Bioavailability of a-linolenic acid from flaxseed diets as a function of the age of the subject.

Key Findings:

Very little is known with regard to the effects of foods supplemented with ground flaxseed or flaxseed oil in people over 45 years of age. In this study, the effects of ALA (6 g) in the form of milled flaxseed or flaxseed oil was assessed to identify any differences in the responses of the two aged groups to the two different dietary options of flaxseed. There were no adverse side effects reported in any of the groups during this study. This would suggest that age is not a concern when administering up to 30 g of ground flaxseed or 6 g of flaxseed oil to populations within this age range (18–69 years). The data show that the age of the subject is not an important modulatory factor in influencing circulating levels of ALA. Age did note alter the conversion of ALA to EPA. Age does not appear to influence the appearance of adverse side effects either.

ABSTRACT:

Background: Dietary flaxseed may have beneficial cardiovascular effects. An aged population has a higher incidence of cardiovascular disease, but they may react differently to flaxseed in the diet. Objective: To investigate the response, over a period of 4 weeks, of subjects aged 18–29 or 45–69 years to a diet containing the same amount of a-linolenic acid (ALA) (6 g) introduced in the form of ground flaxseed (30 g) or flaxseed oil. Results: All subjects who received flaxseed oil showed a significant increase in plasma ALA and eicosapentaenoic acid (EPA) concentrations over the course of this study. Subjects who received ground flaxseed in the 18–29-year-old group showed a statistically significant increase in their plasma ALA levels, and although there was a trend in the same direction for the 45–69 year-old subjects, this did not achieve statistical significance. The diets induced no major changes in platelet aggregation, plasma total cholesterol, low-density lipoprotein or high-density lipoprotein cholesterol levels in any of the groups. Younger subjects showed a decrease in triglyceride (TG) values compared with older subjects. There were no significant side effects that caused compliancy issues. Conclusion: Subject age does not seem to be a major determining factor in influencing ALA absorption from a flaxseed supplemented diet nor in the metabolism of ALA to EPA in the groups fed flaxseed oil. Concerns about side effects in older subjects administered a higher fiber load in a flaxseed-supplemented diet are not justified. However, younger but not older subjects showed a beneficial decrease in circulating TGs due to flaxseed supplementation.