I would start B complex vitamin supplements. I would put 100 to 150 mg B3-niacin - per gallon of drinking water (about 15 mg per pint) . In other words, use the amount of B3 as the guide for how much water per capsule.
But I would use B complex, not just niacin. At the same time if you have plain niacin - not no flush, not timed release - I would start with that.