Human Milk Oligosaccharides, Important Milk Bioactives for Child Health: A Perspective

Human milk contains all nutritive and bioactive compounds to give infants the best possible start in life. Human milk bioactives cover a broad range of components, including immune cells, antimicrobial proteins, microbes, and human milk oligosaccharides (HMOs). Over the last decade, HMOs have gained special attention as their industrial production has allowed the study of their structure-function relation in reductionist experimental setups. This has shed light on how HMOs steer microbiome and immune system development in early life but also how HMOs affect infant health (e.g., antibiotic use, respiratory tract infections). We are on the verge of a new era where we can examine human milk as a complex biological system. This allows not only study of the mode of action and causality of individual human milk components but also investigation of synergistic effects that might exist between different bioactives. This new wave in human milk research is largely fueled by significant advances in analytical tools in the field of systems biology and network analysis. It will be exciting to explore how human milk composition is affected by different factors, how different human milk compounds work together, and how this influences healthy infant development.

Infant Formula With a Specific Blend of Five Human Milk Oligosaccharides Drives the Gut Microbiota Development and Improves Gut Maturation Markers: A Randomized Controlled Trial

Background

Human milk oligosaccharides (HMOs) have important biological functions for a healthy development in early life.

Objective

This study aimed to investigate gut maturation effects of an infant formula containing five HMOs (2′-fucosyllactose, 2′,3-di-fucosyllactose, lacto-N-tetraose, 3′-sialyllactose, and 6′-sialyllactose).

Methods

In a multicenter study, healthy infants (7–21 days old) were randomly assigned to a standard cow’s milk-based infant formula (control group, CG); the same formula with 1.5 g/L HMOs (test group 1, TG1); or with 2.5 g/L HMOs (test group 2, TG2). A human milk-fed group (HMG) was enrolled as a reference. Fecal samples collected at baseline (n∼150/formula group; HMG n = 60), age 3 (n∼140/formula group; HMG n = 65) and 6 (n∼115/formula group; HMG n = 60) months were analyzed for microbiome (shotgun metagenomics), metabolism, and biomarkers.

Results

At both post-baseline visits, weighted UniFrac analysis indicated different microbiota compositions in the two test groups (TGs) compared to CG (P < 0.01) with coordinates closer to that of HMG. The relative abundance of Bifidobacterium longum subsp. infantis (B. infantis) was higher in TGs vs. CG (P < 0.05; except at 6 months: TG2 vs. CG P = 0.083). Bifidobacterium abundance was higher by ∼45% in TGs vs. CG at 6-month approaching HMG. At both post-baseline visits, toxigenic Clostridioides difficile abundance was 75–85% lower in TGs vs. CG (P < 0.05) and comparable with HMG. Fecal pH was significantly lower in TGs vs. CG, and the overall organic acid profile was different in TGs vs. CG, approaching HMG. At 3 months, TGs (vs. CG) had higher secretory immunoglobulin A (sIgA) and lower alpha-1-antitrypsin (P < 0.05). At 6 months, sIgA in TG2 vs. CG remained higher (P < 0.05), and calprotectin was lower in TG1 (P < 0.05) vs. CG.

Conclusion

Infant formula with a specific blend of five HMOs supports the development of the intestinal immune system and gut barrier function and shifts the gut microbiome closer to that of breastfed infants with higher bifidobacteria, particularly B. infantis, and lower toxigenic Clostridioides difficile.

Clinical Trial Registration

[https://clinicaltrials.gov/ct2/show/], identifier [NCT03722550].

Human Milk Fortifiers for Preterm Infants: Do We Offer the Best Amino Acid Mix?

For preterm and small-for-gestational age infants on enteral nutrition, the best solution is to add human milk fortifier (HMF) to human milk (HM) which is provided by the mother or a milk bank. HMF provides a means to add additional protein, energy, and micronutrients, while maintaining HM as the main source of nutrition. Because of their rapid increase of lean body mass, preterm infants have much higher protein requirements than term infants. Recommendations on protein requirements of preterm infants are available, but protein quality - i.e. the amino acid (AA) profile in HMFs has not been systematically assessed. Present guidelines for enteral nutrition recommend protein intakes around 4 g/kg body weight (BW) for preterm infants <1,500 g, an intake that is not achievable with unfortified HM intakes <200 mL/kg BW/day. It is generally assumed that the AA profile of HM is the best reference for the AA profile of HMF. We calculated advisable intakes of AAs for preterm infants between 400-2,500 g which are based on AA increments of the fetus. Corrections for absorption, inevitable losses, oxidation, and variation of AAs in HM were introduced. Our calculations indicate that extremely low birth weight (ELBW <1,000 g) and very low birth weight (VLBW <1,500 g) infants have substantially higher AA requirements than low birth weight (LBW) infants growing from 1,900 to 2,400 g. In ELBW infants, daily intakes of the different indispensable AAs (IAA) with 4 g of (term) HM protein/kg BW range between 59 and 125% of the respective advisable intakes. Intakes of 7 IAAs and 3 conditionally indispensable AAs (CIAA) are below advisable intakes. On the other hand, with 4 g HM protein per kg BW/day, the IAAs isoleucine and leucine and some dispensable AAs are already supplied in abundance. In VLBW infants, daily intakes of the IAA methionine and 3 CIAAs are still below the advisable intakes. In LBW infants (<2,000 g) receiving 3.5 g HM protein per kg BW daily intakes of 1 IAA and 3 CIAAs would be too low. Preterm infants should receive HMFs which provide adequate amounts of AAs which are needed for their rapid growth and development while avoiding excessive intakes. In particular, very high AA requirements of ELBW infants are a challenge. AA composition of present HMFs for preterm infants should be reconsidered: spiking HMF protein with the AAs which are presently undersupplied or providing targeted AA-based HMF are options to further improve the AA profile in fortifiers.

Effect of milk protein content in Toddler formula on later BMI and obesity risk: protocol of the multicentre randomised controlled Toddler Milk Intervention (ToMI) trial

INTRODUCTION

Reduction of milk protein content in infant formula provided during the first year of life has been shown to reduce early weight gain and obesity later in life. While rapid weight gain during the first 2 years of life is one of the strongest early predictors of obesity, the role of animal protein intake beyond the first year of life is unclear. The aim of this study is to examine the role of milk protein during the second year of life in healthy children on weight gain and obesity risk in preschool age.

METHODS AND ANALYSIS

This randomised, double-blinded study enrolled 1618 children aged 11.5-13.5 months in Spain and Germany into two groups receiving isocaloric toddler milk with differing protein content during the second year of life. The experimental formula contains 1.5 g/100 kcal and the control formula 6.15 g/100 kcal protein and otherwise equal formula composition, except for modified fat content to achieve equal energy density. The primary endpoint is body mass index (BMI)-for-age z-score at the age of 24 months adjusted for BMI at 12 months of age. The children are followed until 6 years of age.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the ethical committees of the LMU University Hospital Munich, Germany (Nr. 555-15) and at Institut d'Investigació Sanitaria Pere Virgili, Reus, Spain (Ref. CEIm IISPV 013/2016). We aim at publishing results in peer-reviewed journals and sharing of results with study participants.

TRIAL REGISTRATION NUMBER

NCT02907502.

Estimated Energy Requirements of Infants and Young Children up to 24 Months of Age

BACKGROUND

Establishing energy requirements in infants and young children is important in developing age-appropriate diet recommendations but most published guidelines for energy requirements have 1 or more limitations related to the data underlying the calculations.

OBJECTIVE

To develop a comprehensive set of daily energy requirements for infants and young children aged 0-24 mo meeting the ideals of worldwide applicability to all healthy children based on the use of the doubly labeled water (DLW) technique to measure total energy expenditure (TEE), the use of recent, international growth charts, and calculation of values across a wide range of body weight.

METHODS

Daily estimated energy requirements (EERs) were calculated in 1-mo increments from 0 to 24 mo for boys, girls, and combined, using as inputs the following: 1) TEE measured using the DLW technique, 2) energy deposition estimates from the Institute of Medicine, and 3) body weight values from the 25th to 75th percentiles from the 2006 WHO growth charts. EERs were combined for age groups 0 to <6, 6-8, 9-11, and 12-24 mo by averaging EERs from individual months. The EER calculations were supported by a systematic literature review and a meta-regression of existing studies.

RESULTS

Energy requirements naturally increase with age and are slightly higher in boys than in girls. The EERs derived in this study are similar to those in other recent international efforts.

CONCLUSIONS

This updated set of EERs for infants and young children expand and improve upon the methodology used to establish previous published guidelines. These estimates have multiple potential uses including planning age-appropriate menus for the complementary feeding period, the development of foods that are more precisely targeted to the needs of infants and children at particular ages, and establishing macronutrient requirements within specific age groups based on a percentage of energy, such as dietary fat.

Real-World Effectiveness of a New Growing Up Milk on Digestive Comfort and Social-Emotional Outcomes Among Healthy Toddlers in China

Objectives

Existing clinical evidence indicates infant formulas containing bovine milk-derived oligosaccharides (MOS) promote soft stools and gut health among young infants. This prospective single-arm study aimed to assess effectiveness of a new growing-up milk (GUM) containing MOS and milk fat (naturally contains sn-2 palmitate) on digestive and social-emotional outcomes among healthy toddlers.

Methods

Toddlers age 12–36 months were enrolled from an urban area in China to receive the GUM for 28 days. Overall digestive comfort (primary outcome) was assessed by the Gut Comfort Composite Score (GCCS; range 10–60 with increasing scores for higher GI burden) from the 10-item Toddler Gut Comfort Questionnaire (Meng 2019). Other parent-reported culturally relevant outcomes included heatiness based on individual symptoms via Child Heatiness Questionnaire (Sheng 2020; total score range 0–10), and social-emotional outcomes via 3-day mood diary and Children's Playfulness Scale (Li 1995; range 0–69).

Results

A total of 98 toddlers were enrolled and completed the study. While overall GI burden was low at baseline (mean ± SD GCCS: 15.7 ± 4.7; range 10–32), GCCS at post-baseline visits was further reduced (14.7 ± 4.7 at D7, p = 0.02; 13.5 ± 4.0 at D14, p &lt; 0.001; 13.3 ± 3.6 at D28, p &lt; 0.001). Parental report for child heatiness was reduced over study period (0.5 ± 1.2 at D28 vs. 1.0 ± 1.5 [range 0–7] at baseline, p = 0.002). Percentage of toddlers with heatiness (composite score &gt; 0) was 40% at baseline and reduced to 26% by D28 (p = 0.011). Parents reported that their toddlers’ playful behaviors became more important to them by D28 from baseline (median [IQR]: 62 [13] vs. 58 [11.5], p = 0.002). Over 94% of parents reported their toddlers exhibited happy moods at each post-baseline visit, although not statistically different from baseline. Furthermore, lower gut comfort score was associated with more playful behaviors (p &lt; 0.001) and happier mood during daytime (p &lt; 0.001). Over 95% of parents reported their toddlers liked the taste of the GUM and felt happy when drinking it, while 98% of toddlers indicated they liked to drink the GUM.

Conclusions

Consumption of a new GUM with MOS and milk fat is associated with improved gut comfort, increased importance of playfulness and reduced heatiness. Parents also reported happy toddler moods and high satisfaction.

Funding Sources

Sponsored by Wyeth Nutrition.

Iron bioavailability from bouillon fortified with a novel ferric phytate compound: a stable iron isotope study in healthy women (part II)

Bouillon cubes are widely consumed and when fortified with iron could contribute in preventing iron deficiency. We report the development (part I) and evaluation (current part II) of a novel ferric phytate compound to be used as iron fortificant in condiments such as bouillon. Ferric pyrophosphate (FePP), is the compound of choice due to its high stability in foods, but has a modest absorption in humans. Our objective was to assess iron bioavailability from a novel iron fortificant consisting of ferric iron complexed with phytic acid and hydrolyzed corn protein (Fe-PA-HCP), used in bouillon with and without an inhibitory food matrix. In a randomised single blind, cross-over study, we measured iron absorption in healthy adult women (n = 22). In vitro iron bioaccessibility was assessed using a Caco-2 cell model. Iron absorption from Fe-PA-HCP was 1.5% and 4.1% in bouillon with and without inhibitory matrix, respectively. Relative iron bioavailability to FeSO4 was 2.4 times higher than from FePP in bouillon (17% vs 7%) and 5.2 times higher when consumed with the inhibitory meal (41% vs 8%). Similar results were found in vitro. Fe-PA-HCP has a higher relative bioavailability versus FePP, especially when bouillon is served with an inhibitory food matrix.

The bioavailability of iron picolinate is comparable to iron sulfate when fortified into a complementary fruit yogurt: a stable iron isotope study in young women

Purpose

A technological gap exists for the iron (Fe) fortification of difficult-to-fortify products, such as wet and acid food products containing polyphenols, with stable and bioavailable Fe. Fe picolinate, a novel food ingredient, was found to be stable over time in this type of matrix. The objective of this study was to measure the Fe bioavailability of Fe picolinate in a complementary fruit yogurt.

Methods

The bioavailability of Fe picolinate was determined using stable iron isotopes in a double blind, randomized cross-over design in non-anemic Swiss women (n = 19; 25.1 ± 4.6 years). Fractional Fe absorption was measured from Fe picolinate (2.5 mg ⁵⁷Fe per serving in two servings given morning and afternoon) and from Fe sulfate (2.5 mg ⁵⁴Fe per serving in two servings given morning and afternoon) in a fortified dairy complementary food (i.e. yogurt containing fruits). Fe absorption was determined based on erythrocyte incorporation of isotopic labels 14 days after consumption of the last test meal.

Results

Geometric mean (95% CI) fractional iron absorption from Fe picolinate and Fe sulfate were not significantly different: 5.2% (3.8–7.2%) and 5.3% (3.8–7.3%) (N.S.), respectively. Relative bioavailability of Fe picolinate versus Fe sulfate was 0.99 (0.85–1.15).

Conclusion

Therefore, Fe picolinate is a promising compound for the fortification of difficult-to-fortify foods, to help meet Fe requirements of infants, young children and women of childbearing age.

Nutrient pattern analysis in critically ill patients using Omics technology (NAChO) - Study protocol for a prospective observational study

INTRODUCTION

Intensive care unit-acquired weakness (ICU-AW) is often observed in critically ill patients with prolonged intensive care unit (ICU) stay. We hypothesized that evolving metabolic abnormalities during prolonged ICU stay are reflected by changing nutrient patterns in blood, urine and skeletal muscle, and that these patterns differ in patients with/without ICU-AW and between patients with/without sepsis.

METHODS

In a prospective single-center observational trial, we aim to recruit 100 critically ill patients (ICU length of stay ≥ 5 days) with severe sepsis/septic shock ("sepsis group", n = 50) or severe head trauma/intracerebral hemorrhage ("CNS group", n = 50). Patients will be sub-grouped for presence or absence of ICU-AW as determined by the Medical Research Council sum score. Blood and urine samples will be collected and subjected to comprehensive nutrient analysis at different time points by targeted quantitative mass spectrometric methods. In addition, changes in muscular tissue (biopsy, when available), muscular architecture (ultrasound), electrophysiology, body composition analyses (bioimpedance, cerebral magnetic resonance imaging), along with clinical status will be assessed. Patients will be followed-up for 180 and 360 days including assessment of quality of life.

DISCUSSION

Key objective of this trial is to assess changes in nutrient pattern in blood and urine over time in critically ill patients with/without ICU-AW by using quantitative nutrient analysis techniques. Peer-reviewed published NAChO data will allow for a better understanding of metabolic changes in critically ill patients on standard liquid enteral nutrition and will likely open up new avenues for future therapeutic and nutritional interventions.

Timing and pattern of postexercise protein ingestion affects whole-body protein balance in healthy children: a randomized trial

The dose and timing of postexercise protein ingestion can influence whole-body protein balance (WBPB) in adults, although comparable data from children are scarce. This study investigated how protein intake (both amount and distribution) postexercise can affect WBPB in physically active children. Thirty-five children (26 males; 9-13 years old) underwent a 5-day adaptation diet, maintaining a protein intake of 0.95 g·kg^-1·day^-1. Participants consumed [¹⁵N]glycine (2 mg·kg^-1) before performing 3 × 20 min of variable-intensity cycling, and whole-body protein kinetics were assessed over 6 and 24 h of recovery. Fifteen grams of protein was distributed across 2 isoenergetic carbohydrate-containing beverages (15 and 240 min postexercise) containing reciprocal amounts of protein (i.e., 0 + 15 g, 5 + 10 g, 10 + 5 g, and 15 + 0 g for Groups A-D, respectively). Over the 6 h that included the exercise bout and consumption of the first beverage at 15 min postexercise, WBPB (i.e., synthesis - breakdown) demonstrated a linear increase of 0.647 g·kg^-1·day^-1 per 1 g protein intake (P < 0.001). Over 24 h, robust regression revealed that WBPB was best modeled by a parabola (P < 0.05), suggesting that a maximum in WBPB was achieved between groups B and C. In conclusion, despite a dose response early in recovery, a periodized protein intake with multiple smaller doses after physical activity may be more beneficial than a single bolus dose in promoting daily WBPB in healthy active children.

Monoacylglycerol-enriched oil increases EPA/DHA delivery to circulatory system in humans with induced lipid malabsorption conditions

It was hypothesized that under induced lipid malabsorption/maldigestion conditions, an enriched sn-1(3)-monoacylglycerol (MAG) oil may be a better carrier for n-3 long-chain PUFAs (LC-PUFAs) compared with triacylglycerol (TAG) from fish oil. This monocentric double blinded clinical trial examined the accretion of EPA (500 mg/day) and DHA (300 mg/day) when consumed as TAG or MAG, into the erythrocytes, plasma, and chylomicrons of 45 obese (BMI ≥30 kg/m² and ≤40 kg/m²) volunteers who were and were not administered Orlistat, an inhibitor of pancreatic lipases. Intake of MAG-enriched oil resulted in higher accretion of LC-PUFAs than with TAG, the concentrations of EPA and DHA in erythrocytes being, respectively, 72 and 24% higher at 21 days (P < 0.001). In addition, MAG increased the plasma concentration of EPA by 56% (P < 0.001) as compared with TAG. In chylomicrons, MAG intake yielded higher levels of EPA with the area under the curve (0-10 h) of EPA being 55% greater (P = 0.012). In conclusion, in obese human subjects with Orlistat-induced lipid maldigestion/malabsorption conditions, LC-PUFA MAG oil increased LC-PUFA levels in erythrocytes, plasma, and chylomicrons to a greater extent than TAG. These results indicate that MAG oil might require minimal enzymatic digestion prior to intestinal uptake and transfer across the epithelial barrier.

Growth of infants consuming whey-predominant term infant formulas with a protein content of 1.8 g/100 kcal: a multicenter pooled analysis of individual participant data

BACKGROUND

High protein intake during infancy may contribute to obesity later in life in infants who are not exclusively breastfed. Lowering the protein content of infant formula so it is closer to that of mature breast milk may reduce long-term risk of overweight or obesity in formula-fed infants.

OBJECTIVE

We assessed the effects of whey-predominant formulas with a protein content of 1.8 g/100 kcal (lower than that in most current formulas and closer to breast milk) on infant growth by comparing against WHO growth standards and breastfed infants.

DESIGN

A multicenter pooled analysis was conducted with the use of individual participant data (n = 1882) from 11 randomized controlled trials of healthy term infants. Mixed-effects models that used ANCOVA were generated to estimate weight-for-age z score (WAZ), as well as length-for-age, BMI-for-age, and head circumference-for-age z scores at age 4 mo in infants fed a lower-protein infant formula (LPF) or a lower-protein infant formula with additional active ingredients (probiotics, prebiotics, or both) (LPFA) and breastfed infants. Estimates, including 95% CIs, were compared with a ±0.5 SD of WHO growth standards, a benchmark for clinically significant differences.

RESULTS

The 95% CIs for pooled estimates of WAZ were within ±0.5 SD of WHO growth standards for the LPF [0.07 (-0.16, 0.29)] and LPFA [0.22 (0.01, 0.43)] groups. WAZ was higher in the LPF (P < 0.001) and LPFA (P = 0.003) groups than in the breastfed infants, likely because breastfed infants had a relatively low WAZ [-0.23 (-0.51, 0.05)] compared with WHO growth standards. The 95% CIs for all other z scores in the LPF and LPFA groups were within ±0.5 SD of WHO growth standards, except for head circumference, for which the upper limit of the 95% CI slightly exceeded 0.5 SD. No difference was observed in any z scores between the LPF and LPFA groups.

CONCLUSION

Whey-predominant infant formula with a lower protein content that more closely resembles that of breast milk supports healthy growth comparable to the WHO growth standards and close to breastfed infants.

Metabolic Programming: Effects of Early Nutrition on Growth, Metabolism and Body Composition

High protein requirements of premature infants during the first weeks of postnatal life are a well-established fact. Those infants gain fat-free mass and protein rapidly during the first weeks of postnatal growth and require a much higher protein/energy ratio than term infants. Recommended protein intakes are 3.5-4.0 g/kg per day. For term infants, on the other hand, FAO and WHO have recently lowered recommended protein intakes to better reflect our current knowledge about the protein concentration in breast milk during the first 12 months of lactation. Longitudinal randomized clinical trials now confirm that term infants who are fed infant and follow-up formulas with protein concentrations >2.25 g/100 kcal (high protein formulas) during the first year of life grow faster than indicated by the WHO growth standards. Rapid weight gain during infancy is a predictor of childhood and adult obesity. Infants fed high protein quality formulas with protein concentrations of 1.6-2.2 g/100 kcal from 3 to 4 months onwards experience weight gain that is very close to that of breastfed infants. Biomarkers (insulin or IGF-1) of infants receiving low protein formulas differ from those of infants receiving high protein formulas. Six-year-old children who received low protein formulas in the first year of life had a lower risk of childhood obesity (BMI >95th percentile of WHO standards) compared with children who received high protein formulas as infants. BMI at 5 years of age is similar in children who were breastfed or received low protein formulas as infants. It is most important that the new low protein formulas are safe and adequate for all healthy term infants. Based on new protein technologies, the levels of essential and branched-chain amino acids in low protein formulas are now close to those in breast milk. Safety has been confirmed by following anthropometric parameters to 5-6 years of age and comparing these parameters with the WHO growth standards. Body composition measurements indicate similar protein accretion between 3 and 6 months of age in infants fed high or low protein formulas. Longitudinal data on body composition indicate that children who received a low protein formula until age 12 months gain less fat between 6 and 60 months than children who received a high protein formula. Breastfeeding and the use of low/high protein quality formulas in term infants who cannot be breastfed can help support appropriate metabolic programming during this critical period and reduce the risk of later obesity.

Postnatal High Protein Intake Can Contribute to Accelerated Weight Gain of Infants and Increased Obesity Risk

Worldwide, 38% of women are now overweight (BMI 25-30) or obese (BMI ≥30). There is increasing evidence that maternal obesity can result in unfavorable (epigenetic) pre- and postnatal programming of important genes of the offspring. Infants of overweight mothers show faster weight gain during infancy, which is associated with higher risk of obesity during childhood and adult life. This can have lifelong consequences such as increased risk of noncommunicable diseases. Many studies indicate that infants of obese and nonobese mothers who were fed traditional (high-protein) formulas gain more rapidly weight than breastfed infants. An updated meta-analysis (n = 1,150) indicates that infants from four continents who were fed a whey-based, low-protein (1.8 g/100 kcal) formula with an essential amino-acid profile closer to breast milk grow in accordance with the World Health Organization (WHO) growth standard (0-4 months). A new experimental low-protein (1.61-1.65 g protein/100 kcal) formula for infants between 3 and 12 months of age was recently tested in two randomized clinical trials. One trial in the general US population indicates lower weight between 4 and 12 months of age in infants fed the low-protein formula when compared to infants on the high-protein formula (p = 0.031). Weight gain was not inferior to the WHO growth standards. Longitudinal analysis of odds ratios from 4 to 12 months of age showed a lower incidence of infants with weight >85th percentile in the low-protein group compared with the high-protein group (p = 0.015). In the second trial, which was conducted in Chile and included infants of mothers with BMI >25, infants fed the low-protein formula gained less weight between 4 and 12 months (p = 0.022) and until 24 months (p = 0.031) than the high-protein group. Weight gain was similar to the breastfed reference group. In both trials, biomarkers of protein metabolism (insulin-like growth factor-1 and C-peptide) of the low-protein groups were closer to breastfed infants than the respective biomarkers of the high-protein groups. Health economic analyses indicate that feeding low-protein formulas to nonbreastfed infants would result in cost savings for both the individual and the society. Preventive measures against childhood and adult obesity should include promotion of breastfeeding for 6 months or longer, and use of low-protein formulas in nonbreastfed infants.

A pilot study on the application of a symptom-based score for the diagnosis of cow's milk protein allergy

Objective:

A challenge is the recommended test to diagnose cow’s milk protein allergy. However, many parents and physicians prefer to not challenge because the procedure may cause (severe) symptoms. In clinical routine, diagnostic testing is only available for IgE-mediated allergy. The aim of this study was to test the diagnostic accuracy of a symptom-based score to select infants at risk of having cow’s milk protein allergy.

Methods:

A symptom-based score was developed and consensus was reached that a score of ≥12 would select infants at risk of cow’s milk protein allergy. Diagnosis of cow’s milk protein allergy was demonstrated with a positive challenge after 1-month elimination diet.

Results:

An open challenge was performed in 85/116 (73%) infants suspected of cow’s milk protein allergy based on a symptom-based score ≥ 12 and was positive in 59/85 (69%). Although “a challenge test” was planned in the protocol, 27% of the parents refused the challenge. The mean decrease after 1 month of elimination diet with an extensive hydrolysate was −8.07 (95% confidence interval = −8.74, −7.40). If the symptom-based score during the elimination diet decreased to 6 or lower, 80% of the infants had a positive challenge test. If the symptom-based score remained >7, the challenge test was positive in only 48% (p < 0.001).

Conclusion:

In daily practice, a symptom-based score of ≥12 is a useful tool to select infants at risk of cow’s milk protein allergy. If an elimination diet reduces the symptom-based score to ≤6, the challenge test is positive in 80%.

Effect of a Growing-up Milk Containing Synbiotics on Immune Function and Growth in Children: A Cluster Randomized, Multicenter, Double-blind, Placebo Controlled Study

Common infectious diseases, such as diarrhea, are still the major cause of death in children under 5-years-old, particularly in developing countries. It is known that there is a close relationship between nutrition and immune function. To evaluate the effect of a growing-up milk containing synbiotics on immune function and child growth, we conducted a cluster randomized, multicenter, double-blind, placebo controlled clinical trial in children between 18 and 36 months of age in Vietnam. Eligible children from eight and seven kindergartens were randomly assigned to receive test and isocaloric/ isoproteic control milk, respectively, for 5 months. We found that the blood immunoglobulin A (IgA) level and growth parameters were increased in the test group. Compared to the control group, there was also a trend of decreased vitamin A deficiency and fewer adverse events in the test group. These data suggest that a growing-up milk containing synbiotics may be useful in supporting immune function and promoting growth in children.

Treating cow's milk protein allergy: a double-blind randomized trial comparing two extensively hydrolysed formulas with probiotics

AIM

The treatment for cow's milk protein allergy (CMPA) is a diet with an extensive hydrolysate. This study aimed to determine whether a whey (eWH) or casein hydrolysate (eCH) is the best option.

METHODS

Infants with suspected CMPA were treated with an eWH or eCH, and efficacy was assessed with a symptom-based score developed by the authors. Diagnosis of CMPA was based on a positive challenge. If positive, the same eHF/eCH was continued. If negative, a standard starter and follow-up formula were given up to the age of 12 months.

RESULTS

An open challenge was performed on 85/116 (73%) infants suspected of CMPA on clinical grounds and was positive in 59/85 (69%). After 1 month, the symptom-based scores in both groups showed significant statistical and clinical reductions, and total and specific IgE and skin prick test results were similar. Both hydrolysates were enriched with probiotics, which were recovered in the gastrointestinal flora. The eWH-Standard Formula sequence led to better growth at the age of 1 year than the other three feeding regimens tested.

CONCLUSION

The eWH and eCH are equally effective. The symptom-based score is a useful tool to evaluate the efficacy of dietary treatment in infants with CMPA.

The effect of acute dark chocolate consumption on carbohydrate metabolism and performance during rest and exercise

Consumption of cocoa-enriched dark chocolate (DC) has been shown to alter glucose and insulin concentration during rest and exercise compared with cocoa-depleted control (CON). However, the impact of DC consumption on exercise metabolism and performance is uncertain. Therefore, we investigated carbohydrate metabolism via stable isotope tracer techniques during exercise after subjects ingested either DC or CON. Sixteen overnight-fasted male cyclists performed a single-blinded, randomized, crossover design trial, after consuming either DC or CON at 2 h prior to 2.5 h of steady-state (SS) exercise (∼45% peak oxygen uptake). This was followed by an ∼15-min time-trial (TT) and 60 min of recovery. [6,6-(2)H2]Glucose and [U-(13)C]glucose were infused during SS to assess glucose rate of appearance (Ra) and disappearance (Rd). After DC consumption, plasma (-)-glucose and insulin concentrations were significantly (p < 0.001) elevated throughout vs. CON. During SS, there was no difference in [6,6-(2)H2]glucose Ra between treatments, but towards the end of SS (last 60 min) there was a ∼16% decrease in Rd in DC vs. CON (p < 0.05). Accordingly, after DC there was an ∼18% significant decrease in plasma glucose oxidation (trial effect; p = 0.032), and an ∼15% increase in tracer-derived muscle glycogen utilization (p = 0.045) late during SS exercise. The higher blood glucose concentrations during exercise and recovery after DC consumption coincided with high concentrations of epicatechin and (or) theobromine. In summary, DC consumption altered muscle carbohydrate partitioning, between muscle glucose uptake and glycogen oxidation, but did not effect cycling TT performance.

Effect of short-duration lipid supplementation on fat oxidation during exercise and cycling performance

The effect of intramyocellular lipids (IMCLs) on endurance performance with high skeletal muscle glycogen availability remains unclear. Previous work has shown that a lipid-supplemented high-carbohydrate (CHO) diet increases IMCLs while permitting normal glycogen loading. The aim of this study was to assess the effect of fat supplementation on fat oxidation (Fox) and endurance performance. Twenty-two trained male cyclists performed 2 simulated time trials (TT) in a randomized crossover design. Subjects cycled at ∼53% maximal voluntary external power for 2 h and then followed 1 of 2 diets for 2.5 days: a high-CHO low-fat (HC) diet, consisting of CHO 7.4 g·kg(-1)·day(-1) and fat 0.5 g·kg(-1)·day(-1); or a high-CHO fat-supplemented (HCF) diet, which was a replication of the HC diet with ∼240 g surplus fat (30% saturation) distributed over the last 4 meals of the diet period. On trial morning, fasting blood was sampled and Fox was measured during an incremental exercise; a ∼1-h TT followed. Breath volatile compounds (VOCs) were measured at 3 time points. Mental fatigue, measured as reaction time, was evaluated during the TT. Plasma free fatty acid concentration was 50% lower after the HCF diet (p < 0.0001), and breath acetone was reduced (p < 0.05) "at rest". Fox peaked (∼0.35 g·kg(-1)) at ∼42% peak oxygen consumption, and was not influenced by diet. Performance was not significantly different between the HCF and HC diets (3369 ± 46 s vs 3398 ± 48 s; p = 0.39), nor were reaction times to the attention task and VOCs (p = NS for both). In conclusion, the short-term intake of a lipid supplement in combination with a glycogen-loading diet designed to boost intramyocellular lipids while avoiding fat adaptation did not alter substrate oxidation during exercise or 1-hour cycling performance.

Evaluation of growth and early infant feeding: a challenge for scientists, industry and regulatory bodies

Growth studies are necessary to prove safety and efficacy of new or renovated infant formulas. Healthy infants need to be followed in randomized clinical trials until 4-6 months of age. Breastfed reference groups should be included in such studies, because growth of formula-fed infants may deviate from breastfed infants. The WHO growth standard describes growth of exclusively or predominantly breastfed infants and is frequently used as reference. However, the limitations of the standard must be known because weight-for-age until 6 months is higher than in all international growth references. Meta-analyses indicate that both weight and BMI of breastfed reference groups in clinical trials and of infants fed a low protein formula are somehow lower than the WHO standard. Infants of overweight and obese mothers or at risk for malnutrition are considered as at-risk populations. Any infant formula trial in those populations should use the WHO standard to document safety.

Effects of drinking supplementary water at school on cognitive performance in children

We investigated the beneficial effects of drinking supplementary water during the school day on the cognitive performance and transitory subjective states, such as fatigue or vigor, in 168 children aged between 9 and 11years who were living in a hot climate (South Italy, Sardinia). The classes were randomly divided into an intervention group, which received water supplementation, and a control group. Dehydration was determined by urine sampling and was defined as urine osmolality greater than 800mOsm/kg H(2)O (Katz, Massry, Agomn, & Toor, 1965). The change in the scores from the morning to the afternoon of hydration levels, cognitive performance and transitory subjective states were correlated. In line with a previous observational study that evaluated the hydration status of school children living in a country with a hot climate (Bar-David, Urkin, & Kozminsky, 2005), our results showed that a remarkable proportion of children were in a state of mild, voluntary dehydration at the beginning of the school day (84%). We found a significant negative correlation between dehydration and the auditory number span, which indicates a beneficial effect of drinking supplementary water at school on short-term memory. Moreover, there was a positive correlation between dehydration and performance in the verbal analogy task. The results are discussed in the light of the complexity of the neurobiological mechanisms involved in the relationship between hydration status and cognition.

Instant coffee with high chlorogenic acid levels protects humans against oxidative damage of macromolecules

SCOPE

Coffee is among the most frequently consumed beverages. Its consumption is inversely associated to the incidence of diseases related to reactive oxygen species; the phenomenon may be due to its antioxidant properties. Our primary objective was to investigate the impact of consumption of a coffee containing high levels of chlorogenic acids on the oxidation of proteins, DNA and membrane lipids; additionally, other redox biomarkers were monitored in an intervention trial.

METHODS AND RESULTS

The treatment group (n=36) consumed instant coffee co-extracted from green and roasted beans, whereas the control consumed water (800 mL/P/day, 5 days). A global statistical analysis of four main biomarkers selected as primary outcomes showed that the overall changes are significant. 8-Isoprostaglandin F2α in urine declined by 15.3%, 3-nitrotyrosine was decreased by 16.1%, DNA migration due to oxidized purines and pyrimidines was (not significantly) reduced in lymphocytes by 12.5 and 14.1%. Other markers such as the total antioxidant capacity were moderately increased; e.g. LDL and malondialdehyde were shifted towards a non-significant reduction.

CONCLUSION

The oxidation of DNA, lipids and proteins associated with the incidence of various diseases and the protection against their oxidative damage may be indicative for beneficial health effects of coffee.

Validation of the Mini Nutritional Assessment short-form (MNA-SF): a practical tool for identification of nutritional status

OBJECTIVE

To validate a revision of the Mini Nutritional Assessment short-form (MNA(R)-SF) against the full MNA, a standard tool for nutritional evaluation.

METHODS

A literature search identified studies that used the MNA for nutritional screening in geriatric patients. The contacted authors submitted original datasets that were merged into a single database. Various combinations of the questions on the current MNA-SF were tested using this database through combination analysis and ROC based derivation of classification thresholds.

RESULTS

Twenty-seven datasets (n=6257 participants) were initially processed from which twelve were used in the current analysis on a sample of 2032 study participants (mean age 82.3y) with complete information on all MNA items. The original MNA-SF was a combination of six questions from the full MNA. A revised MNA-SF included calf circumference (CC) substituted for BMI performed equally well. A revised three-category scoring classification for this revised MNA-SF, using BMI and/or CC, had good sensitivity compared to the full MNA.

CONCLUSION

The newly revised MNA-SF is a valid nutritional screening tool applicable to geriatric health care professionals with the option of using CC when BMI cannot be calculated. This revised MNA-SF increases the applicability of this rapid screening tool in clinical practice through the inclusion of a "malnourished" category.

Assessment of the safety, tolerance, and protective effect against diarrhea of infant formulas containing mixtures of probiotics or probiotics and prebiotics in a randomized controlled trial

BACKGROUND

Probiotics and prebiotics are considered to be beneficial to the gastrointestinal health of infants.

OBJECTIVE

The objective was to evaluate infant formulas containing probiotics and synbiotics (combinations of probiotics and prebiotics) for safety and tolerance.

DESIGN

In a prospective, controlled, double-blind, randomized trial, healthy full-term infants were exclusively fed a control formula or study formulas containing Bifidobacterium longum BL999 (BL999) + Lactobacillus rhamnosus LPR (LPR), BL999 + LPR + 4 g/L of 90% galactooligosaccharide/10% short-chain fructooligosaccharide (GOS/SCFOS), or BL999 + Lactobacillus paracasei ST11 (ST11) + 4 g/L GOS/SCFOS from < or = 2 to 16 wk of age (treatment period). Safety and tolerance were assessed based on weight gain during the treatment period (primary outcome) as well as recumbent length, head circumference, digestive tolerance, and adverse events (secondary outcomes), which were evaluated at 2, 4, 8, 12, 16, and 52 wk of age.

RESULTS

Two hundred eighty-four infants were enrolled. During the treatment period, difference in mean weight gain between control and study formula groups in both the intention-to-treat and per-protocol populations were within the predefined equivalence boundaries of +/-3.9 g/d, indicating equivalent weight gain. Secondary outcomes did not show significant differences between groups during the treatment period.

CONCLUSION

Infants fed formulas containing probiotics or synbiotics show a similar rate in weight gain compared with those fed a control formula and tolerate these formulas well.

Supplementation with 200 mg/day docosahexaenoic acid from mid-pregnancy through lactation improves the docosahexaenoic acid status of mothers with a habitually low fish intake and of their infants

BACKGROUND/AIMS

The supply of docosahexaenoic acid (DHA, 22:6omega-3), important for fetal/infant neurodevelopment, depends on the maternal fatty acid (FA) status, which may be marginal in central Europe. Therefore, we investigated the effect of a daily vitamin/mineral supplement with and without 200 mg DHA from mid-pregnancy through lactation on the DHA concentrations in maternal and infant red blood cell phospholipids (RBC%), and in breast milk FA (%).

METHODS

At 21 weeks' gestation, 144 women were enrolled into a randomised, double-blind clinical trial receiving daily: (1) a basic vitamin-mineral supplement (Vit/Min group), (2) Vit/Min plus 4.5 g fructo-oligosaccharide (FOS group), or (3) Vit/Min plus 4.5 g FOS plus 200 mg fish oil-derived DHA (DHA-FOS group). FAs were determined by capillary gas-liquid chromatography.

RESULTS

While maternal RBC-DHA% at enrolment was not different, at 37 weeks gestation, and 3 months after delivery RBC-DHA% were significantly higher in the DHA-FOS group. The breast milk DHA% was twice as high in the DHA-FOS group (0.50%) than in the two others (0.25 %) (p < 0.001), and the ratio ARA/DHA in the DHA-FOS group was 1.0 +/- 0.43, in the others 2.1 +/- 0.43 (p < 0.001). The RBC-DHA% of the infants in the DHA-FOS group was also significantly higher, and correlated significantly with maternal RBC-DHA% before and 3 months after delivery.

CONCLUSIONS

In central Europe, a dose of 200 mg/day DHA from mid-pregnancy through lactation seems appropriate to improve the DHA status of mothers and infants.

Clinical evaluation of a new starter formula for infants containing live Bifidobacterium longum BL999 and prebiotics

OBJECTIVES

The larger number of bifidobacteria in the intestine of breast-fed infants has been associated with their better health compared with formula-fed infants. We assessed the safety and tolerability of an experimental formula containing 2 x 10(7) colony-forming units of Bifidobacterium longum BL999 and 4 g/L of a prebiotic mixture containing 90% galacto-oligosaccharides and 10% fructo-oligosaccharides.

METHODS

A 7-mo prospective, randomized, reference-controlled, double-blinded trial was performed in infants who were not breast fed after the 14th day of birth. One hundred thirty-eight infants were enrolled and assigned to receive the control or experimental formula until they were 112 d old. Mean weight gain (primary outcome) and recumbent length, head circumference, tolerability (gastrointestinal symptoms), and overall morbidity (secondary outcomes) were measured at 14, 28, 56, 84, and 112 d of age.

RESULTS

Equivalence in mean weight gain between the two groups was shown. The treatment difference in the intention-to-treat and per-protocol populations were within the predefined equivalence boundaries of +/-3.9 g/d. No statistically significant difference in recumbent length, head circumference, or incidence of adverse events was found between the two groups. Infants in the experimental group had fewer incidences of constipation and had stool characteristics that suggest that the experimental formula was tolerated well. Furthermore, these infants showed a trend toward fewer respiratory tract infections.

CONCLUSIONS

The starter formula containing BL999 and galacto-oligosaccharides/fructo-oligosaccharides is safe and well-tolerated.

Lipoprotein phenotype and adhesion molecules correlate with diurnal triglyceride profiles in patients with coronary artery disease

BACKGROUND AND AIM

To assess the relationships between different diurnal triglyceride (TG) profiles (p) and the atherogenicity of the lipoprotein phenotype and adhesion molecule concentrations in patients with coronary artery disease (CAD).

METHODS AND RESULTS

Repeated measurements of fasting TG and TGp were made in 29 CAD patients; fasting cholesterol levels (total-C, VLDL, LDL, HDL and small dense LDL) and soluble cell adhesion molecules (sCAM) (ICAM-1 and E-selectin) were measured once. Three different TGps were defined: fasting (137.0 +/- 60.7 mg/dL) and all other TG levels <200 mg/dL (LL; n=7); a fasting TG level <200 mg/dL (147.0 +/- 49.9 mg/dL) and maximum TG levels >200 mg/dL (LH; n=13); and both fasting (225.1+/-76.2 mg/dL) and maximum TG levels >200 mg/dL (HH; n=9). We then analysed the associations between the TGp types and the lipoprotein phenotype and CAMs. LL had significantly lower values than LH (p<0.05 for all parameters except sE-selectin) and HH (p<0.05 for all parameters) of VLDL (11.2 +/- 5.8, 18.8 +/- 9.4, 28.1 +/- 8.8 mg/dL), LDL-5 (11.6 +/- 3.3, 16.4 +/- 4.5, 22.1 +/-7.9 mg/dl) and LDL-6 (12.0 +/- 3.2, 17.0 +/- 5.7, 25.7 +/- 9.6 mg/dL), sICAM-1 (209.4 +/- 30.3, 267.5 +/- 60.6, 273.4 +/- 59.1 ng/dL) and sE-selectin (25.1 +/- 17.6, 35.5 +/- 11.5, 48.5 +/- 20.2 ng/dL).

CONCLUSION

Although the differences in fasting TG levels between the LL and LH groups were not significantly different, LH had a more atherogenic lipoprotein phenotype and higher concentrations of adhesion molecules. TGp measurements seem to be suitable for identifying CAD patients with an unfavourable diurnal TG and atherosclerosis-prone lipoprotein metabolism.

Effect of an Oat Bran Enriched Diet on the Atherogenic Lipid Profile in Patients with an Increased Coronary Heart Disease Risk

AIM

To study whether an oat bran enriched diet has a specific effect in lowering total and low-density lipoprotein cholesterols, in addition to caloric and fat restriction.

METHODS

We performed a randomized, controlled, parallel-group, single-centre study in which 1,994 patients from the Wehrawald Hospital (Todtmoos, Germany) were screened and 235 met the criteria male gender, hypercholesterolemia, and overweight. All patients in the Wehrawald Hospital took part in a 4-week standardized inpatient lifestyle health program consisting of dietary intervention, increased physical activity, and health education. Caloric restriction, fat modification, and oat bran supplementation were part of the nutritional regimen within the lifestyle health program. Ninety-nine patients were randomized to a fat-modified diet with caloric restriction and a daily intake of 35-50 g oat bran and 136 patients to a fat-modified, oat bran-free diet with caloric restriction. Fifty-three male overweight but normocholesterolemic subjects were selected as controls.

RESULTS

The most significant decreases in total cholesterol (-67.7 +/- 37.2 mg/dl; p < 0.01), low-density lipoprotein cholesterol (-56.3 +/- 35.1 mg/dl; p < 0.01), and apolipoprotein B (-42.4 +/- 34.1 mg/dl; p < 0.01) were found with the combination of the fat-modified and oat bran enriched food.

CONCLUSIONS

Added to a fat-modified diet, oat bran within a practical range of intake significantly reduces total cholesterol, low-density lipoprotein cholesterol, and apolipoprotein B. These beneficial effects occurred independent of covariables such as physical activity or caloric and fat restriction in the diet.

Size and blood flow of central and peripheral arteries in highly trained able-bodied and disabled athletes

In a cross-sectional study, central and peripheral arteries were investigated noninvasively in high-performance athletes and in untrained subjects. The diastolic inner vessel diameter (D) of the thoracic and abdominal aorta, the subclavian artery (Sub), and common femoral artery (Fem) were determined by duplex sonography in 18 able-bodied professional tennis players, 34 able-bodied elite road cyclist athletes, 26 athletes with paraplegia, 17 below-knee amputated athletes, and 30 able-bodied, untrained subjects. The vessel cross-sectional areas (CSA) were set in relation to body surface area (BSA), and the cross-section index (CS-index = CSA/BSA) was calculated. Volumetric blood flow was determined in Sub and Fem via a pulsed-wave Doppler system and was set in relation to heart rate to calculate the stroke flow. A significantly increased D of Sub was found in the racket arm of able-bodied tennis players compared with the opposite arm (19%). Fem of able-bodied road cyclist athletes and of the intact limb in below-knee amputated athletes showed similar increases. D of Fem was lower in athletes with paraplegia (37%) and in below-knee amputated athletes proximal to the lesion (21%) compared with able-bodied, untrained subjects; CS-indexes were reduced 57 and 31%, respectively. Athletes with paraplegia demonstrated a larger D (19%) and a larger CS-index in Sub (54%) than able-bodied, untrained subjects. No significant differences in D and CS-indexes of the thoracic and abdominal aorta were found between any of the groups. The changes measured in Sub and Fem were associated with corresponding alterations in blood flow and stroke flow in all groups. The study suggests that the size and blood flow volume of the proximal limb arteries are adjusted to the metabolic needs of the corresponding extremity musculature and underscore the impact of exercise training or disuse on the structure and the function of the arterial system.

Hematological indices and iron status in athletes of various sports and performances

PURPOSE

Alterations of the red blood cell system and iron metabolism can influence physical performance. On the other hand, exercise can influence hematological variables. The purpose of this epidemiological study was to investigate the characteristics of the red blood cell system and the iron metabolism in athletes of different sporting disciplines and at different levels of performance.

METHODS

We studied 851 male subjects (747 athletes, 104 untrained controls). Hemoglobin (Hb), hematocrit (Hct), red blood cell count (RBC), iron, transferrin, ferritin (Fer), and haptoglobin were analyzed in standardized blood samples, obtained after 2 d of rest, considering levels of performance (internationally, nationally, locally competitive, and leisure time), distinctive sporting category (endurance- (END), strength- (POW), and mixed-trained (MIX)), and, within endurance athletes, distinctive disciplines (cycling (CYC) and running (RUN)).

RESULTS

No difference was found between athletes and controls in Hb and Hct. Reduced Hb, Hct, and RBC levels were observed in END compared with POW and MIX. These findings can mainly be attributed to exercise-induced plasma volume expansion, and only to a lesser degree and in selected athlete populations to hemolysis, as low haptoglobin is only observed in RUN, not in CYC, suggesting that not exercise itself but the "traumatic" movement of running might trigger the destruction of red blood cells. Physical activity of increasing duration and workloads (leisure time compared with competitive athletes) leads to decreased Fer levels in athletes, disregarding their discipline, but more pronounced in RUN.

CONCLUSION

Physical training itself has no significant effect on selected hematological variables in athletes compared with untrained controls. The specific type and duration of exercise is of major importance in the adaptations of the blood cell system and the iron metabolism.

Upper respiratory tract infection in athletes: influence of lifestyle, type of sport, training effort, and immunostimulant intake

Epidemiological evidence suggests that heavy acute or chronic exercise is related to an increased incidence of upper respiratory tract infections in athletes, while moderate exercise is believed to be protective. During the past years, many groups have investigated the association between changes within the immune system and exercise at different intensity levels. Although following strenuous exercise, some immunologic alterations were quite consistent and reproducible, e.g. neutrophilia, lymphopenia, and depression of natural killer cell activity, some findings were divergent or strongly dependent on the study design and athletes investigated. Lately, interesting results in the field of psychoneuroimmunolgy as well as new insights in the relationship between macro- and micronutrient and the immune system have brought up new fields of research interest. There is growing evidence that e.g. lifestyle factors, the coping with daily stress, and dietary behavior are important cofactors in the immune response to exercise. The present work gives a short review on the literature dealing with URTI in athletes with special reference to the above mentioned cofactors. In addition, the results of a recent investigation concerning training and associated lifestyle patterns in German athletes are presented.

Haemoglobin, haematocrit and red blood cell indices in elite cyclists. Are the control values for blood testing valid?

BACKGROUND

In international cycling and cross-country skiing competitions, blood tests are used to unmask the performance enhancing misuse of erythropoietin. Haematocrit (cycling) and haemoglobin (cross-country skiing) limits have been set by international sporting federations (haematocrit 50%, haemoglobin 18.5 g/dl). Athletes tested above these cut-off values are declared unfit for competition. To investigate the validity of these regulations, we studied haemoglobin, haematocrit and red blood cell indices of elite cyclists before erythropoietin became commercially available.

MATERIAL AND METHODS

We investigated 523 blood samples of 92 male elite cyclists (age 16-31 years) from 1978 to 1987. Haematocrit, haemoglobin and red blood cell count were analysed automatically, erythrocyte indices were calculated.

RESULTS

Haemoglobin (-0.3 +/- 1 g/dl), haematocrit (-1.2 +/- 2.8%) and red blood cell count (-0.2 +/- 0.4 x 10(6)/mm3) decreased significantly (p < 0.05) with increasing training workload. The erythrocyte indices showed no significant change. Fifty-four blood samples (10.3%) showed a haematocrit above 50%, one sample presented a haemoglobin mass higher than 18.5 g/dl. During periods of increased workload, less athletes tested above the haematocrit limit.

CONCLUSION

The current haematocrit limit used in blood tests might lead to a high number of false positive tests.

Concurrent reductions of serum leptin and lipids during weight loss in obese men with type II diabetes

The aim of the study was to examine the effects of weight reduction by exercise and diet on metabolic control in obese subjects with insulin resistance, particularly investigating if changes in serum leptin concentrations were directly associated with improvements in metabolic control. Twenty obese men (48 +/- 8 yr; body mass index 32. 1 +/- 3.9 kg/m(2)) with previously diagnosed type II diabetes mellitus were assigned to a 4-wk intervention program of exercise (2, 200 kcal/wk) and diet (1,000 kcal/day; 50% carbohydrates, 25% protein, 25% fat; polyunsaturated-to-saturated fatty acid ratio 1.0). Intervention induced significant reductions in body weight and serum leptin levels, and improvements in lipoprotein profile and glucose control. Reductions in leptin levels were directly associated with reductions in serum triglycerides and cholesterol, a finding that was independent of improvements in glucose control. These data show that serum leptin concentrations can be reduced with caloric restriction and exercise in male patients with type II diabetes, and they suggest a direct relationship between leptin and lipoprotein metabolism that is not solely due to weight reduction.

[Freiburg Questionnaire of physical activity--development, evaluation and application]

Aim of the present study was to design a questionnaire to assess health related physical activity, to validate the instrument and to apply it to a population sample. Reliability of the questionnaire was evaluated by test-retest investigations with intervals of two weeks and six months. High correlations between the repeated administrations reflect a good reliability of our instrument. Only gardening and cycling, as well as the depending basic and total activity, showed typically seasonal variations. Validity was established by correlating physical activity data with maximum oxygen uptake. Maximum oxygen uptake correlated with sport activities (partial correlation coefficient: r = 0.422, p < 0.01). Evaluated data were consistent. People rating themselves as "more active than their coevals" were indeed more active in sport (r = 0.334, p < 0.01) and total activity (r = 0.282, p < 0.05). Studying activity patterns of a population sample of adult residents of Freiburg (systematic random sampling, n = 612, 20-98 years) we found total physical activity of 9.2 hours per week (median), with activities of low to moderate intensities dominating. Age and gender are important determinants of the activity patterns. According to the recommendation of Paffenbarger (2000 kcal/week total physical activity) 40% of the residents of Freiburg did not reach the recommended energy expenditure. Compared to the recommendation of the American College of Sports Medicine (1000 kcal/week by training) 63% of the population sample were not active enough.

Relation of leisure-time physical activity to structural and functional arterial properties of the common carotid artery in male subjects

The structure and function of central arteries are altered with advancing age. These changes comprise arterial dilation, intima-media thickening and increase in stiffness. Arterial wall hypertrophy and increased stiffness are associated with major cardiovascular disease. In contrast to this, physical activity has been found to be inversely related to the incidence of major cardiovascular disease and mortality in humans. However, conflicting data exist on the effect of physical activity on arterial stiffness and very little data about its association with structural arterial properties. We therefore investigated the association of the self-selected leisure-time physical activity (LTPA), assessed by a self-administered questionnaire, with the structure and function of the common carotid artery, examined with high-resolution ultrasound, in 51 male subjects aged between 16 and 78 years. We found that men with a higher level of LTPA (> 38.1 MET*h/week = H-LTPA) (metabolic equivalent value; 1 MET= energy expended by a person at rest, i.e. approximately 3.5 ml oxygen uptake/kg body mass or 1 kcal/kg per h) had a significantly lower arterial stiffness (P = 0.02) than men with lower levels ( < 38.1 MET*h/week = L-LTPA) (4.32+/-1.17 versus 5.75+/-1.21 x 10(6) cm(-2)). In multiple regression analyses, with several atherosclerotic risk factors as correlating variables with arterial stiffness, LTPA persisted as an independent predictor of arterial stiffness (adjusted R2=0.19) in addition to apolipoprotein B level (adjusted R2 = 0.33). The study could not, however, show an association of LTPA with reduced intima-media thickness (L-LTPA = 0.66+/-0.15 versus H-LTPA 0.66+/-0.14) or arterial dilation of diastolic diameter (L-LTPA = 6.34 + 0.64 versus H-LTPA 6.08+/-0.69). However, the positive association of LTPA with several parameters, which correlated inversely with intima-media thickness, may be taken as an indicator for a possible positive (not visible in an ultrasonic examination of the common carotid artery) effect of LTPA on the arterial wall structure.

Influence of 4 weeks' intervention by exercise and diet on low-density lipoprotein subfractions in obese men with type 2 diabetes

Insulin resistance is associated with dyslipoproteinemia characterized by increased serum triglycerides, reduced high-density lipoprotein 2 (HDL2) cholesterol, and increased small, dense low-density lipoprotein (LDL) subfraction particles. Physical activity and weight reduction are known to improve insulin resistance and dyslipoproteinemia, but their influence on LDL subfractions in diabetic patients is unknown. Therefore, we investigated the effect of a 4-week intervention program of exercise (2,200 kcal/wk) and diet (1,000 kcal/d: 50% carbohydrate, 25% protein, and 25% fat; polyunsaturated/saturated fat ratio, 1.0) on glycemic control and HDL and LDL subfractions in 34 obese patients with non-insulin-dependent diabetes (age, 49 +/- 9 years; body mass index [BMI], 33.1 +/- 5.1 kg/m2). Reductions in body weight (P < .001) and improvements in fasting blood glucose, insulin, fructosamine (P < .001), and free fatty acids (P < .01) by intervention were associated with reductions in serum cholesterol and apolipoprotein B (apo B) concentrations in very-low-density lipoprotein (VLDL) (P < .01), intermediate-density lipoprotein (IDL), and small, dense (>1.040 g/mL) LDL particles (P < .001). These data underlie the positive influence of weight reduction induced by exercise and diet on insulin resistance and lipoprotein metabolism in obese diabetic patients, particularly showing improvements of the LDL subfraction profile with a decrease of small, dense LDL particles. This is of particular importance, as these particles have been shown to be associated with coronary artery disease.

Structural, functional, and hemodynamic changes of the common carotid artery with age in male subjects

Aging of the common carotid artery (CCA) is associated with different principal structural, functional, and hemodynamic changes, which are often influenced by several atherosclerotic risk factors, so that it is difficult to estimate the exclusive effect of aging on this process. Studies dealing with vascular aging of the CCA usually assess only single, dimensional, or functional parameters, although it is likely that there are interactions and probably differences between them. Moreover, regional vascular blood flow characteristics are often not taken into consideration. Therefore, the aim of the study was to assess the age-related multiparametric changes of the CCA properties with ultrasound in 69 male subjects between the ages of 16 and 75 (42.4+/-16.5 years), who were screened for the absence of major atherosclerotic risk factors or existing vascular disease. As a result, the intima media thickness (0.052 mm/10 y) and diastolic diameter (0.17 mm/10 y) increased nearly linearly with age (r=0.60, P<0.001; and r=0.46, P<0.001, respectively). The absolute diastolic/systolic diameter change diminished by 0.10 mm/10 y (r=-0. 73, P<0.001) and peak expansion velocity dropped by 0.12 cm/s per 10 years (r=-0.62, P<0.001) highly significantly with age. The peak blood flow velocity decreased continuously with age (r=-0.67, P<0. 00) by 9.3 cm/s per 10 years. According to multiple regression analysis, peak blood flow velocity seems to reflect the changes of several structural and functional parameters in one; intima-media thickness was determined by diastolic arterial diameter and age as independent variables. The data indicate that a multiparametric assessment may contribute to a better understanding of vascular aging and might be the basis for further studies to evaluate the association of atherosclerotic risk factors and/or major vascular disease with local changes in the CCA.

Catecholamines, heart rate, and oxygen uptake during exercise in persons with spinal cord injury

The purpose of this study was to investigate the influence of different injury levels in persons with spinal cord injury (SCI) on epinephrine (Epi) and norepinephrine (NE) at rest and during graded wheelchair exercise and the related changes in heart rate and O2 uptake (VO2). Twenty tetraplegics (Tetra), 10 high-lesion paraplegics (HLPara), 20 paraplegics with SCI below T5 (MLPara), and 18 able-bodied, nonhandicapped persons (AB) were examined. Because of the higher level of interruption of the sympathetic pathways, Tetra persons showed lower Epi and NE at rest and only slight increases during exercise compared with all other groups; the Tetra subjects' impaired cardiac sympathetic innervation caused restricted cardioacceleration and strongly reduced maximal VO2. When compared with AB persons, HLPara had comparable NE but lower Epi levels as a result of partial innervation of the noradrenergic system and denervation of the adrenal medulla. MLPara subjects showed an augmented basal and exercise-induced upper spinal thoracic sympathetic activity compared with AB subjects. The increase in heart rate in relation to VO2 was higher in HLPara because of a smaller stroke volume as a result of venous blood pooling. The different exercise response in persons with SCI is a result of the interruption of pathways in the spinal cord to the peripheral sympathetic nervous system in addition to the motor paralysis.