4w ago

Is There a Correlation between Dietary and Blood Cholesterol? Evidence from Epidemiological Data and Clinical Interventions

pmc.ncbi.nlm.nih.gov

Conclusion:

We confirm from the review of the literature on epidemiological data, meta-analysis, and clinical interventions where dietary cholesterol challenges were utilized that there is not a direct correlation between cholesterol intake and blood cholesterol. This lack of correlation is mainly due to the compensatory mechanisms exerted by the organism to manage excess dietary cholesterol, including decreases in cholesterol absorption and down-regulation of cholesterol synthesis. A great number of epidemiological studies and meta-analysis indicate that dietary cholesterol is not associated with CVD risk nor with elevated plasma cholesterol concentrations. Clinical interventions in the last 20 years demonstrate that challenges with dietary cholesterol do not increase the biomarkers associated with heart disease risk. Further, in the specific circumstances where eggs are the source of dietary cholesterol, an improvement in dyslipidemias is observed due to the formation of less atherogenic lipoproteins and changes in HDL associated with a more efficient reverse cholesterol transport. However, if the cholesterol sources are consumed with saturated and trans fats, as happens in the Western diet pattern, increases in plasma cholesterol may be observed. The most recent epidemiological data and clinical interventions for the most part continue to support the USDA 2015 dietary guidelines that removed the upper limit of dietary cholesterol.

<details class="spoiler"><summary>Summary</summary>

The document reviews the relationship between dietary and blood cholesterol, highlighting that recent epidemiological studies and clinical interventions have found no direct correlation between the two. It notes that outdated dietary guidelines limited cholesterol intake to 300 mg/day, but newer research suggests that dietary cholesterol does not significantly impact blood cholesterol levels.

The review discusses how dietary cholesterol from eggs does not increase the risk of cardiovascular disease (CVD) and may even have beneficial effects on plasma lipoprotein subfractions and HDL cholesterol. It also mentions that the body has mechanisms to manage excess dietary cholesterol, such as decreased absorption and down-regulation of cholesterol synthesis.

The document concludes that current evidence supports the removal of upper limits on dietary cholesterol, as recommended by the 2015 USDA dietary guidelines.

</details>

15 comments

Epidemiology is difficult, and it's good to keep in mind that the conclusions we draw from counting things and finding correlations may be confounded by many variables.
Not in this review but it is perhaps worth mentioning that the only statistically significant finding in Women's Health Initiative randomized controlled trial was that women with a history of heart disease faced a 26% increased chance of complications such as heart attack on a low saturated fat diet:
The HR for the 3.4% of women with CVD at baseline was 1.26 (95% CI, 1.03-1.54).
Eggs aren't bad for you in terms of heart disease:
In this study, an increase of one egg per day was not associated with any CVD risk. In fact, in an updated meta-analysis that included multiple cohorts from the US, Europe, and Asia, moderate egg consumption was associated with no risk of developing CVD overall and lower risk in Asian populations
Substituting carbs with eggs for breakfast results in a lowering of blood cholesterol:
Substituting high carbohydrate breakfast with eggs resulted in a similar lowering in plasma LDL cholesterol compared to baseline in 30 subjects following a randomized crossover study in which each breakfast was followed for 4 weeks [45].
Dietary cholesterol increases the size of plasma cholesterol particles. Smaller cholesterol particles are correlated with atherogenic dyslipidemia.
Regarding lipoprotein metabolism, dietary cholesterol leads to the formation of the large LDL particles that are known to be less atherogenic [32] and reduces the concentration of small LDL
The body is able to regulate plasma cholesterol levels:
Therefore, the handling of dietary cholesterol by the body can be explained by decreased absorption and down-regulation of synthesis.
- If having breakfast, substituting carbs with eggs results in a lowering of blood cholesterol:
  This is rather surprising. I wonder if in that 4 week window people reduced their damaged LDL?
  
  I also wonder if the time matters when replacing the carbohydrates with eggs? I think our bodies respond differently to meals at different times of day. Is there only a clear benefit at breakfast-time?
The guidelines from the 1960s were not based on epidemiological data, meta-analysis or clinical intervention; they were construed as a consensus based on the current information available at that time [ 1 ].
This paper isn't pulling it's punches.
High blood pressure is considered a major risk factor for developing cardiovascular disease (CVD) [27 ]. Therefore, hypertensive patients must take further precautions to maintain a healthy diet, including, according to some researchers, reducing cholesterol intake.
And we have established a ketogenic diet will reverse hypertension after a few months.
dietary cholesterol leads to the formation of the large LDL particles that are known to be less atherogenic [32]
It's always nice to see this called out.
Mechanisms to Manage Dietary Cholesterol
I loved this section, defined the feedback mechanisms nicely.
Overall when epidemiology is noisy it means the variables being examined are not the ones we should be concerned about. i.e. we are asking the wrong questions.
This is a fun paper to read, thank you for sharing it.
- a ketogenic diet will reverse hypertension after a few months.
  This happened to me. I was glad to see it gone. No thanks needed, I like meta-analysis because it means someone more familiar with the literature than I am has done a lot of the heavy lifting!

15 comments