Chapter 15, Problem 6RQ

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

The pH of human stomach acid ranges from 1.0 to 3.0, whereas a healthy esophagus has a pH of approximately 7.0. In gastroesophageal reflux disease (GERD), often called acid reflux, stomach acid flows backward from the stomach into the esophagus. Repeated episodes in which esophageal pH goes below 4.0, considered clinical acid reflux, can result in bleeding ulcers and damage to the esophageal lining. The data in the Figure, from a patient with GERD, show esophageal pH during a sleeping reflux event. How many minutes does it take to go from the peak of the reflux event (when pH is most acidic) to when the reflux event is over? Source: Based on T. Demeester et al. 1976. Patterns of gastroesophageal reflux in health and disease. Annals of Surgery 184:459469.

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.