Article by Professor Salomé de Almeida

What Should We Do with This… Blood?

It often crosses my mind. I have it, you might need it, someone else certainly does...

And what about us? We are responsible for one another. So why not give a little of ourselves, something that runs through our veins? Yes, let’s talk about blood.

Can we donate blood? Why should we? And how does the process work?

Don’t overthink it. Follow this train of thought, and we hope we can convince you.

Professor Salomé de Almeida

A. Blood: What Is It and Why Is It So Important?

For as long as we can remember, we have understood that blood is a precious and essential resource. Blood symbolizes life and accompanies each of us throughout every stage of existence, constantly adapting to help maintain survival and balance within the body.

Today, we know much more about the composition and functions of blood than ever before. Even so, science has not yet been able to fully replace it, and medicine continues to depend on donated blood to save lives.

Blood is made up of different types of cells suspended in a liquid called plasma. Both components have distinct characteristics and functions.

The cellular elements include red blood cells, which are essential for transporting oxygen to tissues; white blood cells, which help defend the body against infections and external threats; and platelets, which play a crucial role in blood clotting and wound healing.

Plasma consists mainly of water, minerals (electrolytes), nutrients, and various molecules such as hormones, antibodies, and proteins. These substances are vital for regulating bodily functions, maintaining balance, transmitting signals, and combating infections and other challenges to health. Blood circulates through an extensive network of blood vessels, delivering these components to every tissue in the body. It also collects waste products from tissues and transports them to the kidneys for elimination through urine. Blood carries oxygen throughout the body and transports carbon dioxide back to the lungs, where it is released.

We have long known that we do not need all of our blood at once. The body continuously renews it, which means we can safely give a small amount from time to time and share it with those who need it.

A single blood donation can help save up to three lives. This is because donated blood is separated into red blood cells, plasma, and platelets, each of which can be used in specific treatments. These components are essential for children and adults with chronic illnesses, patients with anaemia or leukaemia, individuals involved in accidents, those experiencing obstetric complications, and people undergoing surgery.

B. How Does Blood Donation Work?

Donating blood is a simple and safe procedure, but it is also carefully regulated to protect both donors and recipients.

Before donating, each donor undergoes a medical assessment, completes a health and lifestyle questionnaire, and has blood tests performed. These tests identify characteristics such as blood type and screen for infectious diseases.

This screening is important because blood can carry viruses, bacteria, and other disease-causing agents. Testing for transmissible diseases, including AIDS (Acquired Immunodeficiency Syndrome, caused by the Human Immunodeficiency Virus, HIV), hepatitis, syphilis, and others, is mandatory.

The donation process itself takes approximately 30 minutes. After collection, the blood is tested, separated into its components, processed, and stored until needed. If an infection is detected or the blood does not meet safety standards, it is discarded to protect patients and maintain the integrity of the blood supply. Donors are informed whenever necessary.

After donating, individuals are advised to rest for the remainder of the day, avoid smoking for a few hours, and drink plenty of fluids. The body recovers quickly, and healthy individuals with no risk factors may donate blood up to three times per year for women and four times per year for men.

C. Who Can Donate Blood?

Almost convinced? I hope so. However, there are some requirements and limitations.

To donate blood, individuals must be at least 18 years old, weigh more than 50 kg, be in good health, and not be pregnant or breastfeeding. They must not be currently ill or have undergone recent surgery.

Certain situations require medical evaluation, including chronic medication use and specific health conditions. Some diseases, such as cancer, hepatitis B or C, Chagas disease, and Creutzfeldt–Jakob disease, permanently prevent a person from becoming a blood donor.

Certain behaviours are also considered high risk, including the use of injectable drugs and sexual contact with individuals carrying HIV or other sexually transmitted infections, making blood donation unsuitable.

Other circumstances, such as tattoos and body piercings, require temporary deferral. In most cases, donors must wait at least four months before donating blood in order to minimise the risk of infection.

All of these situations are assessed carefully, respectfully, and confidentially. Blood donation is an act of solidarity, it should never be associated with commercial gain or financial compensation. The process must be safe and beneficial for both the donor and the recipient.

D. Myths: You’ve Probably Heard Some of These

It is not always easy to distinguish myths from facts.

One common misconception is that donating blood causes weight gain or weight loss. In reality, the body quickly replaces the donated volume. Another myth is that blood becomes thicker or thinner after donation; this is not true, as the overall composition of blood remains unchanged.

It is also incorrect to assume that being vegetarian or vegan prevents someone from donating blood. What matters is that iron levels, haemoglobin levels, and other relevant health indicators remain within normal ranges.

Please note that international travel may sometimes affect eligibility to donate. For example, travel to regions where malaria, dengue fever, or Zika virus are active may require a waiting period ranging from 28 days to six months before donation is permitted.

If you have questions, a healthcare professional is always the best person to provide accurate guidance.

E. Why Is Blood Donation So Important?

Blood donation is a cornerstone of modern healthcare. Blood components are used in a wide variety of clinical situations, and the procedures for donation, collection, processing, and distribution are carefully regulated worldwide.

The WHO[1] estimates that approximately 118.5 million units of blood are donated globally each year. Around 40% of these donations occur in high-income countries, which represent only about 16% of the world's population.

In many low-income countries, a significant proportion of blood donations come from family members or paid donors, which may increase the risk of transfusion-transmitted infections.

The WHO recommends national blood policies based on voluntary, regular, and safe blood donation. It also promotes maintaining a genetically diverse blood supply to meet the needs of patients with rare and specific blood types.

F. So, What’s Next?

Convinced? We certainly hope so.

Each of us has the opportunity to make a meaningful contribution by donating blood and helping others. Through this simple act, we support medicine in its ongoing mission to save lives and improve health.

In Portugal, blood donation is coordinated by the Portuguese Institute of Blood and Transplantation (IPST). Donations can be made at the Regional Blood and Transplantation Centres in Lisbon, Porto, and Coimbra, at fixed collection sites located within healthcare institutions, and through mobile collection units that travel throughout the country. Information about donation opportunities is widely available and regularly promoted through social media channels.

Donating blood costs almost nothing. And what we receive in return is as big as the world itself!