The supply of oxygen and metabolism in the body are mainly completed through the red blood cell system. Red blood cells, also called erythrocytes, are the most abundant type of blood cell. Hemoglobin in red blood cells can combine with oxygen in the air, so red blood cells can transport oxygen inhaled into the alveoli to tissues through hemoglobin, while carbon dioxide generated by tissue metabolism is transported back to the lungs through red blood cells and expelled from the body.

Dark tea is rich in tea polysaccharides, which enhance immune function, provide antioxidant effects, scavenge free radicals, protect against radiation damage, protect hematopoietic function, resist blood clotting and thrombosis, and reduce platelet aggregation. Tea polysaccharides also increase fibrinolytic enzyme activity, lower neutral fat, total cholesterol, and low-density lipoprotein cholesterol, improve the suspension stability of blood cells, and slow down erythrocyte sedimentation. Thus, they improve blood circulation, protect the cardiovascular system, and enhance the oxygen-carrying capacity of red blood cells.

Dark tea is rich in protein (about 20% to 30%), as well as minerals such as iron, manganese, and selenium, and various vitamins including folic acid. The main raw materials for the body to produce red blood cells are protein and divalent iron, and appropriate amounts of auxiliary substances such as vitamin B12 and folic acid are also needed to promote the maturation of red blood cells. In addition, vitamins B6, B2, C, E, and trace elements such as copper, manganese, cobalt, and zinc are also required. It can be seen that dark tea provides important nutrients for the generation and maturation of red blood cells.

Modern people have less physical activity and consume more high-fat, high-calorie diets, leading to an increase in metabolic diseases. Regular consumption of dark tea, such as the high-quality dark tea Chan'er fu tea, can help solve a large part of the "sub-health" problem.