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The Science of Nutritional Medicine

The Science of Nutritional Medicine:


Alan Gaby. M.D.ALAN GABY, M.D.

Helping patients successfully modify their dietary habits is often highly effective for preventing and treating a wide variety of illnesses and symptoms, especially when paired with appropriate supplements and other natural substances. This basic yet intricate knowledge is supported by scientific research and clinical experience that is reinforced by new studies every year. As described in Nutritional Medicine by Alan R. Gaby, M.D., unlike drug-based medical therapies that often trade negative side effects for symptom relief (e.g., osteoporosis in exchange for pain relief), nutritional medicine almost never causes serious adverse effects. To the contrary, nutritional therapies often produce positive side effects, such as “more energy, better mood, fewer cravings, better mental concentration, and less aches and pains.” To begin unraveling the intricacies of nutritional medicine, read on for an excerpt directly from Dr. Gaby’s book that provides an introduction to the practice of nutritional medicine and the synergistic effects of nutritional treatments. You can also attend CME accredited lectures on Nutritional Medicine taught by Dr. Gaby himself at the Part II and Part III Courses.

NOTE:  The information in this post has been excerpted from Part 1 of the textbook:
Gaby AR. Nutritional Medicine, 2011 (

Part 1 of Nutritional Medicine: Overview


Why Nutritional Medicine?

Scientific research and clinical experience have shown that dietary modifications and administration of nutrients and other natural substances are frequently effective for preventing and treating a wide range of symptoms and illnesses. Moreover, when properly administered, nutritional therapy has an excellent safety profile and almost never causes serious side effects. The nutritional approach to preventing and treating disease rarely subjects patients to the unpleasant trade-offs inherent in many drug treatments, such as statin-induced myalgia in exchange for a lower risk of having a heart attack; beta blocker-induced loss of joie de vivre in exchange for better control of heart failure; or glucocorticoid-induced osteoporosis in exchange for relief of arthritic pain. To the contrary, many of the “side effects” reported by patients who follow a nutritional program are positive, such as more energy, better mood, fewer cravings, better mental concentration, and less aches and pains.

The Practice of Nutritional Medicine

The practice of nutritional medicine includes several main components, the relative importance of which varies from one patient to another. For most patients, nutritional therapy starts with “cleaning up the diet” by emphasizing a wide variety of whole, unprocessed foods and minimizing intake of refined sugars, other refined carbohydrates, trans fatty acids, food additives, and other undesirable constituents of a typical Western diet. Restricting the use of salt, caffeine, and alcohol is also important for some individuals. In addition, emphasizing cooking methods that minimize the formation of potentially toxic compounds (such as cholesterol oxides, lipid peroxides, and advanced glycation end products) may be beneficial. Nutritional therapy also includes the use of a wide array of vitamins, minerals, amino acids, herbs, and other naturally occurring compounds, individualized according to the patient’s needs. This “natural pharmacopoeia” stands alongside the conventional pharmacopoeia of prescription and over-the-counter drugs. Depending on the clinical situation, these natural substances can be used as an adjunct or alternative to conventional medicine.

Hypoglycemia / Allergy / Hypothyroidism / Candida

In my experience, four distinct but overlapping metabolic/endocrine/immunological disorders frequently play a role in the pathogenesis of a number of chronic health conditions. Identification and appropriate treatment of these disorders is important for the successful practice of nutritional medicine. The first disorder, reactive hypoglycemia, is characterized by abnormalities of blood glucose regulation, as well as other accompanying metabolic and endocrine disturbances. Treatment of reactive hypoglycemia includes avoiding refined sugar, other carbohydrates, caffeine, and alcohol; eating small, frequent meals; and supplementing with vitamins, minerals, and other natural substances that aid in blood glucose regulation. The second common disorder is hidden food allergy. In many cases, identifying and avoiding allergenic foods can play a key role in restoring health. In many cases, identifying and avoiding allergenic foods can play a key role in restoring health. Third, a substantial minority of patients appears to have subtle hypothyroidism, despite the presence of normal laboratory tests for thyroid function. These patients benefit from treatment with low doses of thyroid hormone. Fourth is a clinical syndrome that has been called candidiasis or Candida-related complex. This syndrome is characterized by an overgrowth of, or hypersensitivity to Candida albicans. Symptoms overlap with those caused by reactive hypoglycemia, food allergy, and hypothyroidism. Treatment includes antifungal medication and dietary modifications similar to those used for reactive hypoglycemia and food allergy. Hypothyroidism and Candida-related complex are beyond the scope of this chapter.

Individualizing Treatment

Nutritional medicine is highly individualized, and effective treatment varies from one patient to another. For example, some patients with chronic fatigue respond best to dietary modifications such as avoiding refined sugar and eating 6 small meals per day, or identifying and avoiding allergenic foods. In other cases, the most effective treatment for fatigue is a low dose of thyroid hormone or a specific nutritional supplement, such as potassium magnesium aspartate, iron (to correct iron deficiency), or intramuscular vitamin B12 (even in the absence of vitamin B12 deficiency). Frequently, the best results are achieved with a combination of interventions.

Clinical Assessment

Determining which treatments are most likely to be effective for a particular patient requires a proper medical and dietary history, a good physical examination, and a working knowledge of the nutritional-medicine literature. Laboratory tests are essential in some circumstances (as in diagnosing iron deficiency), but may be of questionable validity or even misleading in other situations (as in identifying hidden food allergies or subtle nutritional deficiencies). In practicing nutritional medicine, I have rarely ordered laboratory tests other than those that might be ordered by a conventional medical doctor.

Additive and Synergistic Effects

A recurring theme in nutritional medicine is that combinations of interventions often have additive or synergistic effects, in that they are more effective than single interventions. For example, combinations of nutrients may be more effective than individual nutrients; the beneficial effects of dietary modifications are often more pronounced when combined with appropriate nutrients, hormones, and other natural substances; and the benefits of nutrients, hormones, and other natural substances are often more pronounced when patients also adhere to appropriate dietary recommendations. A corollary to these observations is that nutrients, hormones, and other natural substances are sometimes effective at lower doses when they are used in combination with other interventions than when they are given singly.

Clinical observations regarding the existence of additive and synergistic effects are supported by both clinical and basic-science research. For example, anemia has been found in some studies to respond better to multiple nutrients than to a single nutrient. The combination of B6 and magnesium was reported to be more effective than either of these treatments alone in the treatment of autism. In addition, the homocysteine-lowering effect of folic acid was enhanced by the addition of vitamin B12.1 In dermatology, vitamin E has been used to increase the therapeutic effect of vitamin A. In healthy volunteers, the combination of vitamin C and vitamin E enhanced parameters of immune function to a greater extent than did either of these nutrients individually.2

In mice with experimentally induced atherosclerosis, combined supplementation with vitamin E and coenzyme Q10 was more anti-atherogenic than was either supplement alone.In isolated rat hearts subjected to ischemia and reperfusion, various hemodynamic and metabolic abnormalities were prevented by simultaneous administration of carnitine and coenzyme Q10, but not by administration by either of these nutrients individually.4

Possible Mechanisms

There are a number of possible mechanisms by which dietary modifications and treatment with natural substances could have additive or synergistic effects. For example, dietary improvements might decrease inflammation and oxidative stress, thereby allowing nutritional supplements to be used for processes other than mounting an inflammatory response and quenching free radicals. In addition, certain nutrients enhance the absorption of tissue uptake of other nutrients. For example, vitamin C increases iron absorption and magnesium promotes the uptake of potassium from serum into cells. Some nutrients inhibit the degradation of other nutrients (e.g., flavonoids decrease vitamin C requirements by preventing the oxidation of vitamin C).5 6 Furthermore, certain nutrients may relieve biochemical “bottlenecks” by activating parallel pathways. For example, the conversion of homocysteine to methionine proceeds largely through a folate-dependent pathway, but it may also proceed through a separate pathway that requires betaine. Similarly, multiple biochemical pathways exist to detoxify xenobiotic chemicals, bacterial toxins, and endogenous metabolites.

Synergy and the Art of Nutritional Medicine

Because multiple nutritional interventions are often more effective than a single treatment, practitioners may be tempted to “throw everything but the kitchen sink” at various medical problems. However, nutritional “polypharmacy” is not without potential drawbacks, including high cost to the patient, increased time and effort involved in following the complex treatment regimens, and the possibility that ingesting numerous tablets and capsules will cause gastrointestinal or other side effects.

The art of nutritional medicine includes being able to identify which dietary modifications and supplements are most likely to be beneficial for a particular patient, and which interventions are more likely to be ineffective or unnecessary. As with other healthcare disciplines, mastering the art of nutritional medicine requires education, contemplation, and practice. According to one of my mentors in medical school, Dr. Theodore Woodward, the better trained you are, the fewer tests you will need to perform and the fewer medications you will need to prescribe. That principle also applies to nutritional medicine.


  1. Bronstrop A, Hages M, Prinz-Langenohl R, Pietrzik K. Effects of folic acid and combinations of folic acid and vitamin B-12 on plasma homocysteine concentrations in healthy, young women. Am J Clin Nutr 1998;68:1104-1110.
  2. Jeng KCG, Yang CS, Siu WY, et al. Supplementation with vitamins C and E enhances cytokine production by peripheral blood mononuclear cells in healthy adults. Am J Clin Nutr 1996;64:960-965.
  3. Thomas SR, Leichtweis SB, Pettersson K, et al. Dietary cosupplementation with vitamin E and coenzyme Q10 inhibits atherosclerosis in apolipoprotein E gene knockout mice. Arterioscler Thromb Vasc Biol 2001;21:585-593.
  4. Bertelli A, Ronca F, Ronca G, et al. L-carnitine and coenzyme Q10 protective action against ischaemia and reperfusion of working rat heart. Drugs Exp Clin Res 1992;18:431-436.
  5. Crampton EW, Lloyd LE. Quantitative estimation of effect of rutin on biological potency of vitamin C. Fed Proc 1950;9:355-356.
  6. Clemetson CAB, Andersen L. Plant polyphenols as antioxidants for ascorbic acid. Ann N Y Acad Sci 1966;136:341-376.


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