to flax or not to flax?

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Flax may not be a great dietary source of EPA or DHA...

Journal of the American College of Nutrition, Vol. 27, No. 2, 214-221

(2008)

Published by the American College of Nutrition

<http://www.jacn.org/misc/terms.shtml>

Bioavailability of Alpha-Linolenic Acid in Subjects after Ingestion of

Three Different Forms of Flaxseed

J. Austria, N. , MSc, Mirna N. Chahine, PhD,

L. Edel, MSc, J. Malcolmson, PhD, Chantal M.C. Dupasquier,

MSc and Grant N. Pierce, PhD

Cell Biology Laboratory, Canadian Centre for Agri-food Research in

Health and Medicine, St Boniface Hospital Research Centre, and

Department of Physiology, Faculties of Medicine and Pharmacy, University

of Manitoba (J.A.A., M.N.R., M.N.C., A.L.E., C.M.C.D., G.N.P.)

Canadian International Grain Institute (L.J.M.), Winnipeg, Manitoba,

CANADA

Address correspondence to: Grant N. Pierce, PhD, St. Boniface Hospital

Research Centre, 351 Tache Ave., Winnipeg, Manitoba, R2H 2A6, CANADA.

E-mail: gpierce@...

Background: Dietary flaxseed may have significant health-related

benefits due to its high content of the omega-3 fatty acid,

alpha-linolenic acid (ALA). However, before extensive work can be

undertaken in clinical populations to determine its efficacy, basic

information on ALA bioavailability from flaxseed and the physiological

effects of its ingestion need to be examined.

Objective: The purpose of this study, therefore, was to determine the

bioavailability of ALA when the flaxseed was ingested in the form of

whole seed, milled seed or as flaxseed oil.

Design: The flaxseed components (30 g of seed or 6 g of ALA in the oil)

were baked into muffins for delivery over a 3 month test period in

healthy male and female subjects.

Results: Flaxseed ingestion over a 1 month period resulted in

significant (P = 0.005) increases in plasma ALA levels in the flaxseed

oil and the milled flaxseed supplemented groups. The former group had

significantly (P = 0.004) higher ALA levels than the milled flaxseed

group. The subjects supplemented with whole flaxseed did not achieve a

significant (P > 0.05) increase in plasma ALA levels. An additional two

months of flaxseed ingestion did not achieve significantly higher levels

of plasma ALA in any of the groups. However, no significant increase was

detected in plasma eicosapentaenoic acid (EPA) or docosahexaenoic acid

(DHA) levels in any of the flax-fed groups. There were no changes in

plasma cholesterol or triglycerides or in platelet aggregation at any

time point in any of the groups. Subjects in all of the groups exhibited

some symptoms of gastro-intestinal discomfort during the early stages of

the study but these disappeared in the oil and milled seed groups.

However, compliance was a problem in the whole flaxseed group.

Conclusion: In summary, ingestion of flax oil and milled flaxseed

delivered significant levels of ALA to the plasma whereas whole flaxseed

did not. Whole seed and oil preparations induced adverse

gastrointestinal effects within 4 weeks and these were severe enough to

induce the withdrawal of some subjects from these two groups. No one

withdrew from the group that ingested milled flaxseed and, therefore,

may represent a good form of flaxseed to avoid serious side-effects and

still provide significant increases in ALA to the body.

Key words: omega-3 fatty acid, polyunsaturated fatty acids (PUFA),

platelet aggregation, linseed, cardiovascular disease

S. Kalman PhD, RD, CCRC, FACN

Miami Research Associates

Director, Nutrition & Applied Clinical Research

6141 Sunset Drive #301

Miami, FL. 33143

(fax)

www.miamiresearch.com <http://www.miamiresearch.com>