Summary of Use during Lactation

Flax (Linum usitatissimum) seed provides a nonabsorbable fiber which has been used as a laxative and has also been used topically to treat various skin conditions. Flaxseed oil contains alpha-linolenic acid (ALA), which is partially converted into the omega-3-fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in the body. Flaxseed oil increases the ALA content of breastmilk, but does not increase the DHA content. Maternal intake of preformed DHA, primarily derived from seafood or other marine oils, is required to increase breastmilk DHA content.[1,2] Flaxseed is generally well tolerated in adults, with occasional allergic skin reactions occurring. Very limited data exist on the safety and efficacy of flaxseed oil in nursing mothers or infants. However, supplementation of infant formula with ALA appears to improve the infant's DHA status.[3] Flaxseed used by the nursing mother as a laxative or topical poultice are not expected to adversely affect the breastfed infant. Flaxseed oil can be used during lactation, but is not effective in counteracting a low maternal DHA intake, as in vegetarian or vegan diets. Flax seed is a purported galactogogue,[4] but one study found that it was not effective.

Dietary supplements do not require extensive pre-marketing approval from the U.S. Food and Drug Administration. Manufacturers are responsible to ensure the safety, but do not need to prove the safety and effectiveness of dietary supplements before they are marketed. Dietary supplements may contain multiple ingredients, and differences are often found between labeled and actual ingredients or their amounts. A manufacturer may contract with an independent organization to verify the quality of a product or its ingredients, but that does not certify the safety or effectiveness of a product. Because of the above issues, clinical testing results on one product may not be applicable to other products. More detailed information about dietary supplements is available elsewhere on the LactMed Web site.

Drug Levels

Maternal Levels. Seven nursing women who were 2 to 11 months postpartum were given 4 weeks of supplementation with 20 grams flaxseed oil (10.7 grams of alpha-linolenic acid) daily after a 2-week washout period. The flaxseed oil was given as 1 gram capsules (Spectrum Essentials Veg-Omega 3 Cold Pressed Organic Flax Oil; Spectrum Naturals Inc., Petaluma, CA) in 3 divided doses. Ten breastmilk samples were collected at about the midpoint of nursing. Samples were collected at baseline, after the 2-week washout, weekly during supplementation, and for 4 weeks afterward. The ALA and docosapentaenoic acid (DPA) content of breastmilk increased markedly and EPA increased slightly during supplementation. The ALA content of milk reached a peak of 7.5% of fatty acids at the end of 4 weeks of supplementation and returned to near baseline of 1.9% after as little as one week after supplementation was discontinued. No increase in breastmilk DHA was seen during the study.[5]

Infant Levels. Relevant published information was not found as of the revision date.

Effects in Breastfed Infants

Relevant published information was not found as of the revision date.

Effects on Lactation and Breastmilk

A randomized, blinded trial compared lactation cookies containing oatmeal, brewer’s yeast, flax seeds, and fenugreek (Oatmeal Raisin Milkmakers Lactation Cookie Bites, Munchkin Inc.) were compared to similar cookies with no purported galactogogues (Famous Amos Chocolate Chip Cookies). Subjects were women nursing full-term 2-month-old infants (n = 176) and instructed to eat one bag of cookies daily for 30 days. They pumped their breasts completely with an electric pump at the start and end of the study. The milk production rate was 5.8 mL/hour in control participants and 5.5 mL/hour in the lactation cookie participants, which was not statistically significant difference.[6]

References

1.

Bourre JM. Dietary omega-3 fatty acids for women. Biomed Pharmacother 2007;61:105-12. [PubMed: 17254747]

2.

Brenna JT, Salem N, Jr, Sinclair AJ, et al. Alpha-linolenic acid supplementation and conversion to n-3 long-chain polyunsaturated fatty acids in humans. Prostaglandins Leukot Essent Fatty Acids 2009;80:85-91. [PubMed: 19269799]

3.

Udell T, Gibson RA, Makrides M. The effect of alpha-linolenic acid and linoleic acid on the growth and development of formula-fed infants: A systematic review and meta-analysis of randomized controlled trials. Lipids 2005;40:1-11. [PubMed: 15825825]

4.

Erarslan ZB, Kültür S. Medicinal plants traditionally used to increase breast milk in Turkey: An ethnobotanical review. J Herbal Med 2024;44:100849. doi:10.1016/j.hermed.2024.100849 [CrossRef]

5.

Francois CA, Connor SL, Bolewicz LC, et al. Supplementing lactating women with flaxseed oil does not increase docosahexaenoic acid in their milk. Am J Clin Nutr 2003;77:226-33. [PubMed: 12499346]

6.

Palacios AM, Cardel MI, Parker E, et al. Effectiveness of lactation cookies on human milk production rates: A randomized controlled trial. Am J Clin Nutr 2023;117:1035-42. [PubMed: 36921902]

Substance Name

Flaxseed

Scientific Name

Linum usitatissimum

Drug Class

Breast Feeding

Lactation

Milk, Human

Complementary Therapies

Food

Galactogogues

Laxatives

Oils

Phytotherapy

Plants, Medicinal