Medical foods for Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative condition associated with cognitive loss, behavioural changes, functional ability decline and caregiver burden. Given the worldwide public health impact of AD, novel interventions to reduce suffering experienced by AD patients need to be developed. Foods may offer a mechanism for intervention complementary to drugs, devices, biologicals and vaccines. Apart from foods with health claims (including dietary supplements), medical foods are also being explored as an intervention option. The purpose of this article is to describe how medical foods may complement other interventions for AD patients by: (i) defining what a medical food is; (ii) discussing whether AD is a condition amenable to medical food intervention; (iii) reviewing current clinical trial data on medical foods used in participants with AD; and (iv) highlighting steps needed to establish a more comprehensive framework for developing medical foods for AD. While medical foods may be defined differently in other countries, the US Orphan Drug Act of 1998 defined a medical food as a food formulated for enteral intake, taken under physician supervision, and intended to meet the distinctive nutritional requirements identified for a disease or condition. For AD to be amenable to medical food intervention, it must: (i) result in limited or impaired capacity to ingest, digest, absorb or metabolize ordinary foodstuff or certain nutrients; or (ii) have unique, medically determined nutrient requirements; and (iii) require dietary management that cannot be achieved by modification of the normal diet alone. While these criteria are most likely met in advanced AD, identifying unique nutritional requirements in early AD that cannot be met by normal diet modification requires a better understanding of AD pathophysiology. A PubMed search using the terms 'medical food' and 'Alzheimer', limited to clinical trials published in English with human participants with AD aged >65 years and supplemented by other articles known to meet the inclusion criteria, revealed that only two medical foods, AC-1202 and Souvenaid® with Fortasyn Connect™, have clinical trial results available for discussion. As medical food development for AD is a relatively new endeavour, a window of opportunity exists for all stakeholders to develop a comprehensive framework for assuring that medical food interventions for AD achieve the highest possible scientific and ethical standards to warrant commercialization.