Flaxseed and Flaxseed Oil in pregnancy and breastfeeding

What NCCIH says about safety

Don’t eat raw or unripe flaxseeds; they may contain potentially toxic compounds. Limited amounts of flaxseed (especially flaxseed lignan extract or mucilage) or oral flaxseed oil supplements may be safe for use in the short-term (up to 6 months). Higher doses of flaxseed or flaxseed oil supplements may cause uncomfortable digestive symptoms like bloating, fullness, and diarrhea. There are theoretical reasons to suspect that flaxseed or flaxseed oil might interact with other drugs, such as anticoagulant or antiplatelet drugs. If you take any type of medicine, talk with your health care provider before using flaxseed, flaxseed oil, or other herbal products; some herbs and medicines interact in harmful ways. Some studies of the use of flaxseed during pregnancy suggest it is possibly unsafe, but the evidence is not conclusive. Little is known about whether it is safe to use flaxseed while breastfeeding. Little is known about whether it is safe to use flaxseed oil during pregnancy or while breastfeeding.

Quoted in full from NCCIH so nothing is lost in summarising. Where they say “little is known”, that means the studies do not exist — not that the herb is known to be safe, and not that it is known to be harmful.

How much is actually known

Some research of varying quality has studied the use of flaxseed or flaxseed oil supplements for several health purposes in people.

What the research has found

One clinical trial suggests that flaxseed mucilage powder (mixed with water) might support weight loss in adults with overweight or obesity. However, flaxseed lignan extract and flaxseed oil supplements don’t seem to help with weight loss. In pregnant people with gestational diabetes, some research suggests that flaxseed oil supplements containing ALA might improve fasting measures and insulin resistance. More research is needed to study whether flaxseed lignan extract could improve glycemic control or fasting blood glucose in people with type 2 diabetes. It’s unclear whether flaxseed oil supplements could help other people with diabetes, such as those with diabetic foot ulcers. NCCIH recently funded preliminary research to learn more about how flaxseed could affect the gut microbiome and inflammation in the body.

Before you take this

Dose and form change the answer completely. A culinary amount of a spice, a cup of tea, and a concentrated supplement extract are three different things, and most research is done on the last of them.

Supplements are also not regulated like medicines, so strength and purity vary between products. Bring the actual bottle to your midwife, doctor or pharmacist — that conversation is worth more than any page, including this one.