Nutrients such as fats and proteins are both produced by the body and consumed in the diet. On the other hand, many other nutritional components cannot be synthesized by the body and must be obtained in food. Which of the following substances can a healthy adult synthesize?
A. The fatty acid linoleic acid B. The glucogenic amino acid histidine C. The ketogenic amino acid leucine D. The micronutrient folic acid E. The micronutrient vitamin K
The glucogenic amino acid histidine-the correct answer is b. the eight essential amino acids (those that the body cannot synthesize and must be supplied by diet) are leucine, lysine, isoleucine, phenylalanine, tryptophan, methionine, threonine, and valine. arginine and histidine can be synthesized, but can become essential during times of intense anabolic states such as infancy, growth spurts, and recovery from infectionanswer a is incorrect. the essential fatty acids are linoleic and linolenic acid. they are ubiquitous in natural dietsanswer c is incorrect. both ketogenic amino acids are essential and begin with the letter l (leucine and lysine). they must be supplied by dietary intakeanswer d is incorrect. folic acid is produced by symbiotic bacteria from the precursor paminobenzoic acid. this production is inhibited by sulfa antibiotics. folic acid cannot be produced through cellular metabolism. folicacid is also obtained from leafy vegetables and cereal. supplementation is recommended for pregnant women to prevent congenital neural tube defectsanswer e is incorrect. vitamin k is synthesized by the microflo ra in the gut. it is also found in green leafy vegetables. patients on warfarin therapy should be advised to maintain a stable intake of these vegetables from day to day, in order to achieve a therapeutic international normalized ratio that does not fluctuate.