Plant-Based Diets Associated with Decreased Bone Mineral Density

by | May 16, 2023 | 2023, Bone Health, Vegetarianism

Written by Taylor Woosley, Staff Writer. Plant based diets were associated with increased risk of bone loss, while higher unhealthy plant-based diets were associated with increased risk of osteoporosis. 

plate of vegetables and riceOsteoporosis is a systemic skeletal disease characterized by low bone mass, the deterioration of the microarchitecture of bone tissue, and a consequent increase in bone fragility1. Annually, osteoporosis contributes to 8.9 million fractures worldwide, as well as reduced physical and psychological health, lower quality of life, and shorter life expectancy2. The disease has many causes, including age, genetic factors, and hormone imbalance, and mainly occurs in postmenopausal women and older men aged >50 years3.

Furthermore, diet is considered a leading cause of bone mineral density loss4. Plant-based diets, which focus on a higher intake of plant foods and a reduction in animal foods, could possibly lead to a deficiency in specific nutrients such as calcium and vitamin D, thus leading to bone loss and osteoporosis5. Additionally, previous research has found that those following a plant-based diet exhibit lower bone mass density (BMD) and higher rates of fractures in the femoral neck and lumbar spine than those following an omnivorous diet6.

Zheng et al. conducted a cross-sectional designed study to investigate the potential relationship between plant-based dietary indexes and osteopenia/osteoporosis in the adult population of the United States. Data used in the study was from the National Health and Nutrition Examination Survey (NHANES), with subject information from five 2-year NHANES cycles (2005-2006, 2007-2008, 2009-2010, 2013-2014, and 2017-2018). Subject inclusion consisted of being aged ≥20 years, with a complete BMD and dietary interview data, with available reported energy intake levels within predefined limits. A total of 16,085 participants were included in the study.

Participants underwent BMD measuring at the lumbar spine and the femoral neck using a dual-energy X-ray absorptiometry densitometer. Dietary intake data was collected and estimated using two NHANES 24-h recall interviews. The three plant-based diet indexes (PDI) were assessed based on the intake of 15 food groups, which were divided into three categories: healthy plant-based foods (hPDI), unhealthy plant-based foods (uPDI), and animal-based foods. Covariates such as subjects’ demographical characteristics, body mass index, poverty income ratio (PIR), and history of disease were considered in the study.

Categorical variables were described by the percentage of participants and chi-square test was used to compare the differences between groups. Spearman’s correlation coefficients were utilized to measure the associations between the three plant-based diet indexes and the BMD T-score. Multinomial logistic regression analysis was applied to observe the relationship between the three plant-based diet indexes and different BMD statuses. Of the 16,085 subjects, 8238 (51.22%) were female, and 4631 (28.79%) were over 65 years of age. The three groups significantly differed in age, sex, ethnicity, education, PIR, BMI, smoking status, physical exercise, history of disease, history of fracture, hPDI, PDI, and uPDI (p < 0.05). Significant findings of the study are as follows:

  • In the fully adjusted model, subjects in the highest quintile for both hPDI (ORQ5 Q1 = 1.50; 95% CI: 1.24–1.81) and PDI (ORQ5 vs. Q1 = 1.22; 95% CI: 1.03–1.45) had a positive association with osteopenia compared with participants in the lowest quintile, while the highest uPDI (ORQ5 vs. Q1 = 1.48; 95% CI: 1.04–2.11) was positively associated with osteoporosis.
  • Comparing the differences in the association between the three PDIs and different BMD statuses in the femoral neck and lumbar spine show that, for the lumbar spine, hPDI (ORQ5 vs. Q1 = 1.25; 95% CI: 1.03–1.51; ORper 10-unit increment = 1.11; 95% CI: 1.02–1.21) and PDI (ORQ5 vs. Q1 = 1.33; 95% CI: 1.07–1.67; ORper 10-unit increment = 1.22; 95% CI: 1.03–1.45) were also proved to be risk factors for osteopenia, while uPDI was found to be a risk factor for both osteopenia (ORQ2 vs. Q1 = 1.23; 95% CI: 1.01–1.50) and osteoporosis (ORQ5 vs. Q1 = 1.58; 95% CI: 1.04–2.39; ORper 10-unit increment = 1.31; 95% CI: 1.09–1.58).

Results of the study show that adherence to a plant-based diet is associated with decreased bone mineral density. Furthermore, a negative association was found between hPDI and PDI and osteopenia, which was more significant at the lumbar spine compared to the femoral neck. Study limitations include the design of the study which does not allow for establishing a causal relationship between plant-based diets and osteopenia/osteoporosis and the potential inaccuracy of dietary intake recalls.

Source: Zheng, Yi, Jiacheng Wang, Yawen Wang, Kelin Xu, and Xingdong Chen. “The Hidden Dangers of Plant-Based Diets Affecting Bone Health: A Cross-Sectional Study with US National Health and Nutrition Examination Survey (NHANES) Data from 2005–2018.” Nutrients 15, no. 7 (2023): 1794.

© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). 

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Posted May 16, 2023.

Taylor Woosley studied biology at Purdue University before becoming a 2016 graduate of Columbia College Chicago with a major in Writing. She currently resides in Glen Ellyn, IL.

References:

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