Camilla Hoppe

High intakes of skimmed milk, but not meat, increase serum IGF-I and IGFBP-3 in eight-year-old boys

Objective: To examine whether a high protein intake (PI) from either milk or meat, at a level often seen in late infancy, could increase s-IGF-I and s-IGF-I/s-IGFBP-3 in healthy, prepubertal children. IGF-I levels are positively associated with growth velocity in children and some studies suggest that a high animal PI can stimulate growth. During protein deprivation IGF-I decrease, but it is unknown whether a high PI can increase s-IGF-I in well-nourished children.Design: In all, 24 8-y-old boys were asked to take either 1.5u2009l of skimmed milk (n=12) or the same amount of protein as 250u2009g low fat meat (n=12) daily for 7 days. The remaining diet they could choose freely. At baseline and after 7 days, anthropometrical variables were measured, diet was registered (3-day weighed records), and s-IGF-I and s-IGFBP-3 (RIA) were determined after fast.Results: PI increased by 61% in the milk group to 4.0u2009g/kg/day (P<0.0001) and by 54% in the meat group to 3.8u2009g/kg/day (P=0.001). The high milk intake increased s-IGF-I by 19% (P=0.001) and s-IGF-I/s-IGFBP-3 by 13% (P<0.0001). There were no increases in the meat group.Conclusions: High intake of milk and not meat, increased concentrations of s-IGF-I and s-IGF-I/s-IGFBP-3 significantly. Compounds in milk and not a high PI as such seem to stimulate IGF-I. This might explain the positive effect of milk intake on growth seen in some studies.

High intakes of milk, but not meat, increase s-insulin and insulin resistance in 8-year-old boys

Objective:Our objective was to examine if a high animal protein intake from milk or meat increased s-insulin and insulin resistance in healthy, prepubertal children. A high animal protein intake results in higher serum branched chain amino acids (BCAA; leucine, isoleucine and valine) concentrations, which are suggested to stimulate insulin secretion. Furthermore, milk possesses some postprandial insulinotrophic effect that is not related to its carbohydrate content.Design:A total of 24 8-y-old boys were asked to take 53 g protein as milk or meat daily. At baseline and after 7 days, diet was registered, and insulin, glucose, and amino acids were determined. Insulin resistance and beta cell function were calculated with the homeostasis model assessment.Results:Protein intake increased by 61 and 54% in the milk- and meat-group, respectively. In the milk-group, fasting s-insulin concentrations doubled, which caused the insulin resistance to increase similarly. In the meat-group, there was no increase in insulin and insulin resistance. As the BCAAs increased similarly in both groups, stimulation of insulin secretion through BCAAs is not supported.Conclusions:Our results indicate that a short-term high milk, but not meat, intake increased insulin secretion and resistance. The long-term consequences of this are unknown. The effect of high protein intakes from different sources on glucose–insulin metabolism needs further studying.

Early programming of the IGF-I axis: negative association between IGF-I in infancy and late adolescence in a 17-year longitudinal follow-up study of healthy subjects.

BACKGROUNDnIGF-I is a major regulator of growth, influenced primarily by diet in infancy and primarily by GH in childhood. Breastfed infants have lower IGF-I levels compared to formula fed and tend to be shorter. The higher protein content of infant formula has a stimulatory effect on IGF-I production. Conversely, studies suggest that later in childhood, those breastfed are taller and have higher IGF-I levels. Therefore, it has been suggested that the IGF-I axis may be programmed by diet during infancy. The association between IGF-I in infancy and later life is not known.nnnOBJECTIVEnTo examine the association between IGF-I in infancy and adolescence.nnnDESIGNnInfants (109) from the observational Copenhagen cohort study.nnnMETHODSnSerum-IGF-I was measured during infancy (2, 6, and 9 months) and at follow-up at 17 years. Associations were examined by correlation tests and linear regression controlling for gender, breastfeeding, and other covariates. Likelihood ratio test based on residual log likelihood was applied for analysis including all measurements during infancy.nnnRESULTSnThere was an inverse association between IGF-I at 9 months and 17 years (r=-0.39, P=0.014, and n=40). A 1 ng/ml higher IGF-I concentration at 9 months corresponded to 0.95 ng/ml lower IGF-I concentration at 17 years. IGF-I levels at 2 and 6 months were not significantly associated with IGF-I at 17 years, but the estimated directions were negative. These associations were not changed when adjusted for breastfeeding and other covariates except IGF-I at 2 months which was significantly negatively associated with IGF-I at 17 years (P=0.030) corresponding to a 0.96 ng/ml lower IGF-I concentration at 17 years per ng/ml IGF-I at 2 months. Inclusion of all measurements during infancy showed a negative association with 17-year values (r=-0.26, P=0.043, and n=109).nnnCONCLUSIONnThe results support the hypothesis that the IGF-I axis can be programmed early in life.

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±4u2009kg/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.

Dietary protein intake and bone mineral content in adolescents-The Copenhagen Cohort Study.

SummaryData indicate that various protein sources may exhibit a differential effect on bone metabolism. We investigated associations of milk and meat protein intake with bone mineral content (BMC) in adolescents. Milk, but not meat, protein intake was positively associated with size-adjusted BMC. Milk-derived protein may be beneficial for bone mineralization.IntroductionMilk and meat protein intake has been reported to exhibit a differential effect on serum insulin-like growth factor-I (IGF-I). IGF-I plays a key role in bone metabolism. Therefore, we investigated associations of different protein sources with BMC and bone area (BA) in adolescents.MethodsThis was a cross-sectional study of 17-year-old girls (nu2009=u200963) and boys (nu2009=u200946) participating in the second follow-up of The Copenhagen Cohort Study. We measured dietary intake (7-day food record), BMC and BA (dual-energy X-ray absorptiometry), serum markers for bone turnover and serum IGF-I (immunoassays).ResultsThe mean total protein intake (∼1.2xa0g/kg) was modestly higher than that recommended. Total and milk (∼0.3xa0g/kg) protein intake, but not meat protein intake (∼0.4xa0g/kg), was positively associated with size-adjusted BMC (Pu2009≤u20090.05). The positive association between milk protein intake and size-adjusted BMC remained significant after correction for energy, calcium, and physical activity (Pu2009≤u20090.01) and did not seem to be mediated via current serum IGF-I. None of the analyzed protein sources was significantly associated with size-adjusted BA.ConclusionsOur results suggest that some components of milk protein may promote bone mineralization. Further studies are needed to elucidate this phenomenon.

Nuclear magnetic resonance–based metabonomics reveals strong sex effect on plasma metabolism in 17-year–old Scandinavians and correlation to retrospective infant plasma parameters

Nuclear magnetic resonance (NMR)-based metabonomics was carried out on plasma samples from a total of seventy-five 17-year-old Danes to investigate the impact of key parameters such as sex, height, weight, and body mass index on the plasma metabolite profile in a normal, healthy population. Principal component analysis identified sex to have a large impact on the NMR plasma metabolome, whereas no apparent effects of height, weight, and body mass index were found. Partial least square regression discriminant analysis and quantification of relative metabolite concentrations by integration of NMR signals revealed that the sex effect included differences in plasma lipoproteins (mainly high-density lipoprotein), glucose, choline, and amino acid content. Accordingly, the present study suggests a higher lipid synthesis in young women than young men and a higher protein turnover in young men compared with women. Data on plasma content of triglyceride, lipoprotein fractions, and cholesterol at an age of 9 months were available for selected individuals (n = 40); and partial least square regressions revealed correlations between these infant parameters and the NMR plasma metabolome at an age of 17 years. In conclusion, the present study demonstrates the feasibility of NMR-based metabonomics for obtaining a deeper insight into interindividual differences in metabolism and for exploring relationships between parameters measured early in life and metabolic status at a later stage.

High intake of milk, but not meat, decreases bone turnover in prepubertal boys after 7 days

Objective:To compare the short-term effect of a high milk and a high meat intake, identical in protein amount, on bone turnover during prepuberty.Setting:A University Department.Design and Subjects:From 28, randomly recruited, 8-year-old boys, first 14 were assigned to the milk group and next 14 to the meat group. In each group, 12 boys finished the dietary intervention.Intervention:Milk (1.5u2009l/day) and meat (250u2009g/d), both containing ∼53u2009g of protein, were given together with the habitual diet for 7 days. At baseline and day−7, serum osteocalcin (s-OC), bone-specific alkaline phosphatase (s-BAP) and C-terminal telopeptides of type I collagen (s-CTX) were measured (immunoassay) and dietary intake was estimated (a 3-day weighted food record).Results:Baseline s-OC, s-BAP and s-CTX were not significantly different between the groups. After 7 days, the average protein intake increased in both groups by 47.5u2009g; the milk group had higher (P<0.0001) calcium intake; s-OC and s-CTX decreased (P⩽0.04) in the milk group (−30.9%; −18.7%, respectively) compared with the meat group (+6.4%; −1.0%, respectively) and s-BAP decreased (P=0.06) both in the milk (−3.9%) and the meat group (−7.5%).Conclusions:At the equal protein intake, milk, but not meat, decreased bone turnover in prepubertal boys after 7 days. This effect was probably due to some milk-derived compounds, rather than to the total protein intake. Future studies should elucidate the mechanism(s) of milk-related decline of bone turnover and its relevance for peak bone mass during growth.Sponsorship:University PhD scholarships.

Whole cow's milk: why, what and when?

There are differences between at what age industrialized countries recommend that cows milk can be introduced to infants. Most countries recommend waiting until 12 months of age, but according to recommendations from some countries (e.g. Canada, Sweden and Denmark) cows milk can be introduced from 9 or 10 months. The main reason for delaying introduction is to prevent iron deficiency as cows milk is a poor iron source. In one study mainly milk intake above 500 ml/day caused iron deficiency. Cows milk has a very low content of linoleic acid (LA), but a more favorable LA/alpha-linolenic ratio, which is likely to be the reason why red blood cell docosahexaenoic acid (DHA) levels seem to be more favorable in infants drinking cows milk compared to infants drinking infant formula that is not supplemented with DHA. It has been suggested that cows milk intake can affect the later risk of obesity, blood pressure and linear growth, but the evidence is not convincing. There are also considerable differences in recommendations on at what age cows milk with reduced fat intake can be introduced. The main consideration is that low-fat milk might limit energy intake and thereby growth, but the potential effects on development of early obesity should also be considered. Recommendations about the age for introduction of cows milk should take into consideration traditions and feeding patterns in the population, especially the intake of iron and long-chain polyunsaturated fatty acids and should also give recommendations on the volume of milk.

Short-term effects of replacing milk with cola beverages on insulin-like growth factor-I and insulin–glucose metabolism: a 10 d interventional study in young men

In the Western world, a trend towards increased consumption of carbonated soft drinks combined with a decreasing intake of milk is observed. This may affect circulating insulin-like growth factor I (IGF-I) and fasting insulin, as seen in pre-pubertal children. The present study was designed to reflect the trend of replacing milk with carbonated beverages in young men and to study the effects of this replacement on IGF-I, IGF-binding protein 3 (IGFBP-3), IGF-I:IGFBP-3 and glucose-insulin metabolism. A randomised, controlled crossover intervention study, in which eleven men aged 22-29 years were given a low-Ca diet in two 10 d periods with 10 d washout in between. In one period, they drank 2.5 litres of Coca Cola(R) per day and the other period 2.5 litres of semi-skimmed milk. Serum IGF-I, IGFBP-3 (RIA), insulin (fluoro immunoassay) and glucose (Cobas) were determined at baseline and end point of each intervention period. Insulin resistance and beta-cell function were calculated with the homeostasis model assessment. A decrease in serum IGF-I was observed in the cola period compared with the milk period (P < 0.05). No effects of treatment were observed on IGFBP-3, IGF-I:IGFBP-3, insulin, glucose, insulin resistance or beta-cell function. The present study demonstrates that high intake of cola over a 10 d period decreases total IGF-I compared with a high intake of milk, with no effect on glucose-insulin metabolism in adult men. It is unknown whether this is a transient phenomenon or whether it has long-term consequences.

Reporting accuracy of packed lunch consumption among Danish 11-year-olds differ by gender.

Background Packed lunch is the dominant lunch format in many countries including Denmark. School lunch is consumed unsupervised, and self-reported recalls are appropriate in the school setting. However, little is known about the accuracy of recalls in relation to packed lunch. Objective To assess the qualitative recall accuracy of self-reported consumption of packed lunch among Danish 11-year-old children in relation to gender and dietary assessment method. Design A cross-sectional dietary recall study of packed lunch consumption. Digital images (DIs) served as an objective reference method to determine food items consumed. Recalls were collected with a lunch recall questionnaire (LRQ) comprising an open-ended recall (OE-Q) and a pre-coded food group prompted recall (PC-Q). Individual interviews (INTs) were conducted successively. The number of food items was identified and accuracy was calculated as match rates (% identified by DIs and reported correctly) and intrusion rates (% not identified by DIs but reported) were determined. Setting and subjects Three Danish public schools from Copenhagen. A total of 114 Danish 11-year-old children, mean (SE) age=11.1 (0.03), and body mass index=18.2 (0.26). Results The reference (DIs) showed that girls consumed a higher number of food items than boys [mean (SE) 5.4 (0.25) vs. 4.6 (0.29) items (p=0.05)]. The number of food items recalled differed between genders with OE-Q recalls (p=0.005) only. Girls’ interview recalls were more accurate than boys’ with higher match rates (p=0.04) and lower intrusion rates (p=0.05). Match rates ranged from 67–90% and intrusion rates ranged from 13–39% with little differences between girls and boys using the OE-Q and PC-Q methods. Conclusion Dietary recall validation studies should not only consider match rates as an account of accuracy. Intrusions contribute to over-reporting in non-validation studies, and future studies should address recall accuracy and inaccuracies in relation to gender and recall method.