# Abstract

 

## Background The effect of dietary calcium on fecal fat excretion in lactose maldigestion is not known. 

## Objective To investigate the effect of dairy and nondairy dietary calcium on fecal fat excretion in lactose digesters and maldigesters during moderate energy restriction. 

## Design A randomized cross-over trial comparing the effect of 500 mg vs. 1500 mg dairy and nondairy calcium on fecal fat excretion in 34 healthy adults during moderate (− 30%) energy restriction diet-induced weight loss for 12 weeks. The participants were classified as lactose digester or maldigester on the basis of breath hydrogen test. 

## Measurements Anthropometric parameters and body composition, resting energy expenditure, energy and nutrient intake, fecal fat, physical activity, blood pressure, blood and urine sampling for pertinent measurements. 

## Results Fecal fat loss expressed as percent of fat intake was significantly higher with 1500 mg (high-Ca) compared to 500 mg (low-Ca) calcium intake per day (mean: 3.0%; the 95% CI: 2.3 to 3.7%; *P* \<0.001) independent of calcium source and lactose digestion status. 

## Conclusions During moderate energy restriction induced weight loss a high-Ca diet causes an increase in fecal fat excretion independent of calcium source. Calcium intake related fecal fat loss is also independent of the ability to digest lactose and it is not diminished over time. # RESULTS A total of 51 volunteers were recruited for the study, 40 were randomized, and 34 completed the study (19 Caucasians, 11 African Americans, and 4 declaring other ethnicities). One participant was dropped due to noncompliance, and five withdrew between week 1 and week 8. Baseline and end of the study characteristics of participants who completed the study are shown in [Table 1](#). There was no difference in initial weight and body composition between lactose maldigesters and digesters and between dairy and nondairy diets (all *P* >0.05). 

## Dietary intake and compliance with the study diets The participants had an average energy intake of 7.5 ± 1.5 MJ ([Table 2](#)). The average intake of energy from carbohydrates, fat, and protein was 54.5 ± 3.0%, 28.9 ± 2.6%, and 18.4 ± 1.85%, respectively. There were no differences between macronutrient and fiber content between the diets (dairy vs. nondairy). Average amount of calcium in low-Ca and high-Ca diets was 503 ± 73 and 1491 ± 131 mg/day, respectively and the level was not different between dairy and nondairy diets. There were no significant differences between the intake of protein, sodium, and potassium and their respective biological markers in weekly urine collections. Ratio of nitrogen in urine and corresponding protein intake were not significantly different between the dairy and nondairy diets (1.13 ± 0.41 and 1.01 ± 0.14, *P* = 0.105). There were also no differences between the ratios of reported intake and excretion between dairy and nondairy diets for sodium (0.96 ± 0.20 and 0.95 ± 0.19, *P* = 0.917) and potassium (1.15 ± 0.23 and 1.12 ± 0.16, *P* = 0.684). 

## Fecal fat excretion The average fecal fat loss ([Table 3](#)) over 6 weeks was significantly higher with high-Ca diet than that with low-Ca diet after adjusting for gender, lactose digestion status, and dairy or nondairy diet source (mean: 3.0%; the 95% confidence interval (CI): 2.3 to 3.7%; *P* < 0.001). The fecal fat loss increased correspondingly with cross-over to high-Ca diet and vice versa ([Figure 1](#)). It was also significantly higher in females than that in males after adjusting for calcium intake level, lactose digestion status, and dairy or nondairy diet source (mean: 2.0%; the 95% CI: 1.2 to 2.9%; *P* < 0.001). There was no significant difference in fecal fat loss between lactose digesters and maldigesters ([Figure 2](#)) after adjusting for gender, calcium intake level, and dairy or nondairy diet source (mean: 0.2%; the 95% CI: −0.5 to 1.0%; *P* = 0.544). There was a significant positive correlation between calcium intake and fecal fat excretion in dairy (r = 0.460) and nondairy (r = 0.555) diets and in lactose digesters (r = 0.562) and maldigesters (r = 0.463, all *P* >0.05). Although not statistically significant, the average fecal fat loss over 12 weeks was higher in nondairy than that in dairy diet group ([Figure 1](#)) after adjusting for calcium intake level, lactose digestion status and gender (mean: 0.5%; the 95% CI: −0.2 to 1.2%; *P* = 0.150). In females, the average fecal fat loss over 6 weeks tended to be higher with the non-dairy than that with the dairy diet after adjusting for calcium intake level and lactose digestion status (mean: 0.8%; the 95% CI: −0.1 to 1.6%; *P* = 0.067). 

## Urinary calcium excretion Urinary calcium excretion ([Table 4](#)) was significantly higher in high-Ca than low-Ca (128.3± 57.9 and 146.4 ± 77.9 mg/day^−1^; the 95% CI for difference: 3.8 to 31.1 mg/day; *P* = 0.014). The differences in calcium excretion were not different between dairy vs. nondairy diets and in digesters vs. maldigesters (all *P* > 0.05). 

## Body weight and body composition After following an energy restricted diet for 12 weeks ([Table 1](#)), there were no significant differences in weight loss between dairy and nondairy diets (8.5 ± 2.7 and 7.2 ± 2.8 kg, *P* = 0.116). However, there were significant differences in weight changes in lactose digesters vs. maldigesters (9.2 ± 2.2 and 6.6 ± 2.4, *P* = 0.003). There was also significant differences between first and second 6-week study periods (5.6± 1.8 and 2.8 ± 1.7 kg, *P*= 0.001). The differences between dairy and nondairy diets were not significant during the first 6-week (5.7 ± 1.9 and 5.5 ± 1.7 kg) or second 6-week (2.9 ± 1.9 and 2.9 ± 1.8 kg) periods. There were also no significant differences in body fat changes across groups, dairy vs. nondairy (5.4 ± 1.5 and 4.1 ± 1.5; *P* = 0.393) or lactose digesters vs. maldigesters (5.5 ± 1.3 vs. 4.8 ± 1.7; *P* = 0.206). There were also no differences in the amount of total body water between the groups. 

## Resting energy expenditure (REE) and physical activity There was a difference in REE between the baseline and the end of the study (7.31±1.31 vs. 6.74 ± 1.32 MJ) which became insignificant when REE was adjusted for fat free mass and fat mass (data not shown). There were not REE differences between digesters and maldigesters ([Table 6](#)). The differences in the amount of physical activity measured using RT3 accelerometers during the entire study were also not significant. Participants did not change physical activity level (PAL) during the study ([Table 6](#)). 

## Blood pressure and blood parameters Diet had no significant effect on either systolic or diastolic blood pressure ([Table 7](#)). Basic hematological parameters were not different between groups (data is not shown). Diet did not have an effect on serum concentrations of insulin and vitamin D. Leptin levels decreased significantly after 12-week on the study diet independent of diet and lactose digestion status (40.6 ± 20.3 vs. 27.3 ± 16.7 ng/ml, *P* = 0.001, paired t-test). <figure> <p><img src="" /></p> <figcaption>Patterns of individual and mean fecal fat excretion with high and low calcium crossover for dairy and nondairy diets</figcaption> </figure> <figure> <p><img src="" /></p> <figcaption>Mean fecal fat excretion in lactose digesters and maldigesters with high and low calcium diets</figcaption> </figure> ::::table-wrap

::: caption
Participant Characteristics at the baseline and after 12-week of energy
restriction diet.
:::

```
                             Baseline                        After 12-week Diet                                                  
```

______________________________________________________________________

Digester (n=18) Maldigester (n=16) Digesters (n=18) Maldigesters (n=16)\
Weight (kg) 105.2 ± 11.9 (80.2 -- 124.3) 105.2 ± 17.1 (74.0 --131.2) 96.00 ± 10.8[a](#) (72.3 --113.2) 98.65 ± 16.9[a](#) (67.9 -- 128.7)
Body mass index (kg/m^2^) 35.4 ± 3.6 (28.9 -- 42.1) 36.1 ± 4.9 (28.9 -- 45.6) 32.3 ± 3.3[a](#) (25.6 -- 38.2) 34.2 ± 4.9[a](#) (26.5 -- 41.3)
Body fat mass (kg) 45.0 ± 7.8 (32.0 -- 62.9) 47.4 ± 11.1 (26.8 -- 60.9) 39.6 ± 7.8[a](#) (27.3 -- 58.4) 42.6 ± 12.1[a](#) (19.8 -- 58.3)
Total Body water (l) 48.1 ± 10.1 (36.6 --68.4) 47.1 ± 10.5 (36.6 --68.4) 44.8 ± 9.6[a](#) (32.9 --61.7) 43.8 ± 9.6[a](#) (30.4 --65.2)
Waist Circumference (cm) 107.9 ± 10.2 (90 --132) 106.2 ± 13.3 (87 --134) 101.2 ± 9.6[a](#) (84 --123) 104.2 ± 14.6[a](#) (84 --127)
Bone mineral density (g/cm2) 1.319 ± 0.105 (1.149 --1.542) 1.355 ± 0.107 (1.212 --1.628) 1.302 ± 0.096 (1.137 --1.486) 1.321 ± 0.096 (1.145 --1.526)

All values are mean ± s.d.. Values in parentheses are ranges.

significantly different from baseline, (p\<0.05, paired t-test):::: ::::table-wrap
::: caption
Average daily intake of energy, macronutrients, fiber, vitamin D, and
calcium in study participants.
:::

Diet[a](#) Energy (MJ) Fats (% energy) Carbohydrates (% energy) Proteins (% energy) Fiber (g) Vitamin D (mcg) Calcium (mg)

______________________________________________________________________

Dairy Diet (n= 17)\
Low Calcium (6 weeks) 7.47±1.4 29.3±2.6 54.1±3.2 18.5±1.6 19.0±3.9 2.29±1.3 515±69
High Calcium (6 weeks) 7.55±1.3 27.8±2.3 53.0±2.4 21.3±2.2 16.7±3.4 5.8±2.0 1488±131
Total diet (12 weeks) 7.51 ±1.3 28.6±2.5 53.5±2.8 27.8±2.3 19.9±1.9 4.0±1.66 1002±100

Non-Dairy Diet (n = 17)\
Low Calcium (6 weeks) 7.46±1.5 29.1±2.8 54.3±3.4 18.2±2.1 18.4±3.9 1.6±0.9 491±77
High Calcium (6 weeks) 7.52±1.5 28.7±2.4 54.7±2.7 18.6±1.6 18.8±4.1 3.9±1.9 1495±136
Total diet (12 weeks) 7.49 ± 1.5 28.9±2.6 54.5±3.0 18.4±1.8 18.6±4.0 2.7±1.4 992±106

All values are mean ± s.d..

Crossover design with high-Ca diet (1500 mg/day) and low-Ca diet (500
mg/day) administered in random order for 6 weeks (total 12 weeks). The
nutrient content was estimated using NDS-R dietary assessment software
(NDS, St. Paul, Minnesota, US).:::: ::::table-wrap
::: caption
Comparison of reported average (12 weeks) intake of protein, sodium, and
potassium with the corresponding biological markers in urine.
:::

```
                  Intake[a](#)                  Urinary Excretion[b](#)        Ratio of intake to excretion   P-value[c](#)
```

______________________________________________________________________

Protein (g/day) 85.0 ± 12.0 (64.7 -- 114.6) 87.9 ± 323.6 (43.0 -- 132.9) 1.04 ± 0.32 (0.67 -- 2.10) 0.496
Sodium (g/day) 3.03 ± 0.44 (2.21 -- 4.01) 3.28 ± 0.83 (1.68--4.97) 0.96 ± 0.19 (0.57 -- 1.46) 0.246
Potassium (g/day) 2.83 ± 0.43 (2.01 -- 3.81) 2.53 ± 0.53 (1.74 -- 3.58) 1.13 ± 0.19 (0.94 -- 1.68) 0.432

Data are presented as means ± s.d. Values in parentheses are ranges.

Average daily reported intakes of protein, sodium, and potassium
assessed by NDSR (Nutrition Diet System, St. Paul, MN).

Nitrogen in 24 h urine (12 weekly collections) multiplied by 7.72
(Bingham and Cummings, 1985), potassium in urine divided by 0.77
(Johansson et al, 1992).

P-values are comparisons of reported intakes of protein, sodium, and
potassium with the respective urinary excretion analyzed using the
paired t-test.:::: ::::table-wrap
::: caption
Dietary intake and fecal excretion of total fat
:::

```
                         Low-Ca diet                         High-Ca diet                                                                                                     
```

______________________________________________________________________

Fat intake[a](#) (g/day) Fecal fat excretion[b](#) (g/day) % of fat intake Fat intake[a](#) (g/day) Fecal fat excretion[b](#) (g/day) % of fat intake\
Digesters (n=18) 58.2 ± 10.4 (38.7 -- 82.8) 3.8 ± 0.7 (2.5 -- 5.2) 6.8 ± 1.8 (3.1 -- 9.2) 57.9 ± 9.3 (42.9 -- 76.3) 5.8 ± 1.0 (3.6 -- 7.1) 10.2 ± 1.5 (7.1 -- 12.6)
Maldigesters (n= 16) 56.6 ± 10.8 (38.2 -- 79.4) 4.4 ± 0.8 (2.8 -- 6.1) 7.9 ± 1.7 (4.8 --11.3) 56.7± 12.4 (36.1 -- 83.1) 5.9 ± 1.4 (4.1 -- 8.7) 10.5 ± 2.1 (5.6 --14.0)

Data are presented as means ± s.d. Values in parentheses are ranges.

Average daily reported intake of fat assessed by NDS-R (Nutrition Diet
System, St. Paul, MN).

Average daily fat excretion in 24-h stool (12 weekly collections). % of
fat intake was calculated as a % ratio of weekly fat excretion to
average weekly fat intake.:::: ::::table-wrap
::: caption
Comparison of reported daily average calcium intake and urinary calcium
excretion during 12 week diet
:::

```
                         Low-Ca diet                 High-Ca diet                                                                                                             
```

______________________________________________________________________

Ca intake[a](#) (mg/day) Urinary Ca[b](#) (mg/day) % of intake Ca intake[a](#) (mg/day) Urinary Ca[b](#) mg/day % of intake\
Digesters (n=18) 504.3 ± 36.8 (429 -- 561) 141.2 ± 47.3 (48.9 -- 222.8) 26.6± 12.1 (13.1 -- 46.1) 1498.9 ± 33.8 (1397 -- 1543) 160.9 ± 69.5 (54.8 -- 295.6) 10.9 ± 6.1 (6.1 -- 17.8)
Maldigesters (n=16) 500.1 ± 32.8 (405 --544) 115.9 ± 54.6 (39.9 -- 248.7) 23.7± 7.0 (7.0 -- 40.7) 1508.8 ± 72.5 (1424 -- 1756) 130.9 ± 85.5 (24.1 -- 365.6) 8.9 ± 7.3 (4.6 -- 17.1)

Data are presented as means ± s.d. Values in parentheses are ranges for
weekly averages.

Average daily reported intake of calcium assessed using NDSR software
(Nutrition Data System, St. Paul, MN).

Average daily calcium excretion in 24 h urine calculated from 12 weekly
collections.:::: ::::table-wrap
::: caption
Resting energy expenditure, physical activity and physical activity
level
:::

```
                                          Baseline                     After 12-Week Diet                                             
```

______________________________________________________________________

Digesters (n=18) Maldigesters (n=16) Digesters (n=18) Maldigesters (n=16)\
Resting energy expenditure (MJ/day)[b](#) 7.38 ± 1.3 (5.53 -- 9.64) 7.25 ± 1.4 (5.09 -- 9.97) 7.05 ± 1.4[a](#) (4.42 -- 9.87) 6.38 ± 1.2[a](#) (4.20 -- 8.71)
Physical activity (MJ/day)[b](#) 3.40 ± 1.5 (1.98 -- 6.28) 3.19 ± 1.2 (1.63--5.58) 2.81 ± 1.2[a](#) (0.99 -- 4.71) 2.85 ± 1.2[a](#) (1.32 -- 5.38)
Physical activity level (PAL) 1.46 ± 0.25 (1.17 -- 2.04) 1.44 ± 0.14 (1.24 -- 1.77) 1.42 ± 0.17 (1.14 -- 1.69) 1.41 ± 0.19 (1.22 -- 1.89)

Data are presented as means ± s.d. Values in parentheses are ranges.

significantly different from baseline values (P\<0.05, paired t-test).

Measured values (see the text for description of the methods). PAL is a
ratio of total energy expenditure (resting energy expenditure plus
physical activity) and resting energy expenditure.:::: ::::table-wrap
::: caption
Changes in blood pressure, hormones, and glucose
:::

______________________________________________________________________

```
                                Baseline                    After 12-Week Diet                                             
```

______________________________________________________________________

Digesters (n=18) Maldigesters (n=16) Digesters (n=18) Maldigesters (n=16)

Systolic blood pressure (mmHg) 127.5 ± 10.5 (111 -- 145) 129.7 ± 16.1 (107 --172) 124.6 ± 10.3 (95 -- 155) 123.9 ± 13.6 (100 -- 146)

Diastolic blood pressure (mmHg) 76.3 ± 11.7 (54 -- 97) 75.1 ± 8.01 (60 -- 89) 73.2 ± 7.3 (63 -- 84) 75.4 ± 10.1 (64 -- 95)

Vitamin D (ng/mL) 38.9 ± 14.5 (19 -- 65) 39.4 ± 16.5 (22 -- 66) 40.0 ± 13.41 (21 -- 64) 37.3 ± 14.8 (14 -- 64)

Parathormone (ng/L) 40.1 ± 17.9 (19 --81) 45.5 ± 15.7 (21 -- 71) 34.8 ± 13.4 (16 -- 73) 33.7 ± 10.9[a](#) (14 -- 42)

Insulin (uU/ml) 19.7 ± 17.7 (6.1 -- 74.7) 26.2 ± 22.1 (6.1 -- 80.7) 21.6 ± 17.6 (6.6 -- 70.1) 31.8 ± 28.6 (9.0 -- 110.9)

Leptin (ng/ml) 39.1 ± 22.6 (7.8 -- 83.3) 42.1 ± 18.1 25.2 ± 18.4[a](#) (5.5 -- 59.8) 29.7 ± 14.9 [a](#) (11.9 -- 53.7)
15.1 -- 81.2



## Glucose (mg/dL) 95.0 ± 6.1 (86.1 --109.7) 99.3 ± 7.5 (88.3 -- 100.5) 95.1 ± 7.5 (87.2 -- 118.7) 91.2 ± 4.3 (85.3 -- 100.6)

Data are presented as means ± s.d. Values in parentheses are ranges.

Significantly different from values after 12 weeks diet (\<0.001, paired
t-test)::::


Extracted trial result:
Outcome: weight loss (continuous)
Intervention: 1500 mg calcium
Comparator: 500 mg calcium
Intervention group size: 17
Comparator group size: 17
Notes: assumed group sizes were half and half of 34, values for low and high calcium groups have multiple seperated groups within them