What Is a Medical Food?

Question

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.
References

1. Food and Drug Administration. Compliance program
   guidance manual. Program 7321.002. Medical foods program -- import and
   domestic. Revised September 2008. Available at: http://www.fda.gov/downloads/
   Food/GuidanceComplianceRegulatoryInformation/ComplianceEnforcement/ucm073339.pdf Accessed April 8, 2011.
   
2. US Food and Drug Administration. Food. Guidance for
   industry: frequently asked questions about medical foods. Revised May
   2007. Available at: http://www.fda.gov/Food/GuidanceComplianceRegulatoryInformation/
   GuidanceDocuments/MedicalFoods/ucm054048.htm Accessed April 8, 2011.
   
3. US Department of Health and Human Services. Food and
   Drug Administration. 21 CFR Ch. 1. Regulation of medical foods. Advance
   notice of proposed rulemaking. Fed Regist. 1996;61:60661-60671.
   
4. Ross S. Functional foods: the Food and Drug
   Administration perspective. Am J Clin Nutr. 2000;71(suppl):1735S-1738S;
   discussion 1739S-42S.
   
5. Federal Trade Commission. Dannon agrees to drop
   exaggerated health claims for Activia yogurt and DanActive dairy drink.
   Released December 12, 2010. Available at: http://www.ftc.gov/opa/2010/12/dannon.shtm Accessed April 8, 2011.