Strawberry margarita – the perfect longevity drink. (Photo by bookgrl)
According to conventional wisdom, LDL is the "bad cholesterol" and HDL is the "good cholesterol". While there is plenty of evidence showing this is an oversimplification, it is generally agreed that the higher your HDL is, the better. In fact, I've never seen anyone suggest a "maximum" HDL level for a healthy person.
One of the many strange things you hear most doctors recommend is that you reduce your total cholesterol once it's above a certain level, despite what your LDL and HDL are. That is, even if HDL makes up most of your total cholesterol, you may still get a warning that your total cholesterol is "too high". But why would you want to reduce your HDL cholesterol?
High HDL is generally believed to be associated with longevity, at least to a degree. For example, centenarians and supercentenarians tend to have higher HDL than the general population. To my knowledge, large population studies on HDL and longevity are relatively rare, however – which is why I found this new paper from the American Journal of Cardiology pretty interesting (link).
The study (which began in 1979) looked at the probability of 652 men, aged 65 years, to reach 85 years of age. The authors hypothesized that men with higher HDL cholesterol levels in middle age would be less likely to die before 85 years of age than men with lower HDL levels.
For the analysis, participants were categorized into three groups based on their HDL cholesterol: <40, 40–50 and >50 mg/dL. Converted to mmol/L, the ranges are <1, 1–1.3 and >1.3 mmol/L. To me, these categories seem like they're in the lower range of the healthy spectrum, but then again, average HDL levels in men in the US are said to be 40-50 mg/dL. According to the American Medical Association, less than 40 mg/dL is undesirable and higher than 60 mg/dL is desirable.
The age-adjusted hazard ratios for death before 85 years of age in the three groups were as follows: 1.00 for those with HDL < 40 mg/dL, 0.99 for those with HDL between 40–50 mg/dL, and 0.77 in those with HDL > 50 mg/dL. In the fully adjusted model (which accounted for age, LDL, hypertension, smoking, BMI, etc), the hazard ratios were 1.00, 1.01 and 0.72, respectively. That is, men with HDL higher than 50 mg/dL had a ~28% lower risk of dying than those with HDL lower than 50 mg/dL.
Immediately we can see that it doesn't make much difference whether the participants' HDL was below 40 or between 40 and 50 mg/dL – the risk of dying before 85 years of age was pretty much the same for both groups. Only once their HDL cholesterol levels were above 50 mg/dL was there a significantly lower risk.
Furthermore, when the authors analyzed the data further, they found that each 10-mg/dL increment in HDL cholesterol was associated with a 14% decrease in risk of dying before 85 years of age. In other words, the higher their HDL, the higher the survival rate.
This is all very good news. Reaching a HDL level of, say, 80 mg/dL (~2.1 mmol/L) is not at all impossible as long as you plan your diet properly, and would give you a significantly lower risk of dying from cardiovascular disease – which is the number one killer in the 65–85 age group.
The baseline characteristics of the participants reveal some interesting things too. First, the LDL cholesterol was pretty much the same in all groups: around 160–168 mg/dL. Body mass index, on the other hand, was inversely correlated with HDL levels: those with the lowest HDL levels had a mean BMI of 27.5, while those with the highest HDL levels had a mean BMI of 25.8.
While alcohol is known to increase triglycerides in the short term, it also increases HDL. Indeed, alcohol consumption was positively correlated with HDL levels. The percentage of participants who drank at least 2 alcoholic beverages per day was ~14% in those with the lowest HDL, ~18% in those with average HDL and ~38% in those with the highest HDL. This might explain, in part, why moderate alcohol consumption is associated with increased longevity.
So, if your total cholesterol is high and it's mostly due to high LDL, that may be a potential cause for worry – although it's good to keep in mind that there are several types of LDL, some more harmful than others. However, if you have high cholesterol due to high HDL, well then you should be happy!
For more information on HDL cholesterol and how to increase it, see these posts:
Hibiscus Tea Increases HDL, Lowers LDL and Triglycerides
Refined vs Red Palm Oil and Cholesterol
What a "Heart-Healthy" Diet Does to Your Cholesterol Levels
Anthocyanins from Berries Increase HDL and Lower LDL