Ketogenic Diet and Cardiovascular Risk: A Meta-Analysis of 27 Randomized Trials
Summary ID06-ND-RS-00075
Research Summary
Original Publication
Ketogenic Diet and Cardiovascular Risk: A Meta-Analysis of 27 Randomized Trials
Journal
The American Journal of Clinical Nutrition, .
- Category
- 06Nutrition & Diet
- Evidence
- Meta-Analysis of Randomized Controlled Trials
- Summary Type
- Advanced
What Was Studied?
Ketogenic diets are widely used for weight management and metabolic health. They severely restrict carbohydrates, encouraging the body to use more fat for energy and produce ketones.
However, their effects on cardiovascular health remain debated.
Researchers conducted a meta-analysis of 27 randomized controlled trials involving 1,278 participants to examine how ketogenic diets affected cardiovascular risk factors compared with other dietary approaches.
The analysis evaluated several important measures:
* Total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides * Blood glucose and insulin * Blood pressure * Body weight and body mass index
The aim was to determine whether ketogenic diets produced consistently favorable changes in these measures or a combination of potential benefits and risks.
Key Findings
LDL and Total Cholesterol Increased
Ketogenic diets increased LDL cholesterol by an average of 0.35 mmol/L, equivalent to approximately 13.5 mg/dL, compared with control diets.
Total cholesterol also increased by approximately 0.36 mmol/L.
These findings are clinically important because LDL cholesterol contributes directly to the development of atherosclerosis.
Over time, elevated LDL cholesterol increases the risk of cardiovascular disease.
However, responses varied considerably between studies. The average increase does not mean that every individual following a ketogenic diet will experience the same change.
Triglycerides Decreased and HDL Cholesterol Increased
Ketogenic diets reduced triglycerides by approximately 0.20 mmol/L, equivalent to around 18 mg/dL.
At the same time, HDL cholesterol increased by approximately 0.16 mmol/L.
These changes may indicate a more favorable metabolic profile, particularly in people with elevated triglycerides.
However, an increase in HDL cholesterol does not automatically translate into protection against cardiovascular disease.
Similarly, lower triglycerides do not eliminate the potential cardiovascular implications of higher LDL cholesterol.
Blood Glucose and Insulin Levels Decreased
Compared with control diets, ketogenic diets were associated with reductions in:
* Blood glucose: 0.18 mmol/L * Blood insulin: 8.32 pmol/L
These findings suggest that severe carbohydrate restriction can improve certain measures of glucose regulation.
However, lower insulin levels alone do not establish improved insulin sensitivity.
The analysis also did not determine whether ketogenic diets prevent type 2 diabetes or provide sustained metabolic benefits over many years.
Body Weight and Blood Pressure Improved
Participants following ketogenic diets lost an average of 2.59 kg more than those following control diets.
Body mass index decreased by approximately 1.59 kg/m².
Diastolic blood pressure was also lower by approximately 1.41 mmHg.
These changes may be relevant to cardiometabolic health, particularly for people with excess body weight.
However, the average reduction in diastolic blood pressure was modest.
The meta-analysis did not establish a statistically significant overall reduction in systolic blood pressure.
Cardiovascular Benefits and Risks Did Not Move in the Same Direction
The most important finding was the combination of favorable and unfavorable changes.
Ketogenic diets reduced body weight, triglycerides, blood glucose and insulin, while increasing LDL and total cholesterol.
The results also showed substantial variation between trials.
This means that the overall cardiovascular implications cannot be determined from improvements in body weight or glucose levels alone.
Importantly, the meta-analysis evaluated cardiovascular risk factors rather than actual cardiovascular events.
It therefore did not establish whether ketogenic diets increase or decrease the risk of heart attacks, strokes or cardiovascular death.
Why It Matters for Longevity
Cardiovascular disease remains one of the major threats to healthy aging.
Atherosclerosis can develop gradually over decades, often without symptoms.
Preventing cardiovascular disease therefore requires attention to several interconnected factors, including cholesterol, blood pressure, glucose metabolism, body composition and long-term dietary habits.
The findings from Wang and colleagues offer three important insights.
1. Weight loss does not guarantee cardiovascular protection.
Reducing excess body weight may improve metabolic health, but it does not ensure that all cardiovascular risk factors improve.
2. LDL cholesterol remains important, even when other markers improve.
Lower triglycerides and blood glucose are favorable changes. However, they do not automatically offset the potential consequences of increased LDL cholesterol.
3. Long-term dietary choices should support overall cardiovascular health.
For healthy aging, the goal is not simply to achieve ketosis or short-term weight loss. It is to maintain a dietary pattern that supports metabolic health while minimizing cardiovascular risk.
This study did not directly assess biological aging, healthspan or lifespan.
Its relevance to longevity lies in demonstrating why dietary strategies should be evaluated through their broader cardiovascular and metabolic effects rather than through weight loss alone.
Clinical Perspective
This meta-analysis highlights an important limitation of evaluating dietary interventions through weight loss alone.
A diet may produce favorable metabolic changes while simultaneously increasing an established cardiovascular risk factor.
The rise in LDL cholesterol is particularly relevant.
LDL cholesterol plays a causal role in atherosclerosis. Sustained exposure to elevated LDL cholesterol contributes to plaque development and increases cardiovascular risk over time.
Therefore, reductions in body weight, triglycerides or blood glucose should not automatically be interpreted as evidence of overall cardiovascular protection.
At the same time, the findings do not establish that ketogenic diets cause cardiovascular events.
The trials assessed changes in risk factors, not long-term rates of heart attack, stroke or cardiovascular mortality.
Another important consideration is dietary composition.
Ketogenic diets can differ substantially in the types of fats and proteins consumed.
A dietary pattern emphasizing olive oil, nuts, seeds and fish is nutritionally different from one dominated by butter, cream and fatty processed meats.
However, this meta-analysis did not establish which specific dietary components explained the observed increase in LDL cholesterol.
The substantial variation between trials also limits the ability to predict an individual’s response.
For people choosing a ketogenic diet, cardiovascular assessment should therefore extend beyond body weight and glucose measurements to include the lipid profile, particularly LDL cholesterol.
Key Takeaway
Although ketogenic diets may improve triglycerides, blood pressure, body weight and blood glucose, their tendency to increase total and LDL cholesterol warrants caution. For healthy aging, cardiovascular risk should be considered alongside potential metabolic benefits.
Reviewed and Summarized by
Source Publication
- Title:
- Ketogenic Diet and Cardiovascular Risk: A Meta-Analysis of 27 Randomized Trials
- Authors:
- Wang Z, et al.
- Journal:
- The American Journal of Clinical Nutrition, August 2024.
