Astaxanthin, a potent antioxidant compound, is well recognized for its beneficial effects to protect from oxidative stress and free radicals. However, the effects of long period of use of astaxanthin on biological parameters, health indicators, and energy intake are still largely unknown. A total of 33 healthy participants aged 21–54 years with body mass index in the range of 18.50−24.90 kg/m2 were enrolled in this randomized controlled trial and were assigned into astaxanthin and placebo groups. The participants in the astaxanthin group received 4 mg of astaxanthin once daily for 12 consecutive weeks. Dietary intakes, as well as blood levels of astaxanthin and biological parameters, were investigated at baseline and week 12. The significant elevation of blood astaxanthin level in the astaxanthin group was notified at week 12. Regarding basic characteristics of blood biochemical parameters, results indicated that the fasting blood glucose, total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol were not significantly different between astaxanthin and placebo groups at week 12. Interestingly, the significant decrease in total energy and carbohydrate intakes of the participants in the astaxanthin group (P < 0.05) was found after 12-week supplementation, compared to the baseline. The findings support the safety of long-term supplementation and reveal potential dietary intake lowering effect of astaxanthin in healthy individuals.