Janne K. Lorenzen

Effect of dairy calcium on fecal fat excretion: a randomized crossover trial

Background:Evidence suggests that dietary calcium intake may be inversely related to body weight. One explanatory mechanism is that dietary calcium increases fecal fat excretion, due to either calcium soap formation and/or binding of bile acids (BAs) in the intestine.Objective:To examine the effect of calcium from low-fat dairy products on fecal fat excretion.Design:A randomized crossover study with 11 subjects, comparing two 7-d diets: one high in calcium from low-fat dairy products (high-Ca; 2300 mg Ca per d) and one low in calcium (low-Ca; 700 mg Ca per d).Measurements:All feces were collected during the last 5 days of each diet period and analyzed for fat, energy and calcium content and fatty acid (FA) and BA composition.Results:Dairy calcium significantly increased the total fecal fat excretion from 5.4±0.5 g d−1 on the low-Ca diet to 11.5±1.4 g d−1 on the high-Ca diet (P<0.001). The fecal energy excretion increased almost correspondingly. Saturated, monounsaturated and polyunsaturated FAs were all excreted in larger amounts on the high-Ca diet (P<0.001 for all), with the effect of calcium being greater for monounsaturated than for saturated FAs. The fecal excretion of BAs was unaffected of calcium intakes.Conclusions:Increasing the intake of calcium from low-fat dairy products by 1600 mg d−1 for 7 days doubled total fecal fat excretion, but did not affect the excretion of BAs. The results may partially explain why a high-calcium diet can produce weight loss.

Effect of dairy calcium from cheese and milk on fecal fat excretion, blood lipids, and appetite in young men

BACKGROUND Calcium from different dairy sources might affect blood lipids and fecal fat excretion differently because of differences in the food matrix and nutritional composition. OBJECTIVE We investigated whether milk- and cheese-based diets with similar calcium contents affect a saturated fatty acid-induced increase in blood lipids differently. DESIGN Fifteen healthy, young men participated in a randomized 3 × 2-wk crossover study in which the following 3 isocaloric diets that were similar in fat contents and compositions were compared: control diet [nondairy diet (~500 mg Ca/d)], milk diet [semiskimmed milk-based diet (1700 mg Ca/d)], and cheese diet [semihard cow-cheese-based diet (1700 mg Ca/d)]. Blood was drawn before and after each period, and feces were collected for 5 d during each period. RESULTS Saturated fatty acid-induced increases in total and low-density lipoprotein (LDL) cholesterol were lower with the milk diet (mean ± SD: 0.57 ± 0.13 and 0.53 ± 0.11 mmol/L, respectively) (P < 0.01) and cheese diet (0.41 ± 0.15 and 0.47 ± 0.12 mmol/L, respectively) (P < 0.05) than with the control diet (0.89 ± 0.12 and 0.84 ± 0.11 mmol/L, respectively). Fecal fat excretion increased more with the consumption of both the milk (5.2 ± 0.4 g/d) and cheese (5.7 ± 0.4 g/d) diets than with the control diet (3.9 ± 0.3 g/d) (P < 0.001). Changes in blood pressure, high-density lipoprotein cholesterol, triglycerides, and lipid ratios did not differ. CONCLUSIONS Compared with the control diet, milk- and cheese-based diets attenuated saturated fatty acid-induced increases in total and LDL cholesterol and resulted in increased fecal fat excretion; however, effects of milk and cheese did not differ. Because the diets contained similar amounts of saturated fat, similar increases in total and LDL cholesterol could be expected; however, both milk and cheese attenuated these responses, which seem to be explained by their calcium contents. This trial was registered at clinicaltrials.gov as NCT01317251.

The effect of milk proteins on appetite regulation and diet-induced thermogenesis

Background/objectives:There is increasing evidence to support that a high-protein diet may promote weight loss and prevent weight (re)gain better than a low-protein diet, and that the effect is due to higher diet-induced thermogenesis (DIT) and increased satiety. However, data on the effect of different types of protein are limited. In the present study we compare the effect of whey, casein and milk on DIT and satiety.Subjects/methods:Seventeen slightly overweight (29±4 kg/m2) male subjects completed the study. The study had a randomized, crossover design, where the effect on 4 h postprandial energy expenditure (EE), substrate oxidation and subjective appetite sensation of three isocaloric test meals containing either a whey drink, a casein drink or skim milk was examined. Energy intake (EI) at a subsequent ad libitum lunch was also measured.Results:There was no significant effect on subjective appetite sensation, but EI at lunch was lower after the milk test meal than after the casein (9%; P=0.0260) and the whey (9%; P=0.0258) test meals. Postprandial lipid oxidation was significantly higher after the casein test meal compared with the whey test meal (P=0.0147) when adjusted for baseline values. There was no significant difference in effect on EE, protein oxidation or carbohydrate oxidation.Conclusions:Milk reduced subsequent EI more than isocaloric drinks containing only whey or casein. A small but significant increase in lipid oxidation was seen after casein compared with whey.

Metabolomics Investigation To Shed Light on Cheese as a Possible Piece in the French Paradox Puzzle

An NMR-based metabolomics approach was used to investigate the differentiation between subjects consuming cheese or milk and to elucidate the potential link to an effect on blood cholesterol level. Fifteen healthy young men participated in a full crossover study during which they consumed three isocaloric diets with similar fat contents that were either (i) high in milk, (ii) high in cheese with equal amounts of dairy calcium, or (iii) a control diet for 14 days. Urine and feces samples were collected and analyzed by NMR-based metabolomics. Cheese and milk consumption decreased urinary choline and TMAO levels and increased fecal excretion of acetate, propionate, and lipid. Compared with milk intake, cheese consumption significantly reduced urinary citrate, creatine, and creatinine levels and significantly increased the microbiota-related metabolites butyrate, hippurate, and malonate. Correlation analyses indicated that microbial and lipid metabolism could be involved in the dairy-induced effects on blood cholesterol level.

Can bioactive foods affect obesity

Many dietary factors or substances exert effects on the three components of energy balance, and one strategy for tackling weight gain could be to use the inherent properties of these substances. Here, we will review the evidence regarding nutritional factors with a potential impact on energy balance, such as wholegrain foods, dietary fiber and protein content, calcium, and certain spices. There is ample evidence to suggest that dietary protein, wholegrain, and fiber promote satiety and either reduce energy absorption or stimulate energy expenditure. Dietary calcium reduces fat absorption, and a sufficient intake may also prevent excessive hunger during weight loss diets. Chili and mustard have beneficial effects on energy balance, although the quantitative importance of this may be modest. Manipulation of diet composition with an aim to prevent weight gain and weight regain is a promising avenue of research.

Dairy beverages and energy balance

High dairy intakes have been associated with lower rates of obesity in observational studies, but mechanisms to explain the association are lacking. A high intake of dairy protein reduces spontaneous food intake and may be one important mechanism, but more specific effects of dairy calcium seem to exist. We have found that high versus low calcium intakes from dairy products had no effect on 24-h energy expenditure or substrate oxidation rates, but fecal fat excretion increased approximately 2.5-fold on the high-calcium diets. In a meta-analysis of intervention studies we found that increasing dairy calcium intake by 1200mg/day resulted in increased fecal fat excretion by 5.2 (1.6-8.8) g/day. Newer research shows that humans possess taste receptors for calcium in the gastrointestinal tract and that signaling may be linked to appetite regulation. A new line of evidence suggests that an inadequate calcium intake during an energy restricted weight loss program may trigger hunger and impair compliance to the diet. These mechanisms may be part of the explanation for the protective effects of dairy products with regard to obesity and metabolic syndrome.

Milk minerals modify the effect of fat intake on serum lipid profile: results from an animal and a human short-term study

Despite a high content of saturated fat, evidence from observational studies indicates that the consumption of dairy products may have a neutral effect or may be inversely associated with the risk of CVD. We aimed to examine whether milk minerals modify the effect of saturated fat on serum lipid profile. We present data from two studies. Study I had a randomised, blinded, parallel design (n 24 pigs) with a 10 d adaptation period during which a high-fat diet was fed to the pigs and a 14 d intervention period during which the same diet either enriched with milk minerals (MM group) or placebo (control group) was fed to the pigs. Study II had a randomised cross-over design (n 9 men) where the subjects were fed either a high-fat diet enriched with milk minerals (MM period) or a regular diet (control period). In both the studies, blood variables were measured before and after the intervention and faecal and urine samples were collected at the end of the dietary periods. The increase in plasma total cholesterol and LDL-cholesterol concentrations but not in HDL-cholesterol concentration was markedly lowered by milk minerals in both the studies. In the animal study, baseline adjusted total cholesterol and LDL-cholesterol concentrations in the MM group were 11% (P = 0.004) and 13% (P = 0.03) lower compared with those in the control group after the intervention. Similarly in the human study, baseline adjusted total cholesterol and LDL-cholesterol concentrations were 6% (P = 0.002) and 9% (P = 0.03) lower after the MM period compared with those in the control period. HDL-cholesterol concentration was not lowered by milk minerals. These short-term studies indicate that the addition of milk minerals to a high-fat diet to some extent attenuates the increase in total cholesterol and LDL-cholesterol concentrations, without affecting HDL-cholesterol concentration.

Serum Levels of Human MIC-1/GDF15 Vary in a Diurnal Pattern, Do Not Display a Profile Suggestive of a Satiety Factor and Are Related to BMI

The TGF-b superfamily cytokine MIC-1/GDF15 circulates in the blood of healthy humans. Its levels rise substantially in cancer and other diseases and this may sometimes lead to development of an anorexia/cachexia syndrome. This is mediated by a direct action of MIC-1/GDF15 on feeding centres in the hypothalamus and brainstem. More recent studies in germline gene deleted mice also suggest that this cytokine may play a role in physiological regulation of energy homeostasis. To further characterize the role of MIC-1/GDF15 in physiological regulation of energy homeostasis in man, we have examined diurnal and food associated variation in serum levels and whether variation in circulating levels relate to BMI in human monozygotic twin pairs. We found that the within twin pair differences in serum MIC-1/GDF15 levels were significantly correlated with within twin pair differences in BMI, suggesting a role for MIC-1/GDF15 in the regulation of energy balance in man. MIC-1/GDF15 serum levels altered slightly in response to a meal, but comparison with variation its serum levels over a 24hour period suggested that these changes are likely to be due to bimodal diurnal variation which can alter serum MIC-1/GDF15 levels by about plus or minus 10% from the mesor. The lack of a rapid and substantial postprandial increase in MIC-1/GDF15 serum levels suggests that MIC1/GDF15 is unlikely to act as a satiety factor. Taken together, our findings suggest that MIC-1/GDF15 may be a physiological regulator of energy homeostasis in man, most probably due to actions on long-term regulation of energy homeostasis.

Associations between dairy protein intake and body weight and risk markers of diabetes and CVD during weight maintenance

Dairy products have previously been reported to be associated with beneficial effects on body weight and metabolic risk markers. Moreover, primary data from the Diet, Obesity and Genes (DiOGenes) study indicate a weight-maintaining effect of a high-protein-low-glycaemic index diet. The objective of the present study was to examine putative associations between consumption of dairy proteins and changes in body weight and metabolic risk markers after weight loss in obese and overweight adults. Results were based on secondary analyses of data obtained from overweight and obese adults who completed the DiOGenes study. The study consisted of an 8-week weight-loss phase and a 6-month weight-maintenance (WM) phase, where the subjects were given five different diets varying in protein content and glycaemic index. In the present study, data obtained from all the subjects were pooled. Dairy protein intake was estimated from 3 d dietary records at two time points (week 4 and week 26) during the WM phase. Body weight and metabolic risk markers were determined at baseline (week -9 to -11) and before and at the end of the WM phase (week 0 and week 26). Overall, no significant associations were found between consumption of dairy proteins and changes in body weight and metabolic risk markers. However, dairy protein intake tended to be negatively associated with body weight gain (P=0·08; β=-0·17), but this was not persistent when controlled for total protein intake, which indicates that dairy protein adds no additional effect to the effect of total protein. Therefore, the present study does not report that dairy proteins are more favourable than other proteins for body weight regulation.

Protein supplements after weight loss do not improve weight maintenance compared with recommended dietary protein intake despite beneficial effects on appetite sensation and energy expenditure: a randomized, controlled, double-blinded trial

Background: High-protein diets increase weight loss (WL) during energy restriction; therefore, it has been suggested that additional protein intake may improve weight maintenance (WM) after WL.Objective: We investigated the effect of protein supplements from either whey with or without calcium or soy on WM success after WL compared with that of a control.Design: In a randomized, controlled, double-blinded trial, 220 participants aged 18-60 y with body mass index (in kg/m2) from 27.6 to 40.4 were included. The study was initiated with an 8-wk WL period followed by a 24-wk WM period. During WM, participants consumed the following isocaloric supplements (45-48 g/d): whey and calcium (whey+), whey, soy, or maltodextrin (control). Data were collected at baseline, before WM, and after WM (weeks 0, 8, and 32, respectively) and included body composition, blood biochemistry, and blood pressure. Meal tests were performed to investigate diet-induced-thermogenesis (DIT) and appetite sensation. Compliance was tested by 24-h urinary nitrogen excretion.Results: A total of 151 participants completed the WM period. The control and 3 protein supplements did not result in different mean ± SD weight regains (whey+: 2.19 ± 4.6 kg; whey: 2.01 ± 4.6 kg; soy: 1.76 ± 4.7 kg; and control: 2.23 ± 3.8 kg; P = 0.96), fat mass regains (whey+: 0.46 ± 4.5 kg; whey: 0.11 ± 4.1 kg; soy: 0.15 ± 4.1 kg; and control: 0.54 ± 3.3 kg; P = 0.96), or improvements in lean body mass (whey+: 1.87 ± 1.7 kg; whey: 1.94 ± 1.3 kg; soy: 1.58 ± 1.4 kg; and control: 1.74 ± 1.4 kg; P = 0.50) during WM. Changes in blood pressure and blood biochemistry were not different between groups. Compared with the control, protein supplementation resulted in higher DIT (∼30 kJ/2.5 h) and resting energy expenditure (243 kJ/d) and an anorexigenic appetite-sensation profile.Conclusion: Protein supplementation does not result in improved WM success, or blood biochemistry after WL compared with the effects of normal dietary protein intake (0.8-1.0 g · kg-1 · d-1). This trial was registered at clinicaltrials.gov as NCT01561131.