If I told you that daily sugar consumption by Americans was over 20 teaspoons, you would probably agree. Teaspoons aren’t that big and sugar is in everything these days – beverages, breads, processed foods and of course, candy. But 20 teaspoons of sugar a day equals roughly 140 pounds of sugar per year. Compared to the early 1900s when Americans consumed an average four pounds of sugar a year.
Sugar is a simple carbohydrate and is found naturally in many foods such as fruits and vegetables. We actually need it to survive and our bodies have evolved to consume sugar seasonally. Consider in the Pacific Northwest that leafy greens (ground cover in forests), berries (fruits) and roots (vegetables) rotate in bloom for six to eight months, providing indigenous diets with the natural sugars needed for energy, stabilize blood sugars and brain function. When dried, cured or preserved for winter use, indigenous peoples had access to sugar, but in the winter months they were less active and didn’t need the same amount as needed during the hunting and summer seasons.
Our bodies require glucose (simple sugar found naturally in most fruits and vegetables), to stimulate the pancreas to produce insulin. The brain is triggered by in the increase in insulin and tells the body that we’ve had enough food. This communication signal is also known as the hormone Leptin. Not all sugars are good for the functions of leptin; too much suppresses the communication channels of and our bodies don’t think we have “filled our tank.”
High fructose corn syrup and sucrose, another naturally occurring sugar, contain large amounts of fructose, a third naturally occurring sugar. While glucose in low amounts is good for our metabolic functions, sucrose and fructose are not healthy in more than low doses because of how they are processed by the body. They are quickly metabolized by the liver and stored as fat.
For example, one 12-ounce cola, sweetened with HFCS hits the liver with a high dose of sugars causing it to metabolize immediately, sending mixed signals to the brain and body. While glucose helps leptin talk to the brain, fructose shuts leptin down. Thus after one cola the brain thinks we are still hungry and doesn’t signal the body to stop consuming calories.
Fructose isn’t all bad though, it actually has practical purposes for fast energy that will be quickly metabolized and used. HFCS provides glycogen supplies at a fast rate that is practical for professional athletes who consume sports drinks high in HFCS during races and endurance training. In the days when our ancestors hunted for survival, plants high in fructose were eaten to keep up energy levels for the enduring hunt. However, for the rest of us today whose daily physical activities don’t include endurance training, racing or hunting for survival, fructose is dangerous.
What is the impact of this communication breakdown? First, our bodies have not evolved at the same rate as our environments have changed. Gerald Reaven, a pioneering diabetologist at Stanford University, studies how fructose impacts metabolic syndrome and insulin resistance. “If you want to cause insulin resistance in laboratory rats, feeding them diets that are mostly fructose is an easy way to do it. It’s a very obvious, very dramatic effect.”
Michael Pagliassotti, biochemist at Colorado State University who conducted many relevant animal studies in the late 1990s and early 2000s, studied well established biochemical explanations for what was happening to rats when fed pure fructose diets. “Their livers convert the fructose into fat that supposedly gives us heart disease when we eat it by raising LDL cholesterol. The fat accumulates in the liver, and insulin resistance and metabolic syndrome follow.”
Pagliassotti continued, “These changes can happen in as little as a week if the animals are fed sugar or fructose in huge amounts — 60 or 70 percent of the calories in their diets. They can take several months if the animals are fed something closer to what humans (in America) actually consume — around 20 percent of the calories in their diet. Stop feeding them the sugar, in both cases, and the fatty liver promptly goes away, and with it the insulin resistance.”
Both Reaven and Pagliassotti stated similar observations about the studies saying affects can be reversed over a period of time, but not all studies have concluded what amount of sugar intake is too far where symptoms of diabetes, heart disease and obesity in rats is not reversible, but instead deadly.
Gary Taubes is an independent investigator in health policy at Robert Wood Johnson Foundation and an author of “Why We Get Fat.” He asks a brilliant question that is yet to be answered, “How much of this stuff do we have to eat or drink, and for how long, before it does to us what it does to laboratory rats? And is that amount more than we’re already consuming?”
“If sugar just makes us fatter, that’s one thing. We start gaining weight, we eat less of it. But we are also talking about things we can’t see – fatty liver, insulin resistance and all that follows.” Studies are still being conducted and results are inconclusive, but as Taubes observes from meta-studies he actively follows, “It very well may be true that sugar and high-fructose corn syrup, because of the unique way in which we metabolize fructose and at the levels we now consume it, cause fat to accumulate in our livers followed by insulin resistance and metabolic syndrome, and so trigger the process that leads to heart disease, diabetes and obesity. They could indeed be toxic, but they take years to do their damage. It doesn’t happen overnight. Until long-term studies are done, we won’t know for sure.