A cross-sectional study, the research came to the conclusion by measuring whole blood NAD+ level in the test subjects.
It is said to offer a distinctive difference from existing NAD+ related studies as it looks into the Chinese population specifically.
The findings meant that it would be crucial to consider gender difference in future NAD+ related studies in the future, said the researchers from BYHEALTH and several China institutions such as Shanghai Jiao Tong University School of Medicine and Jinan University.
Findings of the study were published in Frontiers in Endocrinology.
Data from 1,518 participants were analysed for this research.
These participants have a mean age of 43 years old and were recruited from the Jidong community located in Tangshan city, northern China from 2019 to 2020.
Over half of them (52.6 per cent) were men.
The participants were also categorised into five groups based on their age: 1) 29 and below, 2) between 30 and 39, 3) between 40 and 49, 4) between 50 and 59, and 5) 60 and above.
This is to find out if there is any link between NAD+ levels and ageing.
Blood samples were collected from the participants’ large antecubital veins – veins from the upper limb – after an overnight fasting.
The researchers then performed a general liner regression model to find out the association between NAD+ contents and ageing. They also conducted an analysis based on gender.
Gender difference
The whole blood NAD+ level in men was significantly higher than that of women.
In men, the NAD+ level was 34.5 ± 5.4μmol/L, while that of women was 31.3 ± 5.2 μmol/L, which is a significant difference with a p-value of less than 0.001.
Overall, the average levels of whole blood NAD+ of all the subjects was 33.0 ± 5.5 μmol/L.
“The blood NAD+ contents show different trends with aging in men and women. The blood NAD+ decreased gradually with aging in men, while the female blood NAD+ showed a trend of fluctuations,” the researchers said.
The researchers speculated that the NAD+ fluctuation in women might have been influenced by sex hormones.
Female menopause generally occurs at around 50 years old, and the sex hormones are greatly altered during this time.
They stressed that further investigation needs to be conducted on the relationship of NAD+ contents and sex hormones to find out more.
Limitations
As only NAD+ levels were measured, the researchers acknowledged that this could be a limitation of the study, as they could have also measured the levels of NAD+ precursors.
“Data on the NAD+ precursors, such as free NA, NAM, NADH would give more information in the NAD+ related studies but were absent in the current study.”
They also pointed out that future studies could measure NAD+ levels in specific organs and tissues.
“We only tested the NAD+ level in whole blood samples so that it could reflect the association of aging and NAD+ contents in human whole blood.
“Moreover, the whole blood NAD+ is likely to reflect NAD+ levels in red blood cells. Further studies should be conducted to explore the association in other tissues or organs.”
Source: Frontiers in Endocrinology
Association of Human Whole Blood NAD+ Contents With Aging
https://doi.org/10.3389/fendo.2022.829658
Authors: Fan Yang et al