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Supplementing lactating women with flaxseed oil does not increase docosahexaenoic acid in their milk.

Francois CA, Connor SL, Bolewicz LC, Connor WE.  (2003) Am J Clin Nutr. 77(1) 226-33. 

Web URL: View this and related abstracts via PubMed here


BACKGROUND: Flaxseed oil is a rich source of 18:3n-3 (alpha-linolenic acid, or ALA), which is ultimately converted to 22:6n-3 (docosahexaenoic acid, or DHA), a fatty acid important for the development of the infant brain and retina.

OBJECTIVE: The objective of this study was to determine the effect of flaxseed oil supplementation on the breast-milk, plasma, and erythrocyte contents of DHA and other n-3 fatty acids in lactating women. DESIGN: Seven women took 20 g flaxseed oil (10.7 g ALA) daily for 4 wk. Breast-milk and blood samples were collected weekly before, during, and after supplementation and were analyzed for fatty acid composition.

RESULTS: Breast milk, plasma, and erythrocyte ALA increased significantly over time (P < 0.001) and after 2 and 4 wk of supplementation (P < 0.05). Over time, 20:5n-3 (eicosapentaenoic acid, or EPA) increased significantly in breast milk (P = 0.004) and in plasma (P < 0.001). In addition, plasma EPA increased significantly (P < 0.05) after 2 and 4 wk of supplementation. There were significant increases over time in breast-milk 22:5n-3 (docosapentaenoic acid, or DPA) (P < 0.02), plasma DPA (P < 0.001), and erythrocyte DPA (P < 0.01). No significant changes were observed in breast-milk, plasma, or erythrocyte DHA contents after flaxseed oil supplementation.

CONCLUSIONS: Dietary flaxseed oil increased the breast-milk, plasma, and erythrocyte contents of the n-3 fatty acids ALA, EPA, and DPA but had no effect on breast-milk, plasma, or erythrocyte DHA contents.


Supplementing breastfeeding mothers with even very high quantities of flax oil does NOT increase the DHA content of their breastmilk, according to this randomised controlled clinical trial.

This is an extremely important finding - because adequate supplies of the long-chain omega-3 DHA are absolutely essential for normal brain development and function - and yet most mothers eating typical modern, western-type diets have sub-optimal intakes of fish and seafood, which is by far the main dietary source of DHA.

Some longer-chain omega-3 EPA and DHA can (in theory) be made within the body from the shorter chain omega-3 ALA, found in some plant oils - and flax oil is one of the richest sources of ALA.

However, this conversion process is already known to be very slow and inefficient in humans - and depends on genetic as well as numerous diet and lifestyle factors.

This study confirms that for breastfeeding mothers, relying on plant-based sources of omega-3 will not provide optimal breastmilk levels of DHA. 

*Importantly, flax oil also provides more short-chain omega-3 than omega-6 (unlike most vegan sources of omega-3) - and this is important, because these two short-chain 'essential fatty acids' compete for the enzymes needed to convert the short-chain ALA into DHA.