The participants took 812 milligrams of curcumin or a placebo daily for 1 week at low altitude and 6 weeks at high altitude (3,000 meters).

After 1 week at low altitude, curcumin increased hemoglobin and hematocrit more than the placebo, but after 6 weeks at high altitude, hemoglobin (171 vs. 176 g/L) and hematocrit (47.6% vs. 49.0%) were lower than with the placebo. At this point, diastolic blood pressure was also lower (68 vs. 73 mmHg) and creatinine was higher (101 vs. 95 μmol/L). Acute mountain sickness scores, BMI, and weight were the same in both groups.

A spice for mountain hikers: Can curcumin help your body adjust to high altitude? Original paper