Docosahexaenoic acid (DHA) is important for proper neurological development of humans and animals. In growing animals, 4 ways exist to meet the DHA requirement of neural tissues: uptake of DHA directly from dietary sources; desaturation and elongation of ALA within the neural tissues; uptake of intermediate ALA derivatives such as DPA after hepatic conversion with further synthesis in neurologic tissues to DHA; and uptake of circulating DHA synthesized in tissues such as liver.

After parturition, maternal milk serves as the sole exogenous source of long-chain PUFA (LC-PUFA) for the newborn. Its fatty acid profile is reflected in the maternal dietary fat intake.

Francois et al. observed the effects of 6 dietary fats, including menhaden oil, on breast milk fatty acids for 6 d after a single fatty meal. In the menhaden oil group, DHA appeared within 6 h after the meal, peaked within 24 h, and remained elevated for up to 3 d.

Francois et al. also conducted a study in which lactating women were supplemented with 20 g flaxseed oil (10.7 g ALA) for 4 wk. Although some enrichment of milk eicosapentaenoic (EPA) and DPA was found, there was no accumulation of DHA. Although unexpected, this finding likely reflects the need for peroxisomal synthesis from DPA which may not occur in mammary tissue.

We have similarly observed that the milk of dogs fed flaxseed oil diets from gestation onward is enriched only in ALA and not EPA or DHA.

The purpose of the present study was thus to determine whether the suckling of ALA-rich milk by puppies results in DHA synthesis. Such a finding would support the capacity of puppies to utilize 18 carbon (n-3) fatty acid precursors in milk to meet their DHA needs and provide an alternate source of this fatty acid for neurologic development and function.

PMID: 16772507

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