Trial Information

Studies of Serum PSA to Help Resolve the Current Implication of Alpha-linolenic Acid (ALA) and Prostate Cancer

In addition disturbing news on alpha-linolenic acid (ALA) has recently been reviewed by
Brouwer and colleagues (J Nutr:2004). Their analyses suggests that ALA, as found in canola
oil and other healthy foods, may cause prostate cancer even though there is good evidence
that canola oil will prevent heart disease. This issue urgently needs further research.

In studies largely from the Harvard group, but suggested by additional studies from Uruguay
and Spain, a link has been identified between ALA intake and prostate cancer. The Harvard
studies are cohort studies where groups of approximately 40,000 doctors or health
professionals have been followed up for periods of 10 years and the dietary intakes of ALA
related to the subsequent development of aggressive prostate cancer. It must be stressed
that these are not randomized crossover studies which are the currently accepted gold
standard for evidence-based medicine and regulatory decision making. Nevertheless they
raise concern over the health profile of a fatty acid with a growing reputation for
cardiovascular disease prevention and a component of other healthy foods such as walnuts,
flax, canola and soy.

The same Harvard group identified the deleterious effects on cardiovascular health of trans
fatty acids in their cohort studies and this has resulted in a major effort to remove trans
fatty acids from the food supply. On the other hand their identification of the benefits of
vitamin E in their cohort studies has not been confirmed by subsequent randomized controlled
trials. Although Dr Willett, the senior member of the Harvard group, has drawn surprisingly
little attention to the negative findings with ALA, it remains a sticking point with
regulators in the current debate over the inclusion and use of ALA in the food supply. This
concern has been sufficient for the Natural Health Products Directorate of Health Canada to
ask for a full proposal from us before we start studies on ALA in the prevention of atrial
fibrillation due the apparently negative impact of ALA consumption on prostate cancer.