Safety of Graded-Dose of Histidine in Humans

Histidine is an essential amino acid with health benefits that include anti-inflammatory, anti-oxidant, glucoregulatory, and weight management. Because of the extended period of time (>35 days) that is required to deplete body histidine pools in adults, it has not been possible to fully determine histidine requirements. The current expert opinion for histidine intake is 8 and 12 mg/(kg body weight per day), an estimate that was extrapolated from the infant requirement for histidine. The average intake of histidine from a normal adult diet in the U.S., Europe, and Japan was reported between 2.12 and 2.40 g/day with the 99th percentile intake in men at 50-70 years of age consuming 5.20 g/day. The clinical safety of histidine supplementation above the average dietary intake has not been determined. Therefore, this study will utilize graded doses of histidine that are at are moderately above the average intake to identify safety and benefits of histidine in a healthy human population. Further, the clinical safety of histidine supplementation above the average dietary intake has not been determined.The overarching objectives are to 1) measure the safety of histidine supplementation and 2) measure the potential benefits of histidine at doses above the average intake and current recommendation in a healthy adult population. Following the completion and review of a health history questionnaire, vitals, and a biochemical panel, participants will be deemed healthy by a nurse practitioner and able to participate. After baseline measures are obtained, supplements (encapsulated histidine) will be provided at three graded doses (4 g/day, 8 g/day and 12 g/day) a forth dose (16 g/day) will be consumed if no adverse effects are observed at the three graded doses. Each dose will be for 28 days followed by a three week recovery period. At baseline, weeks 2 and 4 of supplement, and recovery a basic biochemical panel, anthropometric, urinary and serum zinc, will be conducted. Additionally, body composition will be conducted at baseline and week 4 of each dose. Changes in dietary intake and physical activity will be measured with 4-day food records and Actigraph activity monitors, respectively. Changes in sleep patterns will be measured with the Pittsburgh sleep questionnaire.

Inclusion criteria

• healthy young males and females aged 21-50 y.

Exclusion criteria

• A body-mass index (BMI) <19.9 kg/m2 or > 29.9 kg/m2
• taking/on immunosuppressive medications or prescription anti-coagulation therapy
• pregnancy
• breastfeeding
• musculoskeletal disorder
• diabetes
• alcoholism (>11 drinks per week for women, >14 drinks per week for men) or other drug addiction
• acute illness
• inability to travel to Cornell University campus
• A blood pressure at or above 140/90
• For individuals desiring to participate in the optional biopsy, a history of a negative or allergic reaction to local anesthetic is an exclusion criteria