Vitamin B6 may be of benefit for the relief of premenstrual symptoms such as cramps, breast tenderness, fluid retention, irritability and mood swings. Features and benefits. High potency sustained release nutritional supplements supply their nutrients gradually over several hours. Convenient one-a-day dosage.The sustained release system used by Blackmores is based on a unique plant gum matrix, using guar gum from the seeds of a legume. The sustained release principle involves the leaching of vitamins and minerals from the tablet `core' as it passes through the gastrointestinal tract.