Haemoglobin and iron

Find everything you need to know about how haemoglobin and iron affects blood donation.

What is haemoglobin?

Haemoglobin, or 'Hb', is a protein found in the red blood cells that carries oxygen around your body and gives blood its red colour.

Haemoglobin levels vary from person to person. Men usually have higher levels than women.

We set a high 'cut-off' level because we want to be sure that your haemoglobin will not drop below normal after you have donated.

To ensure your wellbeing we need your Hb to be at least 125g/l for women and 135g/l for men prior to donation.

Why iron is important

Iron is very important because it helps your body to make haemoglobin. You give away a lot of iron when you donate blood.

Our video explains how to boost your iron levels before and after you donate

Video transcript

Fit to donate - Iron in your diet. Top tips to boost your red blood cells naturally.

Iron is an important building block of blood. Our bodies don't make it so we need to eat it every day.

Here are some of the best foods to help build up your red blood cells and improve your health and wellbeing. Keep watching - some of them might surprise you.

Meat, chicken and oily fish contain a high amount of iron. This type of iron is easiest for our bodies to make healthy red blood cells.

Nuts, seeds and dried fruits such as apricots are another good source of iron.

Include budget friendly pulses in your diet such as beans, lentils and chickpeas.

If you use tofu as a plant-based protein, you'll be pleased to know it's also packed with iron. And it's true what they say, eat your greens.

Good news for chocolate lovers. Dark chocolate contains up to 11 milligrams of iron per 100 grams.

Vitamin C can help your body absorb iron. Good sources of vitamin C include citrus fruits, sweet peppers, strawberries, broccoli and brussels sprouts. Try and include these in your meals.

Wait! Avoid tea and coffee an hour before and an hour after meals. They contain tannins which stop you absorbing iron from your meals.

Following these tips at mealtimes can help you get the most out of your meals. You'll boost your iron levels, build your red blood cells and arrive at your appointment fit to donate.

Do something amazing. Give blood. Download our app NHS Give Blood or call us on 0300 123 23 23.

Boosting your iron levels

You can boost iron levels by eating a well-balanced diet.

Although iron from non-meat sources is more difficult for the body to absorb, people following a well-balanced vegetarian or vegan diet should get enough iron.

Every day, try to eat three portions of food in this list which are good sources of iron:

lean red meat, turkey and chicken
fish - including mackerel, sardines, salmon, pilchards and shellfish
eggs
breakfast cereals - some cereals are fortified with iron
pulses and beans - in particular baked beans, chickpeas and lentils
nuts (including peanut butter)
brown rice
tofu
bread - especially wholemeal or brown breads
leafy green vegetables – especially curly kale, watercress, broccoli and spinach
dried fruit - in particular apricots, raisins and prunes

Improve how well iron is absorbed by the body

Vitamin C can help your body to absorb more iron. To get the most from the food you eat, have vitamin C rich foods with meals.

Good sources of vitamin C includes fresh fruits and vegetables for example:

Citrus fruits – oranges or fresh orange juice
Strawberries
Kiwi
Sweet peppers
Brussel sprouts
Broccoli

Avoid drinking tea and coffee for an hour before and after meals. These drinks may prevent you absorbing iron from your food.

How we test your haemoglobin

Before donating blood, plasma or platelets, we check your haemoglobin level to make sure it is high enough for you to donate. It is helpful to be well hydrated and have warm hands before the test.

Your test is done in a private health screening area. Here’s how it works:

A drop of blood is taken from your finger using our finger prick test.
The sample is analysed to check your haemoglobin level is high enough for you to donate.
Occasionally we may need to run another test using different equipment. This involves doing a second finger prick and will give a more accurate measurement of your haemoglobin.

The result helps us decide if you can give blood or if you need to wait some time before returning to donate.

If your haemoglobin is too low to donate, we'll ask you to wait at least 3 months before your next donation. This is to allow your haemoglobin to reach a higher level.

Before you leave your appointment, we will discuss how you can improve your haemoglobin level and give you an advice leaflet to take home.

Why haemoglobin levels might be too low to donate

There are three common reasons:

Variation between people – some of us just normally have a lower level than others.
Iron – we all need iron to make haemoglobin. If your iron stores are low, the haemoglobin may fall below normal (or below the donation level).
Testing procedure – while we take great care with our test on the session, occasionally it underestimates the amount of haemoglobin in the blood.

Further information

If you are worried or require further information, call our donor helpline on 0300 123 23 23.