Vitamin D is a fat soluble vitamin, and so will be better absorbed when taken with a meal that contains fat. The other vitamins listed may be better absorbed with food, but do not require fat for transport across intestinal membranes, as they are water-soluble. 

Conditionally essential amino acids are those that can be produced by the body under normal circumstances, but may not be able to be produced during certain situations, such as certain disease states or severe catabolic stress. Arginine is the only conditionally essential amino acid listed. Histidine and methionine are both essential amino acids, while aspartic acid is a non-essential amino acid.

Vitamin C is one of the body's most important antioxidants. Antioxidants are reducing agents - that is they themselves get oxidized. Recall: OIL RIG. Thus antioxidants such as vitamin C are electron donors, able to stabilize the free radicals produced by various metabolic processes in tissues and extracellular spaces. Vitamin E (not listed) is another important antioxidant and is actually more potent than vitamin C.

While all of the substances listed are present in gastric secretions and are necessary for normal digestion, intrinsic factor is the only one that has a direct role in vitamin B12 absorption in the small intestine. Deficiencies in intrinsic factor due to genetic variation or damage to stomach lining can result in pernicious anemia, a type of anemia that is caused by insufficient levels of B12.

The digestion of dietary carbohydrates is initiated by amylase, an enzyme present in saliva. This enzyme breaks down long carbohydrate molecules into shorter units such as disaccharides. Lipase breaks down fats and is not present in the saliva, rather it is secreted by the pancreas into the duodenum. Pepsin is a protease - an enzyme that breaks down proteins. This enzyme is secreted by the chief cells of the stomach in its zymogen form (pepsinogen). It is activated by the product of the parietal cells (hydrochloric acid). Note that amylase is also secreted by the pancreas to complete the chemical digestion of carbohydrates into monosaccharides so that they can be absorbed by the brush border of the small intestine.

Bile is produced exclusively in the liver. It may then be stored in the gall bladder so that it can be released during digestion of a fatty meal. No bile is produced in the stomach, nor the duodenum. The vast majority of bile is cholesterol-derivatives that stick to dietary fiber and are excreted along with the fiber. Thus increasing fiber is (mainly soluble) is an effective way to decrease cholesterol.

Manganese, found in oats, brown rice, chickpeas, and spinach, is a cofactor for the enzymes that produce the amino acid proline. Proline is essential for collagen shape and integrity, and is an amino acid, not a cofactor. Other important minerals required for collagen production include copper, zinc, vitamin C, and iron.

Children ages 1-18 are at the highest risk for physiological changes due to malnutrition. Significant nutritional deficiencies at this age can cause failure to thrive, stunted growth, long-term brain damage, and increased incidence of cardiovascular and metabolic disease later in life.

Prolonged laxative use can lead to hypokalemia and hypocalcemia. This is due to alterations in gastrointestinal absorption and excretion of potassium and calcium. Magnesium can also be depleted during long-term laxative use, but chromium is unlikely to be affected. Zinc, copper, manganese, and selenium are also not generally impacted by normal laxative use.

Dark leafy greens such as kale, collard greens, and chard have among the highest levels of vitamin K of any food. The other foods listed: beets, sweet potatoes, and pumpkin all have very low vitamin K content, and are safe for a patient on a warfarin diet.