http://www.sugar-and-sweetener-guide.com/blackstrap-molasses.html
Like sugar, it is harmful to teeth and calorie rich. It has a high glycemic index and is not suitable for diabetics. Some grades are sulfered, meaning sulfer dioxide is added as a preservative.
In addition it can contain up to 20% free fructose, and this is in addition to the sucrose content. Therefore they should be counted as part of the refined sugar in the diet and taken in moderation. (As should fruit juices and honey).
Although often sold in health food shops it is really a form of refined sugar, it does not exist in nature. It contains no fiber, is almost pure carbohydrate and is high glycemic. Moderation is the key word, a spoon or two per day substituting for other refined sugars. Cannot be considered a health food, but has benefit in small quantities.