---
title: "Blood types — what it does and the numbers"
description: "Eight common groups from the ABO and Rh systems — O+ is the most frequent. What it does, where it is, the figures people look up, and the widely repeated claims that"
url: https://atoneplace.net/body/blood-types/
site: "At One Place"
---

# Blood types

**Blood types: Eight common groups from the ABO and Rh systems — O+ is the most frequent.**

Blood group is determined by antigens on the red cell surface. The ABO system covers A, B, AB and O; the Rh system adds positive or negative depending on the D antigen. Transfusing incompatible blood causes the recipient’s antibodies to attack the donated cells, which can be fatal.

## The numbers

- **Universal red cell donor:** O negative
- **Universal plasma donor:** AB
- **Most common worldwide:** O positive
- **Rarest of the eight:** AB negative
- **Recognised blood group systems:** over 40

## Worth knowing

Distribution varies enormously by population — type B is far more common in parts of Asia than in western Europe, and type O approaches 100% in some indigenous American populations. Beyond ABO and Rh there are more than forty recognised blood group systems; the Bombay phenotype is so rare that those who have it can generally only receive blood from other Bombay donors.

## A common claim that is wrong

The blood type diet has no evidence behind it. A controlled study found the diets produced effects unrelated to the participants’ actual blood groups.

> Structural reference only — this is not medical advice, and individual variation in every figure here is substantial. Anything concerning your own health belongs with a clinician rather than a reference page.

## Common questions

### What does the blood types do?

Blood group is determined by antigens on the red cell surface.

### Blood types — key numbers

Universal red cell donor: O negative. Universal plasma donor: AB. Most common worldwide: O positive. Rarest of the eight: AB negative. Recognised blood group systems: over 40.

### Is it true that…

The blood type diet has no evidence behind it. A controlled study found the diets produced effects unrelated to the participants’ actual blood groups.

## Related pages

- [Blood](https://atoneplace.net/body/blood/)
- [Heart](https://atoneplace.net/body/heart/)
- [Brain](https://atoneplace.net/body/brain/)
- [Bones](https://atoneplace.net/body/bones/)
- [Teeth](https://atoneplace.net/body/teeth/)
- [Liver](https://atoneplace.net/body/liver/)
- [Lungs](https://atoneplace.net/body/lungs/)

## Sources

- World Health Organization — WHO (https://www.who.int/)