Biologically based health practices
Biologically based health practices include methods in conventional medicine, complementary and alternative medicine and traditional medicine. They share the characteristic that substances used in the practice come from plants or animals, sometimes with very little change to the natural material and sometimes with extensive preparation. Laboratory methods may become involved in monitoring the quality and concentration of an active constituent whose properties are known.
In some cultures, assuming the active principle of the biological material can be characterized chemically or, with living organisms, by genetic methods, the principle may be made synthetically. It can be argued if a synthetic or cultured copy is still within the scope of biologically based practice, but, in cases such as a chemical that comes from an endangered plant species, synthesis may be the only practical way to ensure both an adequate supply of the phytochemical and the continued existence of the species. Synthesis may be the only ethical way to obtain clinically useful quantities of a chemical manufactured by the human body, such as insulin.
Originally, insulin came primarily from slaughtered pigs, and some individuals might be allergic to porcine insulin. When it became feasible to synthesize adequate supplies of insulin identical to that made by a normal pancreas, that became preferred. Since insulin is usually injected in periodic doses rather than secreted by the pancreas, molecular modifications were made to change the duration of action of a dose of insulin, while still having the same role in sugar metabolism, it can be argued if this is, or is not, a biologically derived practice.
The optimal half-life and bioavailability of insulin needs to be indivualized for each patient; insulin therapy often involve self-monitoring and adjusting the dose. Interestingly, porcine insulin remains available, because its particular bioavailability patterns is better, for certain patients, than human insulin.
Technique versus intention
The line between mainstream and CAM can be a thin one. For example, vitamin supplementation may be ordered by a physician for various reasons. These can include a diagnosed vitamin deficiency or a state (e.g., childhood growth, pregnancy) that increases the requirement. In these examples, the doses may be larger than in food or mild supplements, but not immensely so.
In some cases, far larger doses than are required for nutrition may be prescribed; this is called a pharmacologic dose because the vitamin is no longer being used strictly for its basic role in nutrition, but to use certain properties of "megadoses" that have specific effects. One of the best-known mainstream uses of vitamins in pharmacologic doses is niacin for various disorders of lipid (i.e., fat), cholesterol, or lipoprotein metabolism.
It is quite mainstream to treat a deficiency disease caused by a vitamin-poor diet, such as scurvy from a lack of Vitamin C. Megadoses of vitamin C to prevent or treat upper respiratory infections, however, have not demonstrated efficacy in randomized controlled trials and are not considered mainstream.
A general diet might be prescribed conventionally as part of treatment, such as low-nitrogen in renal failure or gluten-free in the presence of gluten allergy. Some diets, however, have been claimed to treat diseases where no deficiency or allergy is known. For example, the Gerson diet has been recommended to treat various cancers.
Dietetics is the mainstream practice of controlling diets to correct known deficiencies, to limit intake of nutritional factors that a given patient has difficulty in metabolizing, to avoid drug interactions, and to avoid individual allergies and sensitivies. Nutritional medicine is the CAM practice of treating serious diseases principally with dietary change, to the exclusion of drugs and surgery, and without substantial evidence of efficacy.
Representative prescribed diets
For patients in end stage renal disease, especially on dialysis, their limited kidney function can best process a diet with reduced protein, fluid, and some minerals. Supplemental Vitamin D and calcium often are prescribed, depending on laboratory monitoring and the state of their bones. 
Nutritional medical techniques
One example is the Gerson diet. This is intended as a primary mode of treatment; all drugs used with it are considered to be of biologic origin.
This biologically practice is based on the use of essential oils obtained from plants, most commonly administered by inhalation. There are trials of other methods of administration, such as massage with essential oils.
Often called herbalism, phytotherapy is the use of plant-derived substances to treat specific disease. Unquestionably, many plant-derived chemicals are effective drugs, such as opium and digitalis. As discussed in phytotherapy, the problem of using minimally processed natural materials may be variability in concentration among individual plants.