Evidence for blood group differences to be meaningfully involved in natural variations in longevity is nebulous at best. Nonetheless, papers emerge every so often on this topic to theorize and collect more evidence, but continue to reinforce the lack of compelling data:
ABO antigens have been known for a long time and yet their biological meaning is still largely obscure. Based on the available knowledge of the genes involved in their biosynthesis and their tissue distribution, their polymorphism has been suggested to provide intraspecies diversity allowing to cope with diverse and rapidly evolving pathogens. Accordingly, the different prevalence of ABO group genotypes among the populations has been demonstrated to be driven by malaria selection. In the similar manner, a particular ABO blood group may contribute to favour life-extension via biological mechanisms important for surviving or eluding serious disease.
There are only five reports suggesting a possible association between ABO blood groups and ageing/longevity features, among those only two performed on centenarians and only one performed by molecular methods. In the first one, a significant increase of A blood type was observed in the healthy elderly male population over 64 years of age from UK, but it is not possible to consider this study for the very low age taken into account. In a study carried out on a small sample of very longevous Turkish population, no association was found; however, the validity of age claims was very questionable because birth certificates were not available, so also this study cannot be considered.
A more recent study investigated the association between blood groups and life expectancy in the Japanese population. The authors compared frequencies of ABO blood groups in 269 centenarians living in Tokyo and those in 7153 regionally matched controls. Group B was observed more frequently in centenarians than in controls, suggesting that group B might be associated with exceptional longevity. The authors suggested that group B individuals are more likely to survive age-related diseases rather than escape them, since 33% of the centenarians were free of age-related diseases, but this did not correlate with the group B.
In a further study, to validate these results, [researchers] collected data on the ABO blood groups of patients who died in a United States tertiary care hospital over a 1-year period. If group B was a marker for a longer lifespan, it would be expected that the percentage of group B patients would rise with age at the time of death and those of other blood groups would decline. A total of 772 patients were included in the study and data were presented as ABO proportion stratified by age. The authors found that the percentage of group B patients declined with age, and this result was statistically significant. None of the other blood groups showed a statistically significant increase or decrease when plotted against decade of death. Overall, these results suggest that group B is not a marker for longevity, at least in US.
We have recently investigated the relationship between ABO group and longevity in a small sample of homogeneous Sicilian centenarians (n = 38) and young controls (n = 59). Our group of centenarians (age range 100-107) had no cardiac risk factors or other age-related diseases. The control group (age range 45-65) was recruited from blood donors and judged to be healthy on the basis of clinical history and blood tests. Samples were genotyped by molecular biology to determine ABO blood group and Chi Square analysis was used to determine the statistical significance of differences in ABO of centenarians and controls. Our pilot study shows a not-significant increase of A1 allele in Sicilian centenarians.
In the generation of centenarians under study, the control of cardiovascular disease, in fact plays a key role in the longevity attainment. So, the Sicilian results, that need to be confirmed in a larger sample of centenarians, also taking into account the gender due to its relevance in immune-inflammatory responses, are in line with the previous statements. So, people carrying A1 allele should be advantaged in attaining longevity because of the lower levels of the serum soluble inflammatory marker E-selectin linked to this blood group, so avoiding or delaying cardiovascular events.