Journal of Osteoporosis Table 1: Characteristics of the study sample (n = 2126). Age group (years) 30 40 + 45 59–60 Men n = 246a n = 396a n = 229a Body weight (kg) 82.7 (12.4)b 83.5 (13.1) 82.6 (12.3) Height (cm) 180.2 (7.5) 178.1 (11.0) 175.7 (12.6) BMD (g/cm2) 0.57 (0.04) 0.56 (0.05) 0.53 (0.06) Dietary Indexc 0.38 (0.20) 0.32 (0.19) 0.25 (0.14) (i) Colas 2.20 (1.05) 1.90 (1.01) 1.55 (0.92) (ii) Non-colas 1.84 (0.74) 1.65 (0.87) 1.45 (0.73) (iii) Fruit/berries 3.38 (1.15) 3.51 (1.22) 3.78 (1.14) (iv) Cooked vegetables 2.81 (0.99) 3.10 (0.94) 3.51 (0.94) (v) Raw vegetables 3.06 (0.96) 3.19 (1.02) 3.32 (1.09) (vi) Fruit juice 2.30 (0.96) 2.10 (0.92) 2.08 (0.89) Education (years) 15 (3) 14 (4) 13 (4) Daily smokers (%) 26.8 34.7 27.0 Use of alcohol 1 to 7 Times per week (%) 55.9 57.4 65.2 PA (%)d (i) No activity 6.0 9.6 8.2 (ii) <1 h/wk 12.0 14.1 11.4 (iii) 1-2 h/wk 29.6 26.6 25.4 (iv) ≥3h/wk 52.4 49.7 55.0 Women n = 212a n = 415a n = 628a Body weight (kg) 67.8 (13.0)b 68.3 (11.8) 69.9 (12.3) Height (cm) 165.8 (16.3) 165.2 (12.6) 164.9 (8.6) BMD (g/cm2) 0.46 (0.04) 0.46 (0.05) 0.43 (0.06) Dietary Indexc 0.28 (0.13) 0.25 (0.13) 0.21 (0.10) (i) Colas 1.86 ( 0.86) 1.63 (0.91) 1.31 (0.69) (ii) Non-colas 1.57 (0.66) 1.44 (0.67) 1.30 (0.58) (iii) Fruit/berries 4.04 (1.20) 4.03 (1.19) 4.36 (1.14) (iv) Cooked vegetables 3.03 (0.96) 3.26 (1.00) 3.59 (0.90) (v) Raw vegetables 3.50 (0.99) 3.62 (1.04) 3.46 (1.00) (vi) Fruit juice 2.35 (0.88) 2.06 (0.83) 1.97 (0.89) Education (years) 16 (4) 14 (4) 12 (4) Daily smokers (%) 22.4 32.0 23.1 Use of alcohol 1 to 7 Times per week (%) PA (%)d (i) No activity (ii) < 1 h/wk (iii) 1-2 h/wk (iv) >3 h/wk 31.8 3.4 10.3 20.6 65.7 57.4 7.5 8.7 31.1 52.7 54.9 4.9 10.0 34.2 56.0 a The number may vary slightly due to missing data. bMean values, SD in parentheses. cSum of intake frequency estimates of 2 diet items (colas and non-cola soft drinks) divided by the sum of intake estimates of 4 items (fruit/berries, cooked vegetables, raw vegetables/salads, and fruit juice). There were 5 response alternatives for beverages and 6 for the food items (see Section 2); mean intake estimate of each index component was calculated as the mean of all levels, neglecting the variations in unit (rarely/never, times per month, week or day; see Section 2. dLeisure time physical activity, % of subjects. BMD = distal forearm bone mineral density (g/cm2). 3 The variable was dichotomized into those drinking 1–7 times per week versus those drinking less frequent. Physical activity was measured by a question about hours per week of light physical activity during leisure time the previous year, including going to/from work. The categories were 0, <1, 1- 2, 3 or more hours per week. 2.7. Statistical Methods. Linear regression was used to eval- uate the association between intake frequency estimates of various single food items, the Dietary Index, and bone min- eral density at the distal forearm. The distribution of bone mineral density (BMD) was fairly normal (not shown). We ﬁrst studied the association between some single food items supposed to inﬂuence the acid load and BMD, adjusting for gender, age, body mass index, length of education, smoking, alcohol intake, and leisure time physical activity. The regression analyses were performed with one by one of the items of food/beverages as main independent variable. We then did the same analysis with all the food/beverage items entered simultaneously in the model. Each item was adjusted for all the other items and the covariates. Next, we studied the association between the Dietary Index and BMD, in several Models: (1) adjusting for gender and age only, (2) the preceding + body weight + body height, (3) the preceding + years at school, and (4) the preceding + smoking + alcohol + leisure time physical activity. We also used Model (4) to analyze the association between BMD and the Dietary Index in women and men separately. Finally, the number of components in the index was reduced by omitting one by one of its components in linear regression models, examining the inﬂuence of this procedure on the association between the various new indexes and BMD. A signiﬁcance level of 0.05 was accepted. SPSS 15.0 was used for the analyses. 3. Results 3.1. Characteristics of the Study Population. Table 1 shows the percentage or mean (SD) for the variables used in this study, by age and gender. In all age groups, the Dietary Index was higher for men than women, and the index decreased with increasing age. 3.2. Intake of Single Food Items/Beverages and Distal Forearm BMD. When we entered the food items one by one, cola and non-cola soft drinks were negatively associated with distal forearm BMD, whereas intake of raw vegetables was positively associated, when the covariates were adjusted for (Table 2). However, entered simultaneously, none of the items showed a statistically signiﬁcant association with distal forearm BMD. Stratiﬁed analyses on gender gave similar results, with the exception that intake of cooked vegetables showed a negative association (P = .039) in men (results not shown). 3.3. The Dietary Index and Distal BMD. There was a sig- niﬁcant inverse relationship between the Dietary Index and distal BMD when adjusting for gender and age (Table 3, Model (1)). Subsequently, we adjusted for an increasing