Chapter 3, Problem 2SC

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?

How does RNA differ from DNA?

What is the function of DNA?

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

Which of the following statements is not true? a. Essential nutrients can be synthesized by the body. b. Vitamins are required in small quantities for bodily function. c. Some amino acids can be synthesized by the body, while others need to be obtained from diet. d. Vitamins come in two categories: fat-soluble and water-soluble.

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. In which group was the level of LDL (bad cholesterol) highest?

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.

Discuss how carbohydrates can be stored as fat.

As a person ages, the number of body cells steadily decreases and energy needs decline. If you were planning an older persons diet, what kind(s) of nutrients would you emphasize, and why? Which ones would you recommend an aging person eat less of?