Researchers at Copenhagen University Hospital tested that assumption in two long-running Danish cohorts covering more than 116,000 people, tracking who died over the following years.
People with the highest HDL levels were not the healthiest. Men with HDL above about 116 mg/dL had roughly double the death risk of men in the midrange, and women above about 135 mg/dL had about 70 percent higher risk. The lowest risk sat in the middle of the range, not at the top.
The result challenged how HDL is usually read. Later pooled analyses across other countries found the same U-shaped pattern, extreme highs tracking with more illness and death rather than less. Nobody has proven why; it may be that very high HDL is a marker of underlying inflammation rather than a cause of harm.
Read the original study
Madsen et al., European Heart Journal, 2017 · doi.org/10.1093/eurheartj/ehx163
More was not better.
Source
- Madsen, C. M., Varbo, A., & Nordestgaard, B. G. (2017). Extreme high high-density lipoprotein cholesterol is paradoxically associated with high mortality in men and women: two prospective cohort studies. European Heart Journal, 38(32), 2478–2486. https://doi.org/10.1093/eurheartj/ehx163