Molasses is a byproduct of sugar production from sugarcane (or sugar beets). It consists of the thick liquid remaining after the sucrose has crystallized out. Blackstrap molasses, which is the remnant after the third boiling of the sugar syrup, is a concentrated form of cane molasses. Molasses is a good dietary source of iron, calcium, copper, magnesium and manganese, and also contains some vitamin B6 and selenium. Molasses has been shown to have antioxidant properties. The major phenolic compounds in molasses are syringic acid, ferulic acid, vanillic acid and p-hydroxybenzaldehyde.
Breast cancer-related effects of consuming molasses
Syringic acid has been found to inhibit the growth of breast cancer cells in the laboratory. While copper is a vital nutrient, high levels of copper in the blood have been found to be associated with higher risk of breast cancer. Copper has also been shown to promote angiogenesis in existing cancers. No population studies have evaluated any potential associations between molasses consumption and risk of breast cancer.
Bottom line: Blackstrap molasses has been promoted as a health food based on its nutrient contents, including as a cancer treatment in some traditions. However, based on the available evidence, it would appear unhelpful to breast cancer patients, survivors and those at high risk of breast cancer to regularly consume molasses. Honey is a better choice as a sugar substitute.
Blackstrap molasses has moderately high glycemic index, not much lower than table sugar. Unsulphured molasses is a better choice than sulphured molasses since it is made from the juice of fully-ripened cane and has a more desirable flavor.
Note that while we are continually searching for new evidence specifically concerning this food, there is not much interest in it among researchers, so few studies are available.