Table 3. Data extraction table.

Authors	Study Design and sample size	Population	Intervention or exposure	Type of supplement intake	Outcomes	Main findings	Comparison	Limitations
Willershausen et al., 2011	Randomized Controlled Trial	Dental students(n=42) Mean age – 27.1 ± 3.0 years	Dietary supplements	Orthomol vital f/m; ortho- mol pharmazeutische Vertriebs GmbH.	Dental Assessment Microbiological Analysis Blood Analysis Dietary habits	The group with intake of nutritional supplements had a slight positive effect with lesser increase in C-reactive protein (CRP) levels as compared to the control group. Increase in vitamin C and E and zinc concentration in the blood was observed in the group receiving the nutritional supplement.	_	Small sample size and shorter duration of time.
Adegboye et al., 2013	Cross sectional study	Adult population above 65 years of age (n=606)	Not applicable	Calcium Vitamin D	Oral Examination including number of teeth, unstimulated salivary flow, and plaque score.	There was a significant reduction in plaque score among individuals with higher calcium and dairy servings among those with higher vitamin D intake, after the adjustment for education, gender, age, intakes of sucrose, alcohol and minerals, smoking, number of teeth, diseases, use of dental floss/toothpicks, and visits to the dentists.	_	Higher dropout rates from the original cohort and exclusion due to insufficient data. Lacking detailed data regarding supplemental calcium intake.
Dodington et al., 2015	Cross sectional study	Patients with chronic generalized periodontitis (63 non-smokers, 23 smokers) who were being treated with scaling and root planing participated.	Not applicable	Fruits, Vegetables, β-carotene, Vitamin C, α-tocopherol, Eicosapentaenoic acid (EPA) Docosahexaeboic acid (DHA), α-linolenic acid (ALA), serum 25-hydroxy vitamin D concentrations.	Probing depth and bleeding on probing.	Probing depth was significantly reduced with intake of fruits and vegetables, α-tocopherol, vitamin C, β-carotene, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) intakes in nonsmokers while smokers showed no association.	Smokers and non-smokers.	Small sample size. Self-reported dietary assessment method.
Luo et al., 2018	Cross sectional study	The National Health and Nutrition Examination Survey (NHANES) participants aged more than 30 years with complete periodontal examination	Not applicable	Micronutrients in diet including vitamins A, B1, B2, B6, B12, C, D, E, folate, iron, zinc, calcium, phosphorus, and caffeine.	Periodontal disease and severity.	Severity of periodontal disease increased with decreased intake of Vitamins A, B1, C, E, iron, folate and phosphorus. Second highest level of vitamin D intake was associated with decreased severity of periodontal disease in comparison with highest level of Vitamin D intake.	_	Generalizability of results as NHANES dataset is representative of US population and dietary recall as a method maybe lacking for knowledge of micronutrients.