The width of the red blood cell volume distribution is a parameter that reflects the heterogeneity of the red blood cell volume size, often as a coefficient of variation of the measured red blood cell volume size. It is a parameter that reflects the heterogeneity of the volume of peripheral blood erythrocytes obtained by hematology analyzer measurements. In short, it is an objective indicator of the heterogeneity of red blood cell size. The morphological classification of anemia is generally performed by two parameters, RDW and MCV. Increased red blood cell volume can be prevented and alleviated by diet. It is advisable to eat iron-rich foods; vitamin-rich foods; and foods that promote iron absorption. The following foods are recommended to be eaten in moderation: 1. Pig’s blood Pig’s blood is a food rich in iron to improve iron for patients with iron deficiency anemia. It is recommended that 200-300 grams per day is appropriate. 2, oranges Oranges are rich in vitamin C, which can promote the absorption of iron. It is recommended to have 200-300 grams per day. 3, carp Carp is rich in iron, calcium, zinc and other trace elements. It is recommended to have 200-300 grams per day. Patients with increased red blood cell volume should not eat spicy and stimulating food; stimulating drinks; oily food. The following foods are best eaten sparingly or not: 1, chili pepper is stimulating spicy food, easy to stimulate the gastrointestinal mucosa leading to gastrointestinal congestion, swelling, accelerating intestinal peristalsis, is not conducive to the absorption of iron. Try to avoid. 2, strong tea Strong tea contains caffeine, which has the adverse effect of inhibiting the absorption of iron. Try to avoid drinking. 3, fatty meat contains high fat, which is not conducive to the absorption of trace elements. It is recommended to have no more than 300 grams a week.