Blood of long-livers is significantly different, — study

Swedish scientists from the Karolinska Institutet have discovered differences in the blood of long-lived people.

While long-livers used to be considered something rare and unusual, since the 70s of the last century, their number has roughly doubled every 10 years. Attempts by scientists to understand the secrets of longevity include the study of complex interaction genetic predisposition and lifestyle factors.

A recent study by researchers from the Karolinska Institutet found some common biomarkers, including cholesterol and glucose levels in people over 90 years of age. So far, studies of long-livers have often been small in scale and focused on a select group, for example, with the exception of long-livers living in nursing homes.

The study, conducted by Swedish researchers, was the largest of its kind. They compared the biomarker profiles measured throughout life in long-lived people and those who lived less.

The study included data on 44 thousand elderly Swedish citizens, who underwent a health assessment at the age of 64-99 and made up the sample of the so-called “Amoris cohort”. The participants were followed for 35 years. Of these, 1,224 people, or 2.7%, lived to be 100 years old. The vast majority (85%) of long-livers were women.

The study included 12 blood biomarkers, related to inflammation, metabolism, liver and kidney function, and potential malnutrition and anemia. All of them were related to aging or mortality in previous studies. 

The biomarker associated with inflammation was uric acid, a waste product formed during the digestion of certain foods. The researchers also looked at markers related to metabolism, which included total cholesterol and glucose levels, as well as markers related to liver function, such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin, gamma-glutamyltransferase (GGT), alkaline phosphatase (ALP) and lactate dehydrogenase (LD).

In addition, the researchers analyzed the level of creatinine, associated with kidney function, as well as iron levels and total iron binding capacity (TIC), associated with anemia. It was studied albumin level — nutrition-related biomarker. 

Scientists have found, that those who lived to be 100 years old, usually had lower glucose levels, creatinine and uric acid after the age of sixty. Although the median values of most biomarkers in long-livers and people under 100 years of age did not differ significantly, long-livers rarely showed extremely high or low values. 

For example, a very small number of long-lived people have a level of glucose at the beginning of life was higher than 6.5 mmol/L or creatinine level was higher than 125 μmol/L. For many biomarkers, both in long-livers and people under 100 years of age, the values were outside the range considered normal by clinical guidelines.

The researchers found, that all 12 biomarkers, excluding only alanine and albumin, are associated with the likelihood of living to 100 years of age. People in the five groups with the lowest levels of total cholesterol and iron were less likely to live to be 100 years old than those with higher levels. Study participants with higher glucose and creatinine levels, uric acid and markers of liver function also had lower chances of living to 100 years of age. 

In absolute terms the differences in some biomarkers were quite small, while the difference in other biomarkers was more significant. For example, for uric acid, the absolute difference was 2.5 percentage points. This means, that people with of the group with the lowest uric acid levels, were 4% likely to live to 100 years of age, while only 1.5% of those in the group with the highest uric acid levels lived to 100 years of age.

The results of the study were published in the journal GeroScience

Source: The Conversation; ScienceAlert