Your Blood Type Is Not an Aging Test
The blood type on your chart was recorded for transfusion safety. It has since been used in diet books and a steady stream of wellness content suggesting your ABO group predicts how well you will age. A review published in July in Mechanisms of Ageing and Development went back through the evidence, and the authors' conclusion is far more modest than any of that.
What the researchers found
Balistreri and colleagues at the University of Palermo ran a structured search of the major biomedical databases, focused mostly on studies from the last five years, and asked one question: can ABO blood group serve as a reliable biomarker of aging? [1]
Their answer is no. They report that ABO phenotypes are associated with several age-related conditions, including cardiovascular disease, thrombotic disorders, diabetes, cancer, allergies, and cognitive disorders. Nevertheless, they describe the underlying data as contradictory and dependent on ethnicity, genetic background, and environmental factors. On longevity specifically, they state that findings remain inconsistent and appear to vary from one population to another.
The one pattern they do call consistent is narrower than the popular claims. Non-O blood groups (A, B, and AB) carry a higher risk of thrombotic and cardiovascular events, which the authors attribute to differences in coagulation factors, endothelial function, and hemostatic balance.
Their conclusion, in plain terms: ABO blood group is unlikely to be an independent biomarker of aging, and is better understood as a modest, context-dependent modifier of the biological pathways that contribute to age-related disease.
The type of review is important, because it determines how much confidence the conclusion deserves. This is a narrative review, which means the authors selected and synthesized the literature without the formal protocol and pooled statistics that a systematic review or meta-analysis requires. That is a reasonable way to survey a contradictory field, and it is a weaker evidence class than a meta-analysis. The conclusions are these authors' interpretation of the literature rather than a calculated result.
What the primary studies on blood type and clotting show
The primary studies behind the clotting association have found it consistently.
There is a prospective cohort of 1,708 patients with cancer in which non-O blood type predicted venous blood clots, though only after the first three months of follow-up (subdistribution hazard ratio 1.79, 95% CI 1.12 to 2.85) [2]. That association weakened once the researchers adjusted for factor VIII, a coagulation protein that people with non-O blood carry at higher levels. This is the proposed mechanism, and that adjustment supports it.
One of the most widely reported ABO findings in recent years is consistent with this. A genome-wide association study of patients hospitalized with severe COVID-19 in Italy and Spain found higher risk in blood group A (odds ratio 1.45) and a protective effect in blood group O (odds ratio 0.65) [3].
These associations are consistent across studies. How large they are is the other question. Pooled individual-level data from 112 cohort studies across 34 countries, covering more than 1.5 million people, attributed roughly 57 percent of ten-year cardiovascular disease in women and roughly 53 percent in men to five modifiable risk factors: body mass index, systolic blood pressure, non-HDL cholesterol, current smoking, and diabetes [4].
Comparing the two gives a sense of scale. Blood type may change cardiovascular risk by a modest amount. Blood pressure, smoking, and metabolic health account for more than half of it.
What knowing your blood type is useful for
Patients ask me about the blood type diet more often than you might expect, and this review is a good occasion to answer it properly.
Blood type is fixed. A risk factor you cannot change is only useful if knowing it changes what you or your clinician actually do, and for most people this one does not. Knowing it certainly does not help you decide what to eat. When researchers took 68 participants in a 16-week trial of a low-fat vegan diet and compared their results by blood type, they found no difference in body weight, body fat, blood lipids, or blood sugar control between type A, type O, and everyone else [5].
A fixed marker is useful as context. If a person with non-O blood is facing surgery, a long stretch of immobility, or an estrogen-containing medication, that is reasonable for their clinician to hold in mind alongside the rest of the history. It is one input among many.
The habit of mind I would rather people take from this review is proportion. An exotic, fixed risk factor is more interesting to read about than blood pressure. The unglamorous factors are the ones with both the strongest evidence behind them and the most room to change.
Where blood type belongs in your health history
Your blood type is fixed, so the useful place to spend your attention is on the risk factors that are not.
If you have non-O blood and a personal or family history of blood clots, mention it to your provider, particularly ahead of surgery, extended travel, or starting a hormonal medication. It belongs in the history rather than at the top of it.
Blood-type diets remain unsupported. If a way of eating works well for you, your ABO group is not the reason.
The five factors in that global analysis are the ones with the largest measured effect. Blood pressure, lipids, blood sugar, smoking status, and body composition can all be measured and changed, and they are all more consequential than the letter on your chart.
References
Primary research located and verified via PubMed.
Balistreri CR, Di Salvo A, Motisi C, Carella M, Gervasi F, Camilli C, Aronica TS. ABO blood groups and ageing-related outcomes: Insights from a narrative review. Mech Ageing Dev. 2026;233:112229. PMID 42448055. https://doi.org/10.1016/j.mad.2026.112229 (digest source article; publisher page blocks automated readers, so the PubMed record was used as the source of record)
Englisch C, Moik F, Nopp S, Raderer M, et al. ABO blood group type and risk of venous thromboembolism in patients with cancer. Blood Adv. 2022;6(24). PMID 35416922. https://doi.org/10.1182/bloodadvances.2021006283
Ellinghaus D, Degenhardt F, Bujanda L, et al. Genomewide Association Study of Severe Covid-19 with Respiratory Failure. N Engl J Med. 2020;383(16):1522-1534. PMID 32558485. https://doi.org/10.1056/NEJMoa2020283
Magnussen C, Ojeda FM, Leong DP, et al. Global Effect of Modifiable Risk Factors on Cardiovascular Disease and Mortality. N Engl J Med. 2023;389(14):1273-1285. PMID 37632466. https://doi.org/10.1056/NEJMoa2206916
Barnard ND, Rembert E, Freeman A, Bradshaw M, Holubkov R, Kahleova H. Blood Type Is Not Associated with Changes in Cardiometabolic Outcomes in Response to a Plant-Based Dietary Intervention. J Acad Nutr Diet. 2021;121(6):1080-1086. PMID 33288495. https://doi.org/10.1016/j.jand.2020.08.079
A note before you go
This article is educational and is not medical advice. It cannot see your history, your labs, or your family background, and your blood type is a small part of a much larger picture. If you have a personal or family history of blood clots, or you are weighing a decision about surgery, travel, or a hormonal medication, please work through it with the provider who knows your case. Your blood type is one line in that conversation, not the whole of it.
If this resonates with what you're experiencing and you'd like to explore a naturopathic approach, book a consultation with our clinic.
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