International Business Department           Liu Bojia           October 19, 2023

  Humans, including scientists, have never stopped exploring the secrets of longevity. In the past, if 100 years of age was set as the limit of longevity, the sample size would be too rare, thus making it difficult to study the secret of longevity among these individuals. However, according to relevant statistics, the number of centenarians has been on the rise since the 1950s, almost doubling every 10 years.

  The rapidly increasing number of centenarians has also provided scientists with a wider range of research into what exactly makes these individuals different from others in terms of longevity?

  A Japanese cohort study has found that some indicators of inflammation in the blood may be able to be used to predict longevity, in particular low levels of inflammation associated with interleukin-6, tumour necrosis factor-alpha and longevity. However, due to small sample sizes, more information remains a mystery.

  Recently, a team of researchers from the Karolinska Institutet in Sweden conducted a study involving a much wider population analysis, with data from health assessments of more than 44,000 Swedish volunteers, who had blood samples collected between the ages of 64-99 years old, and who were followed up for a long period of time. More than 1,200 volunteers reached the age of 100 during the approximately 35-year follow-up period, representing 2.7 per cent of the surveyed population, and the vast majority were female.

  A total of 12 blood biomarkers were included in the analysis, including uric acid, which is used to indicate levels of inflammation, cholesterol and glucose, which are metabolism-related, and liver enzymes and creatinine, which are indicative of liver and kidney function.

  To better confirm the link, the researchers compared the biomarker levels of centenarians with those of individuals with shorter lifespans when they were equally young, and they also compared the biomarker differences between centenarians.

  The data analysed for the study showed that of the 12 markers, 10 were associated with reaching 100 years of life expectancy, with the exception of alanine aminotransferase and albumin. The paper notes that although albumin has been found to be associated with individual survival in the past, this effect may only be seen at younger ages and become less pronounced in older people who are too old.

  Overall, lower glucose levels, creatinine and uric acid in the blood in the 60s were positively correlated with becoming a centenarian in the future. People in the group with the lowest uric acid levels were 2.5 per cent more likely to be centenarians compared to the group with the highest uric acid levels. And the fact that uric acid usually reflects the level of inflammation in the body suggests that inflammation remains one of the most important determinants of longevity.

  At the same time, centenarians have relatively stable ranges of these indicators, and do not have particularly high or low indicators like other individuals.

  There are also some unexpected associations among the various indicators, such as the fact that individuals with high total cholesterol levels are more likely to be centenarians, and many health guidelines now recommend lowering cholesterol levels. In addition to this, centenarians will have levels of alkaline phosphatase and lactate dehydrogenase look beyond the clinically recognised standard range.

  In addition to the markers mentioned above, there are also iron, total iron binding capacity, glutamyl transferase, and aspartate aminotransferase that are associated with living to 100.

  The paper points out that these medical guidelines are usually set based on a much younger, healthier population, whereas in older people, many biochemical processes have changed during the aging process, and the standard ranges for the various biomarkers change accordingly. For example, there are other studies that have also found that higher cholesterol levels in older adults are associated with lower mortality rates.

  Although the study did not indicate which lifestyle habits, or which foods to consume, were associated with longevity, the authors suggest that keeping an eye on metabolic, liver and kidney-related indicators as we age is not a bad idea.