Use and Abuse of the Glycemic Index

While I want to make it clear that I’m not denying the importance of insulin, I think that the importance of the GI of foods is nowhere near as useful to non-diabetics as it’s made out to be.

The way I see people talking about the GI of foods seems to indicate that they think a low GI gives them a free pass. What really ticks me off in particular is agave syrup. A food having a low GI can mean either that it’s digested slowly because it contains fiber, fat or protein. It can also mean, as it does in the case of agave syrup, that it’s almost entirely fructose. Fructose is metabolised in the liver and turned into fatty acids (raising your cholesterol and, more importantly, your triglycerides). Your body then uses it as energy or stores it as fat. Glucose is hits your bloodstream more directly and raises blood sugar. Your body either uses it or turns it in to fat to store for later.

Either way, it winds up as fat attached to your backside.

You’re better off considering the actual carbohydrate and caloric content (though you don’t have to count fiber) than you are the glycemic index. Coca-Cola has a GI of 63 (medium), and Cantaloupe has a GI of 65. Which one is better for you? Coke has 33g of sugar in a 12oz can. One-quarter of a cantaloupe has 16g of sugar, yet Cantaloupe’s GI is a little higher than Coke’s. Which is more fattening?

Let’s pretend you don’t care about your waistline. This is from a 2005 paper called “Fructose, insulin resistance, and metabolic dyslipidemia”.

These metabolic disturbances appear to underlie the induction of insulin resistance commonly observed with high fructose feeding in both humans and animal models. Fructose-induced insulin resistant states are commonly characterized by a profound metabolic dyslipidemia, which appears to result from hepatic and intestinal overproduction of atherogenic lipoprotein particles. Thus, emerging evidence from recent epidemiological and biochemical studies clearly suggests that the high dietary intake of fructose has rapidly become an important causative factor in the development of the metabolic syndrome.

Not generic “sugar” but specifically fructose: the sugar that doesn’t raise GI too much. It still messes you up. This is from the same paper:

Fructose is readily absorbed and rapidly metabolized by human liver. For thousands of years humans consumed fructose amounting to 16–20 grams per day, largely from fresh fruits. Westernization of diets has resulted in significant increases in added fructose, leading to typical daily consumptions amounting to 85–100 grams of fructose per day. The exposure of the liver to such large quantities of fructose leads to rapid stimulation of lipogenesis and TG [triglyceride] accumulation, which in turn contributes to reduced insulin sensitivity and hepatic insulin resistance/glucose intolerance.

So, no help there. Honey and Agave Syrup both have about 60 calories per tablespoon. Agave is mostly fructose, and honey about half fructose and half glucose. Table sugar actually has fewer calories per tablespoon (48), and it’s all sucrose. Maple syrup is mostly sucrose with a tiny amount of fructose and a little glucose and has 52 calories per tablespoon.

What matters with sweeteners is how much of them you use. They are 99-100% sugar, so it’s really just a matter of which one you like best. There’s nothing special about any new-fangled sweetener like agave syrup or brown rice syrup (GI 25). A low GI is not going to save you from any one of the calories from sugar that it contains, and high-fructose sweeteners might be even worse than other sugars.

And, my final point: You shouldn’t cut yourself a break on Agave syrup. People seem to think it’s more natural, but that’s just not so. It can’t compete with maple syrup or honey on that score.

“If fructose were natural, I would be able to go out to corn field and get a bucket of sweetener. I can go to a beehive and get honey that I can eat without processing it. I can go to an apple tree and pick an apple and eat it. I cannot go out into a cornfield, squeeze corn, and get fructose syrup, and I cannot go into an agave field, and get the product sold on retail shelves, as agave syrup. Falsely labeled agave fructose and high fructose corn syrup are both products of advanced chemistry and extensive food processing technology.”

Later in the same article:

“The simple answer tends to be the correct one. There is no land of milk and agave. Milk comes from goats, cows, humans, etc., and honey comes from bees. What I want people to understand is that mislabeling a sweetener like agave syrup is about money and profit, to the real determent of your health. The unethical factor is that the natural health food business has gone to great lengths in the case of agave to defraud consumers, by deceiving and lying to those who are trying to seek better health. There is something ethically worse about a company pretending to sell something all natural to people seeking health, than a mainstream company not pretending that their food is healthier. For example, nobody selling fast and junk foods is advocating it is health food. When you are in a natural health food store, you expect to pay extra money for something that is good for you. We have con artists here, pretending to deliver better health at a higher cost, when in reality it is equal to, or much worse than the many other sweeteners or harmful junk food. People are expecting to receive health, and are intentionally being defrauded for profit.”

Caveat emptor!

(Both quotes above are from Russ Bianchi, Managing Director and CEO of Adept Solutions, Inc., a global food and beverage development company.)