Lignans are compounds found in a variety of plant materials including flaxseed,
pumpkin seed, sesame seed, soybean, broccoli, and some berries. The major lignan in
flaxseed is called secoisolariciresinol diglucoside (SDG). Once ingested, SDG is converted
in the colon into active mammalian lignans, enterodiol, and entero-lactone, which
have shown promise in reducing growth of cancerous tumors, especially hormone-sensitive
ones such as those of the breast, endometrium, and prostate. Known for their hydrogen-donating
antioxidant activity as well as their ability to complex divalent transition metal
cations, lignans are propitious to human health. The extraction methods vary from
simple to complex depending on extraction, separation, fractionation, identification,
and detection of the analytes. Flax lignan is also a source of useful biologically
active components found in plant foods, such as phytochemicals, and it is considered
a functional food. The safety issues in flaxseed are also briefly discussed.