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Evidence Summary

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The Paleo diet may reduce weight, waist circumference, BMI, and body fat percentage in adults, but overall more research is needed to draw firm conclusions on its effect on risk factors for cardiovascular disease   

Ghaedi E, Mohammadi M, Mohammadi H, et al. Effects of a paleolithic diet on cardiovascular disease risk factors: A systematic review and meta-analysis of randomized controlled trials Adv Nutr. 2019;10:634-646.

Review question

What is the effect of the Paleo diet on risk factors for cardiovascular disease (CVD)? 

Background

Thirty percent of deaths that occur globally are related to some type of CVD, making this group of conditions the leading cause of death worldwide. Past research, looking mainly at certain foods/food groups/nutrients, has demonstrated that diet may greatly influence the occurrence of CVD. But research on this link and specific diets, as a whole, is lacking. The Paleolithic diet or Paleo diet recommends avoiding dairy, grains, added sugar and salt, and processed foods, while favoring the consumption of nuts, eggs, lean meat, fruits, fish, and vegetables. This diet mirrors the food consumption patterns of hunter-gatherers in the Old Stone Age. The current evidence base around the Paleo diet and its impact on risk factors for CVD and diabetes is inconsistent, requiring further research on the topic.

How the review was done

This is a systematic review and meta-analysis of eight randomized controlled trials published between 2009 and 2017, including a total of 266 participants.

  • Participants were on average 53 years old. The health status of participants varied; some were classified as healthy, while others had type 2 diabetes, multiple sclerosis, heart disease, or conditions that increase the risk for heart disease and diabetes.
  • Study participants followed the Paleo diet.
  • Researchers measured changes in weight, waist circumference, body mass index (BMI), body fat percentage, systolic and diastolic blood pressure, the concentrations of different types of fat found in the blood—such as LDL cholesterol or ‘bad cholesterol’, HDL cholesterol or ‘good cholesterol’, total cholesterol, and triglycerides—and the concentrations of C-reactive protein [CRP] (a marker for inflammation).
  • Results were compared to people in control groups who either stayed on their usual diet or followed another diet—such as a Mediterranean-like diet—or dietary recommendations—such as the Nordic Nutrition Recommendations, American Diabetes Association guidelines, and Australian Guide to Healthy Eating.

What the researchers found

The Paleo diet was effective in reducing weight, waist circumference, BMI, body fat percentage, systolic and diastolic blood pressure, LDL cholesterol, total cholesterol, triglycerides, and CRP in adults, compared to control diets. It was also effective in increasing HDL cholesterol. However, it should be noted that when certain studies were removed from the analysis, the positive effect of the Paleo diet on blood pressure, LDL cholesterol, HDL cholesterol, total cholesterol, triglycerides, and CRP was no longer present. This means that the results for these outcomes need to be interpreted carefully. Overall, more high quality long-term studies, which include many more participants, are needed in order to make firm conclusions about the relationship between the Paleo diet and CVD risk factors. The current review was hindered by the small number of participants across studies, as well as differences in the participants’ health status, how long they were on the Paleo diet for, and what type of diet was used as the comparison. 

Conclusion

In adults, the Paleo diet may improve certain risk factors for CVD, such as weight, waist circumference, BMI, and body fat percentage. Despite these promising results, more research is needed to make definitive conclusions on this diet’s impact on risk factors for CVD.  




Glossary

Control group
A group that receives either no treatment or a standard treatment.
Diastolic
The lower number in a blood pressure reading. It is the pressure when the heart rests between beats.
Meta-analysis
Advanced statistical methods contrasting and combining results from different studies.
Randomized controlled trials
Studies where people are assigned to one of the treatments purely by chance.
Risk factors
Aspects making a condition more likely.
Systematic review
A comprehensive evaluation of the available research evidence on a particular topic.
Systolic
The higher number in a blood pressure reading. It is the pressure in the arteries when the heart beats.
Vascular
The body's network of blood vessels. It includes the arteries, veins, and capillaries that carry blood to and from the heart.

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