The research behind
what we say.

The research behind this figure comes from US clinical trial data. A research summary published in 2026 states that Black Americans make up around 13% of the US population but less than 5% of clinical trial participants.

Representation also varies considerably between different areas of medicine.

We need to know who the findings apply to.

When research includes a narrow group of people, there is less evidence about how well the findings apply to people who were not well represented.

That does not automatically mean a medicine or treatment will work differently. It means there is less evidence to know for sure.

Important differences can be missed.

People can respond differently to medicines or experience health conditions differently for many reasons, including age, sex, genetics, environment and other health factors.

If some groups are not studied well enough, differences that matter may be harder to spot.

Better representation builds better evidence.

Including a wider range of people gives researchers a better chance of understanding what is shared across populations and where meaningful differences may exist.

That is why one of the questions we ask when looking at health research is:

Who was actually included in the research?

The less than 5% figure comes from US clinical trial research. It should not be taken to mean that Black participation is below 5% in every study, every area of medicine or every country.

Better representation also does not mean assuming that racial groups are biologically different.

The body can make vitamin D when skin is exposed to sunlight.

People with a darker complexion generally have more melanin, the pigment that gives skin its colour. This can reduce how much vitamin D the skin makes from sunlight.

UK Government guidance identifies people with what it describes as "darker skin", including people from African and African Caribbean backgrounds, as being at greater risk of low vitamin D levels.

The guidance says people with what it describes as "dark skin" should consider taking 10 micrograms of vitamin D every day throughout the year.

Having more melanated skin does not mean someone is automatically low in vitamin D.

Time outdoors, diet, clothing, age, season and other factors can all make a difference.

Melanin is part of the picture rather than the only factor.

Having more melanated skin does not mean someone is automatically low in vitamin D.

Time outdoors, diet, clothing, age, season and other factors can all make a difference.

Melanin is part of the picture rather than the only factor.

Type 2 diabetes happens when blood sugar levels become too high because the body does not make enough insulin or cannot use it properly. Insulin helps control the amount of sugar in the blood.

In the UK, people from Black African and African Caribbean backgrounds have a higher risk of developing type 2 diabetes. Diabetes UK says type 2 diabetes is two to four times more likely among people of African Caribbean or Black African descent. The increased risk also starts at a younger age. Diabetes UK says the risk begins to rise from around age 25 for these groups, compared with age 40 for White people.

A 2026 study of almost 340,000 people in South London also found a much higher risk among Black African and Black Caribbean groups compared with White British people.

Type 2 diabetes can develop without obvious signs and may go undetected for years.

Over time, high blood sugar can cause serious problems affecting the heart, eyes, kidneys and feet.

A higher risk from a younger age makes knowing your own risk and getting checked when appropriate particularly important.

There is no single explanation for the higher risk. Family history, genetics, diet, physical activity, weight, income, environment, access to healthcare and other factors may all play a part.

The higher risk remained in the 2026 study even after researchers took several other factors into account, showing there is still more to understand.

A higher risk across a population does not tell us what will happen to one individual.

Evolution happens over many generations. When an inherited trait helps people survive in a particular environment, those people are more likely to live long enough to pass that trait to their children. Over time, the trait can become more common.

Sickle cell is one of the clearest examples.

Malaria has historically been widespread across many parts of Africa, especially West and Central Africa. These are also areas where the sickle cell gene became particularly common.

People who inherit one copy of the sickle cell gene are known as carriers, or as having sickle cell trait. They do not usually have sickle cell disease.

Research has shown that carrying one copy can provide significant protection against severe malaria.

In places where malaria was widespread, this gave carriers a survival advantage. Over many generations, they were more likely to survive and pass the gene to their children.

This helps explain why sickle cell trait became particularly common among people with ancestry from West and Central Africa, as well as other parts of Africa where malaria has long been common.

In the UK, sickle cell disease is most commonly seen in people from African and Caribbean backgrounds. But the reason is not simply that they are Black.

It is connected to where their ancestors came from and the long history of malaria in those regions.

The sickle cell gene is also found in people whose family roots are in parts of the Mediterranean, Middle East and South Asia.

Sickle cell shows how environment can shape human genetics over generations, and why ancestry can sometimes tell us more than race alone.

Someone's skin colour or racial identity cannot tell you whether they carry the sickle cell gene.

Not every Black person carries it, and people who do not identify as Black can carry it too.

A blood test is needed to know.

Research using data from England estimated that approximately 1 in 4 Black men will be diagnosed with prostate cancer during their lifetime, compared with approximately 1 in 8 White men.

The study's best estimates were 29.3% for Black men and 13.3% for White men.

That is roughly double the lifetime risk.

The study was published in 2015 and used prostate cancer data from England collected between 2008 and 2010.

The higher risk among Black men is well recognised, but important questions about prostate cancer screening remain unanswered.

In March 2026, the UK National Screening Committee decided there was still not enough evidence to recommend regular screening specifically for Black men.

Then, in June 2026, the UK Government announced more than £20 million for prostate cancer research and treatment, including up to £18 million to expand the TRANSFORM screening study.

If the first stage is successful, all eligible Black men aged 45 to 71 in the UK will be invited to take part in the second stage, provided they have not had a PSA blood test or prostate MRI scan in the previous five years.

The aim is to build the evidence needed to work out the best way to screen Black men for prostate cancer.

This is a current example of why representation in research matters.

We still do not fully understand why Black men face a higher risk of prostate cancer.

Genetics and ancestry may play a part, alongside environment, healthcare and other factors.

The 1 in 4 figure is also based on older data, which is why the date and source should be shown alongside it.

There is still not enough evidence to say that regular screening specifically for Black men would definitely do more good than harm. TRANSFORM is designed to help answer that question.