Cholesterol: Down With the Bad, Up With the Good

You’ll never look at a cave painting and see an ad for cholesterol lowering drugs. There are also no ads for the yummy, yet less-than-healthy foods that dominate the modern diet. Advances in the technology of food have yielded countless alternatives to the grasses, roots, nuts, berries and meat gathered by hand, prepared simply and eaten whole. Today, consumers do not face the daily challenge of avoiding predators. Instead, we strive to escape the danger of our own dietary habits that, while far less scary than a brontowhatsit, are just as lethal, particularly in terms of cholesterol.

Hitching a ride

Cholesterol itself is not bad. It is a vital element for cell membranes, hormones, vitamin D and bodily processes such as digestion. Our liver manufactures roughly three-fourths of the cholesterol in our blood. The remaining fourth comes from dietary sources such as meat, poultry, fish and dairy products. When we eat, the liver pulls cholesterol from the bloodstream. Between meals, the liver secretes cholesterol back into the blood as needed.

But cholesterol is a lipid—a fat-like substance that is not soluble in aqueous systems like our blood. Unable to travel on its own, cholesterol is carried by lipoproteins, small bundles with fat on the inside and protein on the outside. These carriers are distinguished by their density, a function of the ratio of protein to lipid.

Low density lipoproteins, LDL, carry cholesterol from the liver out to the body. Commonly referred to as “bad cholesterol,” LDL in the blood can build up as plaque on the inside of arteries, hindering blood flow and eventually causing a heart attack or stroke. High density lipoproteins, HDL, carry cholesterol from the various parts of the body back to the liver for reuse or excretion. Referred to as “good cholesterol,” HDL is believed to reduce LDL build-up. Blood cholesterol levels to shoot for are less than 200mg/dl (milligrams per deciliter of blood) for total cholesterol, less than 100mg/dl for LDL, and more than 60mg/dl for HDL.

Do or diet

Dietary effects on cholesterol levels are vast, although not as clear as you might think. The American Heart Association (AHA), Dallas, recommends a daily intake below 300 mg cholesterol per day; 200 mg for those with heart disease. According to AHA, though, understanding which fats increase LDL is the first step toward reducing the risk of heart disease. Research has shown that elevated cholesterol, especially LDL, is more dependent upon the type of fat in food rather than the presence of cholesterol. Studies have shown that high levels of saturated fatty acids are linked with high LDL levels. Consider fat from coconuts vs. pork. Pork fat has roughly 95 mg cholesterol per 100 gram, and approximately 56% unsaturated fatty acids, according to USDA’s National Nutrient Database for Standard Reference. Coconut oil, being non-animal in origin, contains no cholesterol. With approximately 86% saturated fatty acids, however, coconut oil is on AHA’s list of fats to avoid, right along with pork fat. Pro-coconut groups like the Coconut Research Center, Colorado Springs, CO, disagree, arguing that coconut oil’s saturated fatty acids are predominantly medium-chain fatty acids that actually help increase HDL and reduce the risk of heart disease.

Similar increases in understanding have changed perspectives on another food once believed to be a cholesterol-elevating agent – eggs. Although high in cholesterol (423mg/100g), eggs are low in saturated fatty acids (3%) meaning they will have minimal effect on blood lipids

Turns out, saturated fatty acids are the primary culprit in LDL elevation. Fatty acids contain no double bonds. Their carbon atoms are “saturated” with hydrogen atoms, allowing for the chains to pack tightly together, typically resulting in a fat that takes a solid form at room temperature. AHA recommends a limit of 7% of total daily calories come from saturates.

All saturates are not created equal, though. Unlike common saturates lauric, myristic, and palmitic acids, stearic acid has been shown to have a neutral effect on LDL levels. Stable through storage and cooking, stearic acid can be used to create spreadable solids such as shortenings, margarines, and spreads, or as a cream base for baked items.

When one or more carbon pairs are joined with a double bond, the fatty acid is referred to as “unsaturated.” Fats with one double bond are referred to as “monounsaturated.” Fats with more than one double bond are called “polyunsaturated.” Replacing dietary saturates with unsaturates helps avoid LDL elevation. Oils contain varying amounts of mono- and polyunsaturated fatty acids. Canola and olive oils are high in monounsaturates, approximately 63% and 73%, respectively. Safflower and soybean oils deliver 77% and 61% polyunsaturates, respectively.