Genetic and biochemical studies have indicated an important role for lipid metabolism in human longevity. Ashkenazi Jewish centenarians and their offspring have large low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particles as compared with control individuals. This profile also coincided with a lower prevalence of disease. Here, we investigate whether this observation can be confirmed for familial longevity in an outbred European population and whether it can be extended to sporadic longevity in the general population.
Methods and Findings
NMR-measured lipoprotein profiles were analyzed in 165 families from the Leiden Longevity Study, consisting of 340 long-lived siblings (females >91 y, males >89 y), 511 of their offspring, and 243 partners of the offspring. Offspring had larger (21.3 versus 21.1 nm; p = 0.020) and fewer (1,470 versus 1,561 nmol/l; p = 0.011) LDL particles than their same-aged partners. This effect was even more prominent in the long-lived siblings (p < 10−3) and could be pinpointed to a reduction specifically in the concentration of small LDL particles. No differences were observed for HDL particle phenotypes. The mean LDL particle sizes in 259 90-y-old singletons from a population-based study were similar to those in the long-lived siblings and thus significantly larger than in partners of the offspring, suggesting that the relevance of this phenotype extends beyond familial longevity. A low concentration of small LDL particles was associated with better overall health among both long-lived siblings (p = 0.003) and 90-y-old singletons (p = 0.007).
Our study indicates that LDL particle profiles mark both familial and sporadic human longevity already in middle age.
Offspring of families from the Leiden Longevity Study had larger and fewer LDL particles than same-aged partners, suggesting that even in middle age LDL particle profiles are associated with longevity.
It is not clear why some people go on to live longer than others do. Some studies have shown that close relatives of long-lived people are themselves more likely to live for a long time; these findings suggest that there is probably a genetic basis for long life. However, the actual mechanisms involved have not yet been worked out. Some genes coding for proteins involved in fat metabolism, such as APOE, APOB, and CETP, have been associated with long life, suggesting a link between the way fat gets metabolized and the aging process. One study that supports this idea found that the children of 100-year-old people had larger lipoprotein particles (assemblies of proteins and fats that carry cholesterol and triglycerides in the blood) than similarly aged control individuals. However, studies such as this are very prone to “false positive” findings and therefore need to be backed up by confirmatory evidence. In addition, the previous study was performed in a very specific population (Ashkenazi Jewish people), and it is important to find out whether the findings are also true in other populations.
Why Was This Study Done?
The research group carrying out this study wanted to address several distinct questions to do with the genetics of aging. Firstly, they wanted to see if they could confirm previous findings associating large lipoprotein particles with longer life, but looking at people who were more representative of the general European population and not from a genetically isolated population. Secondly, they wanted to see whether this association applied to only long-lived people whose family members were also long-lived, or to long-lived people in general. Finally, they wanted to find out if the large lipoprotein particles were associated with better health.
What Did the Researchers Do and Find?
In the study, the researchers looked at long-lived people from across The Netherlands whose relatives were also long-lived. For this, they recruited 340 men aged over 89 and women aged over 91 into the study, all of whom had at least one similarly long-lived sister or brother. Their children (511 individuals), and the partners of their children (243 people), were also recruited into the study, with the partners acting as “controls.” The researchers also studied 259 people who had just turned 90 years old; these people were included to see whether particular characteristics of lipoproteins existed in long-lived people whose longevity did not run in families. All the participants gave blood samples, and the researchers then measured the size and amount of different lipoprotein particles in these samples. Two types of lipoprotein particles were looked at: low-density lipoprotein (LDL, often termed “bad cholesterol”) and high-density lipoprotein (HDL, sometimes called “good cholesterol”). The researchers found that the children from the long-lived people had larger and fewer LDL particles than their partners (the “control” individuals) just like their long-lived parents. Thus even though the children were not long-lived themselves, LDL particles marked the fact that they have a higher chance of becoming long-lived in the future. Similar changes in LDL particles were found for long-lived people whose relatives were not also long-lived. Interestingly, simply the level of cholesterol—the classical risk factor for cardiovascular disease—did not appear to play a role. Thus it seems that it is not the amount of cholesterol that is important in longevity but how it is packaged. Better health status was also associated with a lower proportion of small LDL particles in the blood, supporting these findings. No characteristics of the HDL particles seemed to be associated with longevity.
What Do These Findings Mean?
These findings confirm those from a previous study in Ashkenazi Jewish people that suggested that the size of LDL particles in the blood was associated with long life. The nature of this association is not clear; some studies indicated that small LDL particles increase the risk of cardiovascular disease but small LDL particles may also be harmless themselves and reflect the efficiency of other processes causally related to aging.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0030495.
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