If you regularly donate blood then it is important to ensure that you supply your body with all the nutrients it needs. Vitamins such as B12, folic acid, and B6, as well as minerals such as iron are vital for blood formation. A deficiency of any of these nutrients could result in your body being unable to restore the blood lost during donation. However, there is a study showing that blood donation has no influence on these values. This is due to the fact that blood loss from donating is too minor to have an effect. Additionally researchers believe that regularly donating helps increase awareness of a healthy diet, which then minimises the risk of deficiency.
Nevertheless researchers suggest periodically testing vitamin levels as the trend of high calorie and low vitamin food increases the risk of deficiences. However there are not many studies on this topic, which is why there are no clear statements available. To compensate for any deficiency caused by donating blood we recommend either consuming more nutrient-dense foods or taking appropriate supplements. In conclusion it appears that a blood donation should not have any influence on your test result. However, we still advise you to check your blood levels regularly in order to be able to detect and counteract a deficiency early.