Could your blood type influence what you crave at mealtimes? It’s a question that has intrigued many. The “blood type diet” concept has been around since the late 1990s, gaining traction with bold claims: eat according to your ABO blood group – A, B, AB, or O – and you’ll unlock better health, lower disease risk, and perhaps even extend your life.

Now, a study published in Medicines by researchers in Greece is stirring up the conversation once more.

The study, which involved over 300 healthy blood donors, examined connections between blood type, Rh factor, and dietary preferences. Alcohol, caffeine, fats, vitamins – the researchers tracked it all.

The results? Surprising patterns emerged. Yet, when these findings are set against the wider backdrop of medical evidence, the story becomes much more nuanced.

Let’s unpack what this research means for you. Should you overhaul your diet based on your blood type? Or is this another health fad with more hype than substance?

The Greek Blood Donor Study: A Closer Look

First, some context. This was not a sprawling international trial. It was a pilot study – a first step in exploring a complicated question. Conducted at a hospital blood bank in Naousa, northern Greece, the study recruited 329 regular blood donors. These individuals were already screened for general good health.

Blood types were split into groups: A (141 participants), B (65), O (96), and AB (27). The scientists also recorded each donor’s Rh factor (positive or negative) and whether they smoked.

Each participant gave a detailed account of their dietary habits over three days – including two weekdays and one weekend day. Trained nurses and dietitians helped ensure accuracy. Specialised software then analysed their food diaries for alcohol, caffeine, sugar, fibre, cholesterol, and an array of vitamins and fats.

The aim? To spot any clear links between blood type and what people eat and drink.

Does Blood Type Shape Our Appetites?

Patterns did emerge. Group O donors reported eating more sugar, drinking more alcohol, consuming more caffeine and taking in more vitamin D than those in other groups. Group A individuals showed higher cholesterol and fibre intake and had a notably higher rate of smoking. Group B’s diets leaned towards more fatty foods. Those with AB blood appeared the most moderate in their eating habits.

Rh factor played a role too. Rh-positive donors consumed a little more alcohol, caffeine, cholesterol and vitamins C, D, E and K compared to Rh-negative donors.

Smokers tended to have poorer diets overall – fewer fibres, less vitamin D, and lower healthy fat intake. Non-smokers fared better in these categories.

These trends are fascinating. They suggest that our blood group may slightly nudge our dietary choices. But let’s not leap to conclusions.

What Does Broader Evidence Say?

Major health institutions have weighed in on the blood type diet theory before. According to research from PLoS One, diets rich in plants and low in processed foods do improve heart health markers like cholesterol and blood pressure. However, these benefits are consistent across all blood groups. Your ABO status does not change how much you gain from eating well.

Scientists at global health organisations, including WHO do not recommend using blood type to guide daily food choices. There’s simply not enough evidence that matching your meals to your blood group brings unique benefits.

Yes, certain blood types are linked to increased risk of specific diseases. Non-O groups – especially A – show higher rates of clotting disorders and slightly greater risk for coronary artery disease. Blood group O offers some protection against severe malaria. These links are real but small compared with lifestyle factors like smoking or obesity.

Even the supposed connection between blood type and COVID-19 is now seen as minor. Early studies hinted that group A people were at greater risk for infection or severe illness; subsequent research found these effects were slight and inconsistent.

As for taste preferences? There are hints that ABO antigens may influence taste perception or cravings due to their expression on some sensory cells. Yet the effect is subtle. Most experts agree: genetics play a role in what we like to eat but do not dictate our entire menu.

Is Rh Factor Important for Diet or Allergies?

The Greek study observed differences by Rh status too. Rh-positive donors drank more alcohol and caffeine and took in higher vitamin levels than their Rh-negative counterparts. Some older studies have speculated about Rh-negative individuals having more IgE-mediated allergies, but this is far from settled science.

The NHS and allergy specialists do not routinely consider Rh factor when assessing allergy risk or shaping dietary advice. If you have food allergies or sensitivities, personalised medical guidance remains essential.

Smoking Status is The Real Dietary Divider

One of the clearest findings in both this Greek study and larger research is how smoking affects diet. Smokers tend to consume less fibre and vitamin D and eat fewer healthy fats such as olive oil or nuts. They also often have lower fruit and vegetable intake.

Non-smokers usually follow healthier eating patterns overall. For anyone looking to improve their diet – quitting smoking should be near the top of the list.

Should You Eat for Your Type?

With all this data swirling around, it’s tempting to search for a secret formula based on your blood group. The reality is far less dramatic.

Firstly, the study was observational – it identified correlations rather than cause-and-effect relationships. Just because group O donors drank more alcohol on average does not mean their blood type made them do it.

Secondly, the sample was limited to healthy Greek blood donors following a Mediterranean-influenced diet. Extrapolating these trends to other countries or ethnic groups is risky.

Thirdly, even where blood type links to disease risk exist (such as thrombosis or malaria), lifestyle factors are overwhelmingly more important.

The consensus among experts is clear: focus on proven healthy dietary patterns rather than chasing a genetic ideal tied to ABO or Rh status.

What Should You Do Instead?

If you want to eat better, here’s what the evidence supports:

• Prioritise vegetables, fruits, whole grains, pulses.
• Choose healthy fats: olive oil, nuts, seeds, oily fish.
• Limit salt, added sugars, ultra-processed foods.
• Keep alcohol moderate.
• Avoid smoking.
• Stay physically active.

These principles benefit everyone – regardless of whether you’re A, B, O or AB.

For those with specific health conditions (diabetes, coeliac disease, kidney issues), tailored advice from a clinician or registered dietitian is essential. Blood group may come up in certain research contexts but has little impact on day-to-day diet planning.

Should You Worry About Your Blood Type?

Some readers may be concerned by references to infections like cholera or smallpox being linked to blood group O or AB. These associations are mostly historical or observed under very specific circumstances. Modern public health practice does not screen for disease risk based on ABO group alone.

Even for cardiovascular disease or thrombosis – where non-O groups carry slightly higher risk – the effect is modest compared with traditional factors such as age, obesity, high blood pressure or diabetes.

For COVID-19, current data show only minor differences in risk by ABO group; vaccination status and underlying health matter far more.

The Bottom Line

This new study out of Greece is intriguing. It adds another layer to our understanding of how biology and behaviour interact. Blood group may gently sway our dietary choices – but it doesn’t write our shopping list or dictate our health outcomes.

The most significant takeaway? Lifestyle wins out every time. Quitting smoking, exercising regularly, maintaining a balanced diet rich in plants and low in processed foods will do more for your wellbeing than matching your meals to your blood type chart.

If future research shows stronger effects of blood type on diet response or disease risk, recommendations might shift. For now though – as reinforced by experts at leading medical institutions – following general healthy eating guidelines remains your best bet.

So next time someone offers you a meal plan based solely on your blood group, remember: science says the basics work for everyone.