answer. Don't these researchers ever consider that there might be a reason the body limits the amount of fructose it can absorb?? Why would you want to override that system? Instead of that, how about counseling your patients to restrict their intake of fructose.

But moving on. Once the fructose is in the bloodstream is it really true, as the Corn Refiners Association asserts, that the body handles it like it handles sugar, and that there is no evidence linking it to diabetes and obesity?

Before diving into the medical studies, it would be helpful to read this excellent article on insulin, leptin and blood sugar. It does an excellent job of explaining the complicated processes involved in metabolizing sugar. The key piece in the article that will help us understand the research on high fructose corn syrup concerns the role of leptin in regulating appetite:

When leptin levels get high enough, meaning you have eaten enough, then leptin permeates into your brain and tells your subconscious brain you are full. At the same time the higher levels of leptin are also telling your pancreas that you are full, which turns off the beta cell production of insulin, as no more taxis are needed.

If you ate the right amount of food for your physical activity level then blood sugar always has some place healthy to go, insulin rises and falls in a controlled manner, as does leptin.

When insulin has too many blood sugar passengers and cells don't need any sugar, then insulin stimulates the production of triglycerides (which can become stored fat). This is how you gain weight. Unfortunately, as triglycerides elevate in your blood they get in the way of leptin getting into your brain. This keeps you eating more than you need to because you don't have a full signal yet, a problem called leptin resistance. This encourages even further insulin-driven triglyceride formation, making it more likely you will gain weight.


Now let's look at the research. This article in The Journal of Clinical Endocrinology and Metabolism found that consumption of high levels of fructose resulted in lower concentrations of circulating insulin and leptin and concluded:

Because insulin and leptin, and possibly ghrelin, function as key signals to the central nervous system in the long-term regulation of energy balance, decreases of circulating insulin and leptin and increased ghrelin concentrations, as demonstrated in this study, could lead to increased caloric intake and ultimately contribute to weight gain and obesity during chronic consumption of diets high in fructose.


Another study, in the journal Diabetes, concluded that a high fructose diet led to increased insulin resistance in both liver and adipose tissues, and dyslipidemia (which usually means increased triglycerides and/or increased cholesterol levels).

Here's another study, out just last month: Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans.

I could go on, but I think I've made my point. Even a layperson such as myself can quickly find evidence to refute the statements made by the Corn Refiner's Association. It's not hard to do. They make such a point about how the use of caloric sweeteners hasn't gone up dramatically and that fats and flour consumption have gone up far more dramatically. They fail to mention the astounding increase in HFCS consumption over sugar consumption, and ignore the research that shows that HFCS consumption disrupts the signalling of leptin in the brain that tells you you're full. So, of course people are eating more of all things, but that doesn't mean that corn syrup isn't a major culprit.

Eat corn syrup, never feel full, eat more of everything.

To close, here's one of Dr. Mercola's (many) cogent discussions on this issue:
Dramatic Example of How the Food Industry Lies to You About Corn

2 comments:

  1. Well done! Good post.

    ReplyDelete
  2. I avoided for 9 months any product that has corn syrup, I eat bread(french bread and not sliced bread that stays fresh a month), I do not exercise and I lost 20 lbs with no effort. Is this a proof or what?

    ReplyDelete