By Michael Macknin, MD
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The beneficial health effects of plant-based (PB) diets have been established in adults, but whether these benefits extend to children is not known. To shed light on this question, a team of clinician researchers from Cleveland Clinic Children’s recently conducted the first randomized trial1 to determine whether cardiovascular risk is reduced in children following a PB, no-added-fat diet compared with children following the American Heart Association (AHA) diet.
Do adult findings apply to children?
Cardiovascular disease is known to frequently begin in childhood, and the need for effective lifestyle modifications that target the growing group of obese children with dyslipidemia is clear. Studies in adults have suggested that a low-fat, vegan diet (no animal products) may promote weight loss, reduce body mass index (BMI), improve lipoprotein profiles and insulin sensitivity, and possibly prevent cardiovascular disease. Those who follow a vegetarian diet (no animal products except for dairy and/or eggs) typically have lower cholesterol levels and a lower risk for coronary heart disease than do nonvegetarians. Additionally, vegan and vegetarian diets have been shown to not only prevent but also reverse heart disease in adults.
To assess whether similar effects may be seen in children, we conducted a four-week randomized trial comparing a PB, no-added-fat diet (only plants and whole grains, limited avocado and nuts) with the AHA diet in a group of 30 children ages 9 to 18 years and one of each child’s parents. All children were obese (BMI > 95th percentile for age and sex) and had hypercholesterolemia (total cholesterol > 169 mg/dL). Similar to the PB diet, the AHA diet2 encourages fruits, vegetables, whole grains and low sodium intake but permits non-whole grains, low-fat dairy, selected plant oils, and lean meat and fish in moderation. Our aim was to determine whether either or both of these diets would significantly change anthropometric measures and/or biomarkers of inflammation and cardiovascular risk after a four-week intervention with weekly two-hour classes on nutrition education in these children at elevated risk for cardiovascular disease.
Key study findings
After the four-week intervention, statistically significant (P < .05) beneficial changes from baseline (mean decreases) were observed in 9 of 17 clinical measures assessed among children in the PB diet group and in 4 of 17 measures among children in the AHA diet group (Table). The only significant change favoring the AHA diet was a 1 percent difference in children’s waist circumference. Among parents, statistically significant (P < .05) beneficial changes from baseline were observed in seven clinical measures for those on the PB diet and in two clinical measures for those on the AHA diet.
Implications and limitations
The only significant problem in diet acceptance reported by our middle-class study population was difficulty purchasing food. Notably, cost may be an additional barrier to adherence to a PB diet in populations with lower socioeconomic status. In another study (conducted among adults), the only identified barrier to adherence was the effort required.3 If the PB diet is to achieve wider adoption, barriers to easy, affordable access to plant-based, no-added-fat foods will need to be reduced.
The major limitations of our study are its small size, short duration and restriction to middle-class subjects, as well as the use of less than completely reliable adherence measures and no direct health outcome measures. Moreover, although the AHA is considered a standard of care and was used as a comparison group, there was no placebo group.
There is also concern that long-term adherence to the PB diet could be problematic, especially given the difficulties expressed by families in finding food to purchase for the diet in our study and the efforts required to follow a PB diet in a previous study.4 At the same time, other studies describe good acceptability of and compliance with a PB diet.3,5-7
PB diets are generally recognized as safe for children and adolescents as long as the intake of key nutrients is monitored and appropriate supplements are provided. The results of our study suggest that the documented benefits of PB diets in adults — including a reduction in overweight/obesity and a decrease in cardiovascular risk — most likely would be seen in children. These benefits, especially given the known onset of cardiovascular disease in childhood, could improve the lifetime health of populations that adopt a PB diet in childhood.
Larger and longer studies now in the works
Our future research efforts are focused on answering some questions this preliminary study left unanswered. Our initial study was powered to detect within-group differences before and after intervention. The benefits of dietary intervention were so large that we were able to demonstrate many significant improvements in markers of cardiovascular risk despite studying only 30 patients with a brief four-week intervention. Our future studies are designed with sample sizes large enough to detect statistically and clinically significant differences between PB and AHA diet interventions and will also include a Mediterranean diet group.
Our future studies will also be designed to help patients easily locate the food they need to purchase for their diets, will have improved methods of measuring diet compliance, and will be at least a year in duration to help determine the sustainability and one-year effects of these diets. By simultaneously studying the three major diet types highlighted in the 2015 U.S. dietary guidelines — AHA, Mediterranean and PB — we hope to provide insight on the comparative advantages and disadvantages of these diets in children and their parents for preventing cardiovascular disease.
Portions of this article were excerpted from reference 1 (Macknin et al, Journal of Pediatrics), ©2015, with permission from Elsevier.
- Macknin M, Kong T, Weier A, Worley S, Tang AS, Alkhouri N, Golubic M. Plant-based, no-added-fat or American Heart Association diets: impact on cardiovascular risk in obese children with hypercholesterolemia and their parents. J Pediatr. 2015;166:953-959.
- American Heart Association Nutrition Committee. Diet and lifestyle recommendations revision 2006: a scientific statement from the American Heart Association nutrition committee. Circulation. 2006;114:82-96.
- Barnard ND, Scialli AR, Turner-McGrievy G, Lanou AJ. Acceptability of a very low-fat, vegan diet compares favorably to a more moderate low-fat diet in a randomized, controlled trial. J Cardiopulm Rehabil. 2004;24:229-235.
- Barnard ND, Scialli AR, Bertron P, Hurlock D, Edmonds K. Acceptability of a therapeutic low-fat, vegan diet in premenopausal women. J Nutr Educ. 2000;32:314-319.
- Esselstyn CB, Gendy G, Doyle J, Golubic M, Roizen MF. A way to reverse CAD? J Fam Pract. 2014;63:356-364b.
- Ornish D, Scherwitz LW, Billings JH, et al. Intensive lifestyle changes for reversal of coronary heart disease. JAMA. 1998;280:2001-2007.
- Barnard ND, Gloede L, Cohen J, et al. A low-fat vegan diet elicits greater macronutrient changes, but is comparable in adherence and acceptability, compared with a more conventional diabetes diet among individuals with type 2 diabetes. J Am Diet Assoc. 2009;109:263-272.
Dr. Macknin is a staff physician in the Department of General Pediatrics.