Vegan Diet and Food Costs Among Adults With Overweight (2024)

Vegan diets are recognized for numerous health benefits. However, given that food costs may represent a barrier to dietary change, the costs of vegan diets merit examination.

As reported previously in a randomized clinical trial (RCT),¹ an ad libitum low-fat vegan diet resulted in weight loss, improved body composition, and increased insulin sensitivity in overweight adults. This secondary analysis of that RCT assessed food costs. As the prices of staple foods, such as rice and beans, are much lower compared with meat and dairy, it was hypothesized that food costs would be reduced on a vegan diet.

The methods have been previously described.¹ In brief, this randomized, open parallel study was conducted between January 2017 and February 2019 in Washington, DC (trial protocol in Supplement 1). This study followed the CONSORT reporting guideline. The protocol was approved by the Chesapeake institutional review board. All participants provided written informed consent.

Participants were randomly assigned to a vegan or control group in a 1:1 ratio (eFigure in Supplement 2). The vegan group was asked to follow an ad libitum low-fat vegan diet consisting of fruits, vegetables, grains, and legumes, while the control group was requested to make no diet changes. Energy intake and food costs were not limited for either group. At baseline and week 16, a 3-day dietary record (2 weekdays and 1 weekend day) was completed by each participant and analyzed by a registered dietitian certified in the Nutrition Data System for Research.²

For the food cost assessment, intakes from dietary records were linked to a database of national food prices,³ using the US Department of Agriculture Thrifty Food Plan.⁴ Two independent reviewers (C.M. and D.N.), blinded to group assignment, linked it with food groups from the dietary analysis software.² Linking accuracy was verified by a senior researcher (P.M.), also blinded to group assignment. A repeated measure analysis of variance was used by a statistician blinded to dietary interventions. All significance reporting is 2-sided with type I error of .05. Two-sample t-tests were used to assess the differences between treatment groups, and 1-sample t-tests to assess significance of changes within each group. Statistical analysis was conducted using SAS version 9.4 (SAS Institute) in May 2023.

Of 3115 people screened by telephone, 244 adults with overweight met participation criteria and were randomly assigned to the vegan (n = 122; 105 [86.1%] female; 60 [49.2%] Black; 57 [46.7%] White; mean [SD] age, 52.9 [10.3] years) or control (n = 122; 106 [86.9%] female; 53 [43.4%] Black; 60 [49.2%] White; mean [SD] age, 56.7 [12.8] years) groups. The analysis included 223 (91.0%) participants who completed all aspects of the study, including the final diet records.

Mean (95% CI) total food costs per day decreased in the vegan group by approximately 16%, compared with no significant change in the control group. The difference between the groups was significant (Figure, Table). The biggest savings were on meat and dairy. These savings outweighed the increased spending on vegetables, fruits, legumes, whole grains, meat alternatives, and dairy alternatives.

This secondary analysis of an RCT found that a low-fat vegan diet was associated with an approximately 16% decrease in total food costs. In addition to health benefits, a vegan diet may have economic advantages. A 2021 study estimated that diets including less animal and more plant foods were up to 25% to 29% less expensive than omnivorous diets.⁵ A large US Internet survey found that food expenditures for vegetarians were lower than for their meat-eating counterparts.⁶

The strengths of the current study include a randomized, parallel design, which accounted for seasonal effects. The study also has limitations. Food costs were based on self-reported diet records and did not include supplements or medications. Food cost estimates in the Thrifty Food Plan are conservative and exclude alcohol. The participants were research volunteers and may not represent the general population.

Accepted for Publication: July 27, 2023.

Published: September 5, 2023. doi:10.1001/jamanetworkopen.2023.32106

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2023 Kahleova H et al. JAMA Network Open.

Corresponding Author: Hana Kahleova, MD, PhD, Physicians Committee for Responsible Medicine, 5100 Wisconsin Ave NW, Ste 400, Washington, DC 20016 ([email protected]).

Author Contributions: Dr Kahleova had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Kahleova, Barnard.

Acquisition, analysis, or interpretation of data: Kahleova, Sutton, Maracine, Nichols, Monsivais, Holubkov.

Drafting of the manuscript: Kahleova, Maracine, Barnard.

Critical review of the manuscript for important intellectual content: Sutton, Maracine, Nichols, Monsivais, Holubkov.

Statistical analysis: Holubkov.

Obtained funding: Barnard.

Administrative, technical, or material support: Sutton, Monsivais.

Supervision: Kahleova, Sutton, Barnard.

Conflict of Interest Disclosures: Dr Barnard reported serving without compensation as president of the Physicians Committee for Responsible Medicine and Barnard Medical Center in Washington, DC (nonprofit organizations providing educational, research, and medical services related to nutrition); he also writes books and articles and gives lectures related to nutrition and health and has received royalties and honoraria from these sources. No other disclosures were reported.

Funding/Support: This work was funded by the Physicians Committee for Responsible Medicine.

Role of the Funder/Sponsor: The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Data Sharing Statement: See Supplement 3.

Additional Information: ClinicalTrials.gov Identifier: NCT02939638.