The Relationship Between Sugar And LDL Cholesterol

Why would someone have too much of the "really bad cholesterol" and still have normal amounts of LDL? The answer turns out to be that sometimes the body benefits from having LDL in the bloodstream rather than inside cells that use it.

Only the smaller pieces of LDL cholesterol "fit" the receptor sites that line the arteries. There is a part of the LDL molecule that fits inside the molecule on the surface of the receptor, something like a lock in a key. If the LDL "key" matches with the receptor's "lock," then it is absorbed into the cell from the bloodstream.

When there's a lot of sugar in the bloodstream, however, the LDL molecule can become glycated. This process is a little like getting "gunk" on a key, so much that it won't fit into its lock any more. A specific, 67-atom segment of the LDL molecule is susceptible to glycation by sugars that change its shape so it cannot be taken up by receptors and taken out of the bloodstream.

When you consume a lot of sugar, LDL stays in your bloodstream. When you consume a lot of fructose, the problem is magnified even more.

Glucose is among the least reactive of all the sugars that circulates in your bloodstream. Fructose is 12 to 13 times as likely to "stick" to LDL cholesterol. Fructose is the kind of sugar in fruit, and it's also the kind of sugar in high-fructose corn syrup, used to sweeten cereals, baked goods, and snack foods in the United States and Canada. There is research that suggests that the critical level of sugar is 13 to 25 percent of total calories, or about what a typical American eats every day. If you were to reduce other forms of carbohydrate consumption to make up for sugar consumption, the effects would not be as severe, but very few people do.

The first 25 grams or so of fructose you consume (that's the equivalent of two pieces of most kinds of fruit) is used as fuel by the liver. This relatively small amount of fructose actually accelerates your liver's ability to deal with glucose, which the body digests from other kinds of carbohydrate foods. More than 25 grams of fructose overwhelms the liver, and fructose is left in circulation, where it can interact with LDL. 

Since the liver also is a major clearing house for LDL cholesterol, chemically altering LDL gives the liver greater opportunity to clear out fructose, which would be more damaging to the body than LDL. However, it's very simple to keep this unexpected elevation of LDL levels from every happening in the first place: Don't eat products sweetened with high-fructose corn syrup. Don't eat too much table sugar, either, because sucrose breaks down into the relatively safe glucose and the relatively toxic fructose.

For most of us, it really isn't fatty foods that raise our cholesterol, particularly our "bad" cholesterol. It's sugar. Even if you were to eat 24 eggs a day, your body simply cannot absorb enough cholesterol from the food you eat to give you high cholesterol (except in the case of a relatively rare genetic condition called familial hypercholestolemia). Your body has to make most of its cholesterol. It can't use that cholesterol, however, when sugar levels are too high. Lower your sugar consumption to lower your LDL.