The extent of a focal tendon abnormality was intrasubstance in none (0%) of 16 patients with full-thickness tears, one (20%) of five patients with bursal surface partial-thickness tears, two (20%) of 10 patients with articular surface partial-thickness tears, and two (15%) of 13 patients with tendons without tear.
1 Adequate Intake (AI), where no RDA has been established, but the amount established is somewhat less firmly believed to be adequate for everyone in the demographic group.  Tolerable upper intake levels (UL), to caution against excessive intake of nutrients (like vitamin A) that can be harmful in large amounts.
Linus Pauling Institute Recommendation The optimum intake of niacin for health promotion and chronic disease prevention is not yet known. The RDA (16 mg NE/day for men and 14 mg NE/day for women) is easily obtainable in a varied diet and should prevent deficiency in most people.