Abstract: Methods Athletes in a sports training base in Guangdong Province were recruited.All subjects were orally administrated folic acid supplement (1.0 mg/d) for 3 months.Balanced diet was required during the period.Before and after the folic acid intervention for three months, questionnaire survey was conducted to collect information including age, gender, height, weight, education level, disease history, and dietary supplement intake.Dietary survey was conducted over three consecutive days by 24-hour recall method.Average daily intake of energy, carbohydrate, protein, fat, and dietary folic acid were calculated by the obtained dietary data using nutritional calculation software 2,1 designed by Chinese CDC.Plasma levels of inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), and interleukin-1β(IL-1β) were evaluated before and after 3-month folic acid intervention.ResultsA total of 114 athletes were recruited, including 56 males (49.1%) and 58 females (50.9%).Their age was（22.24±4.16）years (mean±SD ) and BMI was 22 70±4 19 After folic acid intervention for three months, the plasma levels of TNF-α(47.92 pg/mL), IL-8 (1.89 pg/mL), and IL-1β(12.3954 (P<0.01).Conclusion Folic acid supplement can decrease the plasma levels of pro-inflammatory cytokines TNF-α, and IL-8, increase the IL-10/TNF-αratio, thus reduce inflammatory levels in athletes undergoing long-term intensive exercise training.