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

January 1, 2009 Human Health and Nutrition Data 0 Comments

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

Year: 2009
Authors: Patenaude, A. Rodriguez-Leyva, D. Edel, A.L. Dibrov, E. Dupasquier, C.M.C. Austria, J.A. Richard, M.N. et. al.
Publication Name: European Journal of Clinical Nutrition
Publication Details: Volume 63; 1123 to 1129.


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. To investigate the response, over a period of 4 weeks, of subjects aged 18 to 29 or 45to 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. 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 to 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 to 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. 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. (Authors abstract)
In experimental work, dietary flaxseed has shown anti-arrhythmic and anti-atherogenic actions.  Before initiating large, expensive clinical work in patient populations, it is important to investigate the differences in the response of older subjects to a diet supplemented with ground flaxseed or flaxseed oil.  It is possible that the absorption of ALA from flaxseed may be very different in more aged populations. In addition, because of the high content of fiber and oil, flaxseed may not be tolerated as well in the gastrointestinal tract of older people in comparison with young individuals. Therefore, the purpose of this study was to examine the differences in responses of younger and older healthy subjects to a diet supplemented with flaxseed. The same amount of ALA (6 g) in the form of milled flaxseed or flaxseed oil was also examined to identify any differences in the responses of the two aged groups to the two different dietary options of flaxseed. The data showed that both age groups effectively absorbed ALA from the flaxseed-supplemented diet when it was presented in an oil form. Significantly higher ALA levels were achieved in the older group. This would show clearly that age is not a limiting factor for the absorption of ALA. However, when ground flaxseed was used, the older subjects did not achieve a statistically significant increase in plasma ALA levels despite achieving, once again, higher ALA levels at the end of the study in comparison with the younger subjects. This appears to be due to slightly higher basal levels of ALA in the older subjects than in the younger subjects. Dietary supplementation with flaxseed oil induced an increase in EPA within 4 weeks in both age groups. Therefore, subject age does not appear to be a limiting factor for conversion of ALA into EPA.  Only modest changes in platelet aggregation in the older subjects who consumed flaxseed oil were detected. 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 to 69 years). In conclusion, the data show that the age of the subject is not an important modulatory factor in influencing circulating levels of ALA.  Age does not appear to influence the appearance of adverse side effects either. However, subject age was an important determining factor in the lowering of TG levels in the blood. (Editors comments)

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