The objective of the present study was to investigate the association between salivary counts of mutans streptococci (MS) and children’s weight status, while considering associated covariates. MS ferments carbohydrates from the diet and contributes to caries by lowering the pH in dental plaque. In adults, high counts of MS in saliva have been associated with overweight, but this has not been shown in children.

Cross-sectional study investigating salivary counts of MS, BMI Z-score, waist circumference, meal frequency, sugar propensity and sleep duration, in children.

West Sweden.

Children (n 271) aged 4–11 years.

Medium–high counts of MS were positively associated with higher BMI Z-score (OR=1·6; 95 % CI 1·1, 2·3). Positive associations were also found between medium–high counts of MS and more frequent meals per day (OR=1·5; 95 % CI 1·1, 2·2), greater percentage of sugar-rich foods consumed (OR=1·1; 95 % CI 1·0, 1·3) and female sex (OR=2·4; 95 % CI 1·1, 5·4). A negative association was found between medium–high counts of MS and longer sleep duration (OR=0·5; 95 % CI 0·3, 1·0).

BMI Z-score was associated with counts of MS. Promoting adequate sleep duration and limiting the intake frequency of sugar-rich foods and beverages could provide multiple benefits in public health interventions aimed at reducing dental caries and childhood overweight.

To study associations between reported sugar intake and salivary bacteria (mutans streptococci, MS and lactobacilli, LB), and sugar intake in relation to body mass index (BMI), in women and adolescents.

Cross-sectional study. Habitual dietary intake was reported in a questionnaire and whole saliva samples were collected and cultivated.

Stockholm, Sweden.

Four hundred and fourteen mothers and their 16-year-old children (57% girls).

Reported total sugar intake was significantly associated with LB in mothers (P = 0.001), but not in daughters and sons (P = 0.03 for mother–son interaction). When excluding lactose, the associations with LB and MS were significant in daughters (P = 0.032 and 0.005, respectively). High BMI and sugar intake from milk were independently associated with MS counts in mothers in a multiple regression model (R2 = 0.053). In daughters, sugar from beverages, candies/chocolates and fruits were all independently associated with MS counts (R2 = 0.074), whereas in sons, only mothers’ MS counts were associated (R2 = 0.084). High BMI, low intake from cooked meals and high intake of candies/chocolates were all independently associated with LB in mothers (R2 = 0.076), while, except for candies/chocolates in daughters, no significant associations were found in children. BMI was significantly associated with bacteria counts in both mothers and children, whereas reported sugar intake was not.

The associations between reported sugar intake and bacteria were generally weak. In mothers and daughters, some significant associations were found, but not in sons. Bacteria counts, but not reported sugar intake, were positively associated with BMI.