Absorption of vitamin B12 may be decreased in older adults ...

[notis]

Absorption of vitamin B12 may be decreased in older adults because of decreased
 
  a. intestinal motility.
  b. production of bile by the liver.
  c. production of intrinsic factor by the sto-mach.
  d. synthesis of vitamin B12 by intestinal bac-teria.

Question 2

Most recommended levels of intake for vitamins and minerals do not change with aging. An exception to this is the recommended dietary allowances of vitamin D, which are higher in adults over age 50 years.
 
  What causes the body's need for vitamin D to increase over the age of 50 years? A) The ability to absorb calcium, which decreases with age
  B) The potential risk for coronary heart disease, which uses vitamin D
  C) The increased consumption of coffee and tea interferes with vitamin D synthesis
  D) The ability to synthesize vitamin D from sunlight, which decreases with age

[zhanghao]

Answer to Question 1

C
Older adults may produce less intrinsic factor, which may decrease vitamin B12 absorption. Vi-tamin B12 absorption is not affected by intestinal motility or bile production. Bacterial vitamin production occurs in the large intestine, after most vitamin B12 absorption has occurred, so bac-terial production is not very important.

Answer to Question 2

D
Feedback:
An older adult needs increased supplements of vitamin D due to the ability to synthesize vitamin D on the skin from sunlight decreases with age.