Gayle Nicholas Scott, PharmD


June 13, 2011


What is the difference between a medical food, a dietary supplement, and a functional food?

Response from Gayle Nicholas Scott, PharmD
Assistant Professor, Eastern Virginia Medical School, Norfolk, Virginia; Clinical Pharmacist, Chesapeake Regional Medical Center, Chesapeake, Virginia

Prior to 1972, medical foods were primarily formulas designed for the unique nutritional needs of patients with inherited metabolic disorders. These products were regulated as drugs, usually as orphan products. In 1972, the US Food and Drug Administration (FDA) created the classification "medical food" to enhance product development and availability. In the nearly 4 decades since this classification change, products marketed as medical foods have strayed widely from the original narrow use in rare metabolic conditions.[1]

The FDA specifies that medical foods are foods specifically formulated for dietary management of diseases or conditions with distinctive nutritional needs that cannot be met by diet alone. Generally, a product must meet the following criteria to be labeled a "medical food"[1,2]:

  • A specific formulation (as opposed to a naturally occurring foodstuff in its natural state) for oral or tube feeding;

  • Labeled for the dietary management of a specific medical disorder, disease, or condition with distinctive nutritional requirements;

  • Intended for use under medical supervision; and

  • Intended only for a patient receiving active and ongoing medical supervision for a condition requiring medical care on a recurring basis so that instructions on the use of the medical food can be provided.

Think of medical foods as hybrids of prescription drugs and dietary supplements, more closely resembling dietary supplements in terms of regulation. Packaging for medical foods is similar to prescription products with package inserts, National Drug Code (NDC) numbers, and usually "Rx only" on the labels. However, like dietary supplements, medical foods have not been evaluated for safety or efficacy, and the FDA does not require approval before marketing. "Caution: Federal law prohibits dispensing without prescription" is not required on product labeling. The FDA specifies only that these products are for use with medical supervision[1]; however, a medical food manufacturer may market a product to be dispensed only on physician request.[3]

Unlike dietary supplements, medical foods can be labeled for medical conditions such as Alzheimer disease. Dietary supplements must be labeled for so-called "structure and function claims" and cannot make claims to treat or prevent disease.[4] For example, ginkgo may be labeled "supports memory function" but not "for treatment of dementia." A drug or medical food could be labeled "for treatment of dementia associated with Alzheimer disease."

Medical foods that more closely align with the FDA's historic intent are infant formulas such as Phenyl-Free® 1,aphenylalanine-free formula for babies with phenylketonuria, and Ketonex®-1, a branched-chain amino acid-free formula for babies with maple syrup urine disease -- both rare disorders.

Some manufacturers use the loopholes in the medical foods law to market products for disease indication claims that would not be allowed if marketed as dietary supplements. The following are examples of medical foods:

  • Axona® (caprylic triglyceride) is marketed as for dietary management of Alzheimer disease. Caprylic triglyceride is a medium-chain triglyceride found in coconut oil.

  • Limbrel® (flavocoxid™) is marketed for osteoarthritis. Flavocoxid, which sounds remarkably similar to cyclooxygenase (COX)-2 inhibitors such as celecoxib, is a proprietary blend of flavonoids such as baicalin and catechin.

  • Foltx® (folic acid 2.5 mg, pyridoxine 25 mg, cyanocobalamin 2 mg) is marketed for hyperhomocysteinemia, which has been linked to cardiovascular disease.

In terms of drug interactions, adverse effects, and safety, credible research about medical foods is similar to dietary supplements. Manufacturers are not required to prove efficacy or safety before marketing medical foods or dietary supplements. Explain to patients who want to try a medical food that these products have not been evaluated by the FDA, despite the trappings of prescription drugs.

Finally, "functional foods" is simply a lay term, like "nutraceutical." The FDA has no formal definition for functional foods but does regulate safety and labeling as it does for all food products.[4]

Functional foods are foods marketed for purposes other than nourishment. For example, Activia® is a probiotic yogurt marketed to help "regulate your digestive system." It contains a subspecies strain of Bifidobacterium animalis, which is marketed as Bifidus Regularis®. Another example is DanActive® dairy drink that contains a strain of Lactobacillus casei marketed as L casei immunitas® and is labeled to help "support your immune system."

The Federal Trade Commission recently charged Dannon with deceptive advertising. Dannon agreed to drop claims that allegedly exaggerated the health benefits of Activia (relieves irregularity) and DanActive (protects against cold and flu).[5]

For products marketed as medical foods for common indications, clinicians should advise patients that these products are like dietary supplements in terms of FDA oversight. Safety and efficacy are unproven. Functional foods, which are undefined by the FDA, are simply products of marketing strategy. Like dietary supplements, functional foods are not required to undergo safety and efficacy testing prior to marketing.


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