In general, we may be taking a very one-sided look at blood cholesterol levels. The side appears to be that cholesterol is an evil invader in the human bloodstream. Several points suggest that there are two sides to the whole story.
The first point is that cholesterol is not a harmful substance that can sneak into us through eating too much of it. It is well established that about 80-85% of the cholesterol in the body is made in the liver. A dramatic cut of 50% in dietary cholesterol can have no more than a questionably significant 5-7% impact of lowering circulating cholesterol. This brings up a good question, “if cholesterol is bad, why would the liver make it in the first place?”
The answer is, of course, that cholesterol is not evil. Rather it is an essential component of the human body. Cholesterol is used for the following functions:
A new study reported in the October, 2011 issue of Journal of the American Geriatrics Society looked at the relationship between specifically LDL or “bad” cholesterol levels and total mortality in seniors. First a few comments about “bad” cholesterol are in order. LDL cholesterol takes the newly made cholesterol from the liver and delivers it to where it will be used. It is only “bad” when other things happen to it to get it off track and doing other things. If we do not make LDL cholesterol, we do not make essential hormones or repair cell membranes.
Back to the new study. The researchers stated objective was “to clarify the association between cholesterol and non-cardiovascular mortality and to evaluate how this association varies across age groups.” The relationship between bad cholesterol and non-cardiovascular mortality or death was inverse. This means that those with lower LDL cholesterol had higher rates of mortality, or the higher the LDL cholesterol, the lower the mortality.
For each increase of 39 mg/dL in LDL cholesterol, there was a 12% decrease in the risk of non-cardiovascular mortality. The relationship became more pronounced with each 10-year age group from 55-64 on up to 85 and older.
The study was not designed to look at why this inverse relationship occurred but simply did it occur. The researchers commented, “Further research is required to examine the mechanisms underlying this association.”
The mechanisms likely related to the declining levels of important signaling steroid hormones with age. As the body struggles to try to make steroid hormones it likely requires greater amounts of cholesterol to get the job done. Declining steroid hormone levels with aging have been linked to higher mortality in other research. A 2010 study looked at steroid hormone levels in men 20 years and above and found that men with low testosterone had 40-50% increased mortality risk over the next 9 years.
The heavy specialization in modern health care has tended to cause somewhat isolated perspectives on different risk factors. The cardiovascular arena looks at LDL cholesterol only from the cardiovascular perspective. Progressive lowering of it in adults without known heart disease has even been brought into question as the data does not support any benefit from this. Any proven benefit of progressive lowering LDL cholesterol has only been established in persons who have already had heart attacks.
As mentioned above LDL cholesterol is only a problem when it gets off track from its intended use in the body (hormones, cell repair) and it does other things. Understanding how it gets off track and gets involved in processes other than its natural intended use really is the key to knowing if one’s cholesterol will cause trouble or actually help.
Perhaps cholesterol is actually an ally in the battle of healthy aging as long as it behaves at work! Part II of this blog will be about those issues.
Newson et al. Association Between Serum Cholesterol and Noncardiovascular Mortality in Older Age. Journal of the American Geriatrics Society, 2011;59:1779–1785. Menke et al. Sex steroid hormone concentrations and risk of death in US men. American Journal of Epidemiology, 2010;171:583-592.