A vegetarian diet lacking meat, poultry and fish was thought to increase the risk of deficiencies. However, health benefits on body mass index, cholesterol and glucose levels and lower risk of cardiovascular disease and cancer have been demonstrated. Dental diseases are very common but is unclear whether a vegetarian diet has any impact.
The aim of this review was to assess the evidence for associations between a vegetarian diet and (a) non-carious/cervical lesions (NCCL), (b) dental caries and (c) number of natural teeth.
Methods
Searches were conducted in the PubMed, Embase, CINHAL and Web of Science databases. Observational or intervention studies comparing a vegetarian diet with a non-vegetarian diet in terms of dental health outcomes were considered. All diets excluding all meat, poultry or fish were considered as the diet of interest. The primary outcomes were NCCL, dental caries and number of natural teeth.
Two reviewers independently selected study. One review extracted data for checking by a second reviewer. Risk of bias was assessed by 2 reviewers independently using the Newcastle‐Ottawa Scale (NOS) for assessing quality of nonrandomized studies and the adapted NOS for cross‐sectional studies. Meta-analysis was performed when a dental health characteristic was reported in three or more papers in a comparable way.
Results
- 21 papers reporting on 18 studies were included.
- 16 studies were cross-sectional and 2 baseline reports from RCTs.
- 9 studies were from India, 3 from Finland, 4 from other European countries, 1 Brazil, 1 Trinidad and Tobago.
- 2 studies were considered to be of fair quality, the rest of poor quality.
- 11 studies reported on NCCL with 6 studies contributing to meta-analysis.
- The findings showed a significantly higher risk of the presence of dental erosion in vegetarians than in nonvegetarians (odds ratio (OR) = 2.40 (95%CI: 1.24 to 4.66).
- A sensitivity analysis resulted in a slightly lower but still significant effect, OR= 1.97 (95%CI: 1.19, 3.27).
- A subgroup meta-analysis (adults only) showed a higher prevalence of erosion in vegetarians OR= 2.94 (95%CI: 1.64, 5.26).
- 11 studies reported on dental caries with 4 studies contributing to a meta-analysis.
- Findings show a significantly lower mean DMFT score in vegetarians than in non‐vegetarians (mean difference (MD) = −0.15 (95%CI −0.29, −0.02).
- Sensitivity analysis (adult sonly) showed a lower and nonsignificant effect MD= −0.10 (95%CI: −0.32, 0.13).
- 7 studies reported on number of teeth reporting conflicting findings.
Conclusions
The authors concluded: –
Within the limitations of the present study, the findings suggest that following a vegetarian diet may be associated with a greater risk of dental erosion.
Comments
While a good search strategy has been employed for this review almost all of the included studies were cross-sectional in nature and none of the studies were of high quality. In addition, the authors’ note that there was very little reporting of potential confounding variables in the included studies. The findings suggest that people following a vegetarian diet may have a higher prevalence of dental erosion which may be due to an increase in fruit consumption. However, this finding needs to be interpreted cautiously because of the limited quality of the included studies. The impact of the length of time following a vegetarian diet may have an impact on the findings so well-conducted longer-term prospective studies adjusted for confounders are needed to better understand the potential impact of a vegetarian diet on dental health.
Links
Primary Paper
Smits KPJ, Listl S, Jevdjevic M. Vegetarian diet and its possible influence on dental health: A systematic literature review. Community Dent Oral Epidemiol.2019 Oct 1. doi: 10.1111/cdoe.12498. [Epub ahead of print] Review. PubMed PMID:31571246.
Other references
Dental Elf – 12th Dec 2013
Detailed review finds that restricting free sugar intake reduces caries development
Picture Credits
“Vegetables” by HatM is licensed under CC BY-NC-SA 2.0
Hi. We are going to discuss this paper in the OHS journal club next week. I see there is little discussion of the apparent conflicting result in the initial analyses: ie vegetarians showed more erosion but a lower DMFT score. Wouldn’t you expect both measures to go in the same direction, even if they are not always statistically significant?
Hi Stephen
You might anticipate caries and erosion measure going in the same direction. I think you need to bear in mind the low quality of the included studies and the smaller number of studies contributing to the meta-analyses.