Supplements with water soluble vitamins or minerals can be Rapid Fast Keto Boost risky if taken in excess, over time. For example, taking extra vitamin B6 has been suggested to help relieve premenstrual tension. Yet there's limited evidence to support large doses for relief of premenstrual syndrome (PMS). Many women have viewed large vitamin B6 doses as harmless, since they are water-soluble. Instead, they may cause irreversible nerve damage when taken in very large doses above the Tolerable Upper Intake Level 500 to 5,000 mg per day.