Chapter 13, Problem B4CR

Effects of Dietary Fats on Lipoprotein Levels Cholesterol that is made by the liver or that enters the body from food does not dissolve in blood, so it is carried through the bloodstream by lipoproteins. Low-density lipoprotein (LDL) carries cholesterol to body tissues such as artery walls, where it can form deposits associated with cardiovascular disease. Thus, LDL is often called bad cholesterol. Highdensity lipoprotein (HDL) carries cholesterol away from tissues to the liver for disposal, so HDL is often called good cholesterol. In 1990, Ronald Mensink and Martijn Katan published a study that tested the effects of different dietary fats on blood lipoprotein levels. Their results are shown in Figure 2.23. Figure 2.23 Effect of diet on lipoprotein levels. Researchers placed 59 men and women on a diet in which 10 percent of their daily energy intake consisted of cis fatty acids, trans fatty acids, or saturated fats. Blood LDL and HDL levels were measured after three weeks on the diet; averaged results are shown in mg/dL (milligrams per deciliter of blood). All subjects were tested on each of the diets. The ratio of LDL to HDL is also shown. Source, Mensink RP, Katan MB, Effect of dietary trans fatty acids on high-density and low-density lipoprotein cholesterol levels in healthy subjects. NEJM 323(7):43945. An elevated risk of heart disease has been correlated with increasing LDL-to-HDL ratios. Rank the three diets according to their predicted effect on cardiovascular health.

Some nutritionists claim that the secret to long life is to be slightly underweight as an adult. If a persons weight is related partly to diet, partly to activity level, and partly to genetics, what underlying factors could be at work to generate statistics that support this claim?

Excess carbohydrates and proteins are stored as _____. a. amino acids b. starches c. fats d. monosaccharides

The food label in Figure 11.28 lists the nutrients and other substances in a package of ready-to-eat macaroni and cheese. Based on your reading in this chapter, how would you rate this products healthiness in terms of fats and carbohydrates? Figure 11.28 Food labels are useful health tools. Information on a food label can be used to ensure that you get the nutrients you need without exceeding recommended limits on less healthy substances such as salt, sugar, and trans fats. At present, the USDA is considering major revisions to food labels. The proposed changes include showing realistic serving sizes and sugars added by the manufacturer, and printing the calorie content per serving in larger, bolder type so that it is easier for consumers to make informed choices about purchases of prepared foods. (Left: USDA, US Department of Agriculture; Right: FoodCollection/SuperStock)