Does Dietary Cholesterol Really Increase Your Cardiovascular Disease Risk?
Title: Dietary cholesterol and cardiovascular disease: a systematic review and meta-analysis
Author: Berger et al
Journal: American Journal of Clinical Nutrition
Objective: The authors examine the effects of dietary cholesterol on CVD risk in healthy adults by using systematic review and meta-analysis.
According to the American Heart Association, and most major medical groups, dietary cholesterol increases your risk of
- Coronary Heart Disease (CHD)
- Heart attack (myocardial infarction)
- Stroke (CVA or Cerebrovascular accident)
Because of these risks, dietary guidelines suggest we limit our daily intake of cholesterol to 300 mg per day. This recommendation is based on the 50 year old presumption that a reduction in dietary cholesterol intake would lead to a reduction in blood LDL cholesterol.
During the last half a century, evidence linking dietary cholesterol to cardiovascular disease risk has been mixed. Some studies have found increased risk with increased intake, while others have found no increased risk at all.
Because of these inconsistencies, the authors of this study sought to do a systematic review and meta-analysis of published studies to “determine the potential effect of dietary cholesterol on incident CVD and on serum concentrations of total cholesterol, LDL cholesterol, HDL cholesterol, LDL to HDL ratio, and triglycerides in adults.”
A systematic review and meta-analysis, while technically different, are functionally similar. The goal is to combine and summarize the results different studies on a given subject in the hope of identifying patterns among study results. It is the gold standard among scientists and medical professionals for interpreting research results.
The authors of this study used prospective studies that quantified dietary cholesterol from various research databases ( MEDLINE, Cochrane Central, and Commonwealth Agricultural Bureau Abstracts).
They then use complex statistical methods to combine the data from all the different studies and draw conclusions.
Ultimately, 40 studies containing more than 361,000 subjects were included in the review (from 1979-2013).
Dietary cholesterol was not statistically significantly associated with
- Coronary artery disease (no summary RR),
- Ischemic stroke (which is the most common type of stroke) (summary RR:1.13; 95% CI: 0.99, 1.28) or
- Hemorrhagic stroke (summary RR: 1.09; 95% CI: 0.79, 1.50).
Dietary cholesterol did statistically significantly increase both
- Serum total cholesterol (17 trials; net change: 11.2 mg/dL; 95% CI: 6.4, 15.9) and
- Serum low-density lipoprotein (LDL) cholesterol (14 trials; net change: 6.7 mg/dL; 95% CI: 1.7, 11.7 mg/dL).
Increases in LDL cholesterol were not statistically significant when daily cholesterol intake exceed 900 mg/d.
Dietary cholesterol also statistically significantly increased
- Serum high-density lipoprotein (HDL) cholesterol (the good cholesterol) (13 trials; net change: 3.2 mg/dL; 95% CI: 0.9, 9.7 mg/dL) and the
- LDL to highdensity lipoprotein ratio (5 trials; net change: 0.2; 95% CI: 0.0, 0.3).
Dietary cholesterol did not statistically significantly change serum triglycerides or very-low-density lipoprotein concentrations.
The reviewed studies were not similar enough from study-to-study and had enough methodological flaws to reserve drawing any major conclusions regarding the effects of dietary cholesterol on cardiovascular disease risk.
The authors go on to suggest more carefully designed and conducted studies should be done to better evaluate the relationship between dietary cholesterol and cardiovascular disease risk.
My opinion is that you should continue to follow the the American Heart Association recommendations on the subject and limit your dietary cholesterol intake until we have better data on the subject.
Berger, S., Raman, G., & Vishwanathan, R. (2015). Dietary cholesterol and cardiovascular disease: a systematic review and meta-analysis. American Journal of Clinical Nutrition, 102(2), 276-294. doi:10.3945/ajcn.114.100305