Doses used in studies vary, and a specific recommended daily dose is not yet clear.

As whole flaxseed, studies have used dosages ranging from 10 to 60 grams per day. As flaxseed oil, dosages range from 1 to 42 grams per day. Lignan — a phytoestrogen in flaxseed — can be supplemented in capsules with dosages ranging from 100 to 600 milligrams per day.^{[1][2][3][4][5][6][7]}

Currently there is no clear recommendation on the best form of flaxseed supplement to use. Ground flaxseed and flaxseed oil are more readily absorbed than whole flaxseed,^[8] and taking flaxseed in ground form may be more effective for lowering LDL cholesterol levels.^[1][2] High blood pressure might respond best to flaxseed oil,^[9][10] while whole flaxseed had a more significant effect on BMI, weight loss, and waist circumference in one meta-analysis.^[11]

It is important to remember to store ground flaxseed in an airtight container to prevent it from oxidizing. In warmer climates it is advisable to store it in the refrigerator.^[12] Flaxseed oil should be stored in a cool, dark environment, because it can be damaged by both heat and light.^[13]