The role of research--how much is enough?

A great deal of research is involved in bringing PARNUTs to the marketplace. Research often begins with identifying an unfilled nutritional need, determining if that need is great enough to warrant development of a new product, and then evaluating the efficacy and safety of the potential product in animal models and clinical trials. This approach tends to emphasize short-term outcomes, however, while neglecting the issues of whether a product offers long term benefit or holds long term risks. This article presents discussion centered around the need for selecting appropriate outcomes for nutritional intervention trials, designing trials with a follow-up time sufficient to allow for outcome measurement, and enrolling a patient population large enough to accurately gauge efficacy and tolerability.

Within pair association between birth weight and blood pressure at age 8 in twins from a cohort study

OBJECTIVES

To study the association between birth weight and blood pressure in children from multiple pregnancies (multiplets), mostly twins, to determine whether maternal or genetic factors are responsible for the association.

DESIGN

Cohort study.

SETTING

Southern Tasmania.

SUBJECTS

888 children including 104 multiplets (32 monozygotic, 72 dizygotic).

MAIN OUTCOME MEASURE

Systolic blood pressure (mm Hg).

RESULTS

Blood pressure decreased with birth weight and increased with current body mass. After adjustment for age and body mass, systolic blood pressure changed by -1.94 mm Hg (95% confidence interval -2.89 to -0.98) per 1 kg increase in birth weight of singletons. For multiplets, blood pressure changed by -7.0 mm Hg (-10.1 to -3.9) for each 1 kg increase in birth weight. This was little altered in within pair analyses (-5.3, -13.8 to 3.2) and was similar for both monozygotic (-6.5, -22.5 to 9.4) and dizygotic (-4.9, -15.8 to 6.0) pairs.

CONCLUSION

Because the association between birth weight and blood pressure was largely unchanged in within pair analyses, exposures originating in the mother (such as nutritional status) cannot be wholly responsible. The association also remained within monozygotic pairs, suggesting that genetic predisposition is not wholly responsible either. The principal causal pathway must concern mechanisms within the fetoplacental unit. The stronger association in multiplets suggests that factors adversely influencing both blood pressure and birth weight are more prevalent in multiple pregnancies.

Double-blind, randomized trial of a synthetic triacylglycerol in formula-fed term infants: effects on stool biochemistry, stool characteristics, and bone mineralization

BACKGROUND

The low sn-2 palmitate content of infant formulas results in formation of fatty acid calcium soaps in the stools and reduced calcium absorption.

OBJECTIVE

Our objective was to test the hypotheses that increasing the proportion of sn-2 palmitate in formula for term infants would result in greater skeletal mineral deposition and reduced stool hardness.

DESIGN

Healthy term neonates were randomly assigned to receive standard formula (n = 103) or formula containing 50% sn-2 palmitate (high-sn-2 formula; n = 100) for 12 wk. One hundred twenty breast-fed infants were also studied. The main outcome measures were 1) radial (single-photon absorptiometry) and whole-body (dual-energy X-ray absorptiometry) bone mineral content (WBBMC) at 12 wk and 2) stool frequency, volume, and consistency at 6 and 12 wk. Secondary outcome measures included stool fatty acid content.

RESULTS

Infants receiving high-sn-2 formula had higher WBBMC (128.1 +/- 9.7 compared with 122.7 +/- 10.1 g, adjusted for size and sex), softer stools at 6 and 12 wk, and a lower proportion of stool soap fatty acids than did infants receiving the control formula. Breast-fed infants had adjusted WBBMC values (128.3 +/- 9.1 g) similar to those of infants fed high-sn-2 formula and significantly higher than those of infants fed the control formula.

CONCLUSIONS

Changing the stereoisomeric structure of palmitate in infant formula resulted in higher WBBMC, reduced stool soap fatty acids, and softer stools more like those of breast-fed infants. The greater bone mass measured could be important if it persists beyond the trial period; this merits further investigation.

Iron fortified follow on formula from 9 to 18 months improves iron status but not development or growth: a randomised trial

AIMS

Iron deficiency anaemia is associated, in observational studies, with developmental disadvantage. This study tested the hypothesis that feeding iron supplemented formula from 9 to 18 months of age would improve developmental performance.

SUBJECTS AND METHODS

493 healthy children aged 9 months being fed pasteurised cows' milk were recruited from three UK centres. They were randomised to: cows' milk as before, formula containing 0.9 mg/litre iron, or formula containing 1.2 mg/litre iron, until 18 months of age. Bayley mental and psychomotor developmental indices were measured at 18 months, as were growth and haematological indices.

RESULTS

Children fed iron fortified formula had higher plasma ferritin concentrations, but there were no significant intergroup differences in development or growth.

CONCLUSIONS

There are no developmental or growth advantages in children given iron supplemented formula, but a benefit for a minority who were anaemic, or the possibility that a benefit may emerge at a later age, cannot be excluded.

Dietary fibre, exercise and serum lipids and lipoprotein cholesterols in 12 to 15 year olds

Serum lipid and lipoprotein cholesterol levels track from childhood and are associated with risk of coronary heart disease. There is some evidence that these are influenced by dietary intake and exercise. Serum lipid and lipoprotein cholesterols were measured in a cohort of 119 British children aged 12-15 y who completed a dietary assessment and exercise questionnaire. The ratio of total- to high-density lipoprotein cholesterol fell with increasing fibre intake, but after adjustment for age, body mass index, sex and other dietary factors, this was not statistically significant. Children exercising at least once a day had significantly lower serum total cholesterol and low density lipoprotein cholesterol levels than those exercising less frequently, even after adjustment for the above factors and dietary fibre intake. No dietary factor was significantly associated with any lipid measure after adjustment for the above factors. The challenge is how to optimize exercise level in adolescent children.

Randomised trial of early diet in preterm babies and later intelligence quotient

OBJECTIVES

To determine whether perinatal nutrition influences cognitive function at 7 1/2 - 8 years in children born preterm.

DESIGN

Randomised, blinded nutritional intervention trial. Blinded follow up at 7 1/2 - 8 years.

SETTING

Intervention phase in two neonatal units; follow up in a clinic or school setting.

SUBJECTS

424 preterm infants who weighed under 1850 g at birth; 360 of those who survived were tested at 7 1/2 - 8 years.

INTERVENTIONS

Standard infant formula versus nutrient enriched preterm formula randomly assigned as sole diet (trial A) or supplements to maternal milk (trial B) fed for a mean of 1 month.

MAIN OUTCOME MEASURES

Intelligence quotient (IQ) at 7 1/2 - 8 years with abbreviated Weschler intelligence scale for children (revised).

RESULTS

There was a major sex difference in the impact of diet. At 7 1/2 - 8 years boys previously fed standard versus preterm formula as sole diet had a 12.2 point disadvantage (95% confidence interval 3.7 to 20.6; P<0.01) in verbal IQ. In those with highest intakes of trial diets corresponding figures were 9.5 point disadvantage and 14.4 point disadvantage in overall IQ (1.2 to 17.7; P<0.05) and verbal IQ (5.7 to 23.2; P<0.01). Consequently, more infants fed term formula had low verbal IQ (<85): 31% versus 14% for both sexes (P=0.02) and 47% versus 13% in boys P=0.009). There was a higher incidence of cerebral palsy in those fed term formula; exclusion of such children did not alter the findings.

CONCLUSIONS

Preterm infants are vulnerable to suboptimal early nutrition in terms of their cognitive performance--notably, language based skills--at 7 1/2 - 8 years, when cognitive scores are highly predictive of adult ones. Our data on cerebral palsy generate a new hypothesis that suboptimal nutritional management during a critical or plastic early period of rapid brain growth could impair functional compensation in those sustaining an earlier brain insult. Cognitive function, notably in males, may be permanently impaired by suboptimal neonatal nutrition.

Nutrition and cognitive development

There has been recent intense interest in the possibility that infants receiving a dietary supply of docosahexaenoic acid (DHA), either in breast milk or in a supplemented formula, may perform better on developmental tests than other infants. The only way to resolve this issue is in randomized trials in formula-fed babies, comparing those fed DHA-supplemented versus unsupplemented milks. To date most trials have been small; some also had methodological problems and results have been conflicting. The possible reasons for conflicting results in studies of both term and preterm born infants are discussed.

Infant feeding and maternal concerns about stool hardness

From a questionnaire completed by 195 mothers of infants aged 3-12 weeks we found that significantly more formula than breast-feeding mothers had concerns about stool hardness and had sought professional advice, resulting in both increased use of health care resources and more dietary interventions.

Aluminum neurotoxicity in preterm infants receiving intravenous-feeding solutions

BACKGROUND

Aluminum, a contaminant of commercial intravenous-feeding solutions, is potentially neurotoxic. We investigated the effect of perinatal exposure to intravenous aluminum on the neurologic development of infants born prematurely.

METHODS

We randomly assigned 227 premature infants with gestational ages of less than 34 weeks and birth weights of less than 1850 g who required intravenous feeding before they could begin enteral feeding to receive either standard or specially constituted, aluminum-depleted intravenous-feeding solutions. The neurologic development of the 182 surviving infants who could be tested was assessed by using the Bayley Scales of Infant Development at 18 months of age.

RESULTS

The 90 infants who received the standard feeding solutions had a mean (+/-SD) Bayley Mental Development Index of 95+/-22, as compared with 98+/-20 for the 92 infants who received the aluminum-depleted solutions (P=0.39). In a planned subgroup analysis of infants in whom the duration of intravenous feeding exceeded the median and who did not have neuromotor impairment, the mean values for the Bayley Mental Development Index for the 39 infants who received the standard solutions and the 41 infants who received the aluminum-depleted solutions were 92+/-20 and 102+/-17, respectively (P=0.02). The former were significantly more likely (39 percent, vs. 17 percent of the latter group; P=0.03) to have a Mental Development Index of less than 85, increasing their risk of subsequent educational problems. For all 157 infants without neuromotor impairment, increasing aluminum exposure was associated with a reduction in the Mental Development Index (P=0.03), with an adjusted loss of one point per day of intravenous feeding for infants receiving the standard solutions.

CONCLUSIONS

In preterm infants, prolonged intravenous feeding with solutions containing aluminum is associated with impaired neurologic development.

The influence of early diet on later development

The possibility that early nutrition has long term consequences in man has been much debated. There have been limited opportunities to perform formal randomised studies on the effect of early nutrition in man and many studies have been flawed by problems with study design. Infants born preterm are a special group. At the start of this study in 1982 evidence on which to base choice of diet was inconsistent and related only to short term outcome, and diets available for such babies differed greatly in nutrient content. In this group it was both ethical and practical to conduct a formal, randomised trial of early diet and outcome and the results were clearly for management decisions. A long term prospective outcome study was undertaken on 926 preterm infants randomly assigned to the diet received in the neonatal period. Surviving children have been followed at 9 months, 18 months, and now 7 1/2-8 years of age. The findings suggest that children fed a nutrient supplemented preterm formula perform better than those fed a standard formula milk, and also that human milk may contain factors which promote brain growth or development. Outcome data from the randomised trials show that a very brief period of dietary manipulation (on average for the first 4 weeks of life) influences later development.

Randomized outcome trial of human milk fortification and developmental outcome in preterm infants

Despite potential benefits, human milk may fail to meet preterm infants' nutrient requirements. We tested the hypothesis that fortified breast milk, fed alone or with preterm formula, would improve neurodevelopment and growth at 18-mo follow-up without adverse short-term clinical or biochemical consequences. Two hundred seventy-five preterm infants from two medical centers (birth weight < 1850 g; mean gestation 29.8 +/- 2.7 wk) whose mothers chose to provide breast milk were randomly assigned to receive for a mean of 39 d a multinutrient fortifier or control supplement containing phosphate and vitamins. Breast milk comprised 47.6% and 46.4% of enteral intake in fortified and control groups, respectively; preterm formula supplements were used when insufficient breast milk was available. Overall, there were no significant growth advantages with fortification; although, when breast milk exceeded 50% of intake, fortification promoted faster weight gain (an advantage of 1.6 g.kg-1.d-1; 95% CI: 0.1, 3.1; P < 0.05). Compared with control infants, the fortified group showed 1) higher plasma urea from week 2 (P = 0.04), 2) higher plasma calcium (mean 2.34 +/- 0.01 compared with 2.27 +/- 0.02 mmol/L; P = 0.003), 3) a greater rise in alkaline phosphatase by week 6 (P = 0.04), 4) more clinical infections (suspected plus proven; 43% compared with 31%, P = 0.04), 5) a nonsignificantly increased incidence of necrotizing enterocolitis (5.8% compared with 2.2%, P = 0.12), and 6) higher white cell and platelet counts. Developmental scores at 18 mo were slightly but not significantly higher in the fortified group. This study confirmed that breast milk fortifiers can improve short-term growth (when breast milk intakes are high); but beneficial effects on long-term development remained unproven. Future research is required to evaluate potential adverse consequences and explore more optimal fortification strategies.

Early diet of preterm infants and bone mineralization at age five years

Bone disease with significantly reduced bone mineralization is common in preterm infants, and associated with later linear growth stunting at 18 months of age. Dietary insufficiency of calcium and phosphorus is thought to be the principal aetiological factor. We studied 54 children at mean age 5 years who were born preterm and had participated in a prospective multicentre study of effects of early diet on later growth and development. Diets compared were banked donor breast milk and preterm formula fed as a supplement to mother's own milk. Increasing human milk intake was strongly positively associated with later bone mineral content. Children fed predominantly human milk had greater bone mineral content than children of similar size born at term. These data suggest that the early nutritional environment of the preterm infant could play an important role in determining later skeletal growth and mineralization.

Morphology and neuropathology of the pelvic floor in patients with stress incontinence

Urinary incontinence imposes a considerable workload on urological and gynecological practice. Many treatments exist, but recurrent stress incontinence remains a significant problem and the reasons remain unclear. Pathological and electrophysiological studies have shown that significant pelvic nerve damage and consequent denervation and reinnervation are associated with stress incontinence, and furthermore there are collagenous changes in the pelvic floor which are related to childbirth, endogenous hormone changes and the effects of increasing age. These changes include increased nerve fiber density and pudendal nerve terminal motor latency, hypertrophy of fiber types 1 and 2, type 1 fiber predominance and fiber type grouping. Connective tissue changes involve a reduction in hydroxyproline excretion, increased cross-linking and increased muscle collagen. It is only through a better understanding of the anatomy and pathophysiology of the pelvic floor that we will be able to improve outcome in women with stress incontinence and identify patients that may not be appropriate for surgical therapy. This paper reviews recent advances in the understanding of the etiology of stress incontinence.

Should doctors be more proactive as advocates for victims of violence?

Currently the management of adult victims of violence by general practitioners and accident and emergency departments is reactive, concerned almost exclusively with the management of physical injuries. Professor Jonathan Shepherd outlines some ideas for a more proactive approach on the part of doctors to improve the protection and support of vulnerable people; to deal with psychological sequelae; to take the responsibility of making an official complaint to the police away from seriously injured people, who are unable to give or withhold consent to disclosure; and to prevent assailants inflicting further injuries. We asked a sociologist, a psychiatrist, a moral philosopher, and a police surgeon for their comments.

Maternal smoking and blood pressure in 7.5 to 8 year old offspring

Reduced fetal growth in babies born preterm may be associated with reduced later blood pressure, but in children born at term, higher blood pressure. It was hypothesised, therefore, that maternal smoking in pregnancy, associated with reduced fetal growth, programmes later blood pressure differentially according to length of gestation. Six hundred and eighteen children born preterm and now aged 7.5 to 8 years were studied prospectively. Systolic blood pressure in children from smoking compared with non-smoking mothers was significantly lower in those born before 33 weeks' gestation and significantly higher in those born at 33 or more weeks. Within the range 0-40 cigarettes per day until delivery (after adjusting for potentially confounding factors, including social class and current weight) each 10 was associated with a 1.5 mm Hg fall and 2.9 mm Hg rise in pressure for children born below or above 33 weeks' gestation respectively. Similar though smaller differences were seen in diastolic pressure. These data support our hypothesis that later effects of insults impairing fetal growth are gestation dependent, and provide the first evidence that maternal smoking may have long term consequences for blood pressure in children.

Comparison of cerebral blood flow velocity estimation with cranial ultrasound imaging for early prediction of outcome in preterm infants

Seventy-four low birth weight infants underwent serial measurements of cerebral blood flow velocity (CBFV) using Doppler ultrasound together with ultrasound imaging of the brain. Surviving infants were examined and assessed using the Bayley scales of mental and motor development at 18 months post-term. There were no significant differences in mean CBFV between normal and impaired infants. Infants with abnormal neurological signs (n = 6) or developmental delay (n = 3) did not show the usual steady rise in CBFV during the first few days of life. Four of nine had a rise, then a fall in CBFV compared with 4 of 31 with complete data in the normal group. This difference is significant (chi 2 = 4.3, p = 0.03). The magnitude of the percentage increase between day 1 and day 3 was also smaller in the abnormal group (median 0% vs. 39%, Mann-Whitney p = 0.03). A structural abnormality seen on the cranial ultrasound image was a better predictor of adverse outcome than an abnormal CBFV pattern, with a better sensitivity and specificity (66% and 97% for imaging compared to 44% and 87% for CBFV). The addition of serial ultrasound Doppler measurements of CBFV did not improve the prediction of outcome obtained using ultrasound imaging alone.

Handedness in blood donors: no association with blood group or twinning

There has been considerable interest in the contribution of inheritance to determination of handedness and in observed associations between hand laterality and twinning, gender and age. Unpublished data from a study of children born preterm suggested an association between AB0 blood group and handedness. A questionnaire filled in by 3815 blood donors, gave information on blood group, age, gender, whether they were a twin, hand used for writing and perceived handedness. There was no association between AB0 blood group or rhesus group and handedness. Significantly more females than males considered themselves right handed (82.5% versus 79.9%) and more subjects aged 50+ wrote with the right hand (90.6% versus 87.6% if younger). Twins did not differ from other subjects in this study and we hypothesise that the generally inconsistent findings relating to twins may be explained by population differences in the proportion of twins born preterm.

Influence of early diet on outcome in preterm infants

Despite intensive research in infant nutrition over the past 50 years, uncertainty exists in nearly every major area of practice. A key factor in this uncertainty has been the lack of knowledge on whether diet or nutritional status in early life has a long-term or permanent influence on health, growth or performance. The possibility that early nutrition has long-term consequences in man has been much debated. There have been limited opportunities to perform formal randomized studies on the effect of early nutrition in humans and many studies have been flawed by problems with study design. Infants born preterm are a special group. At the start of our study in 1982, evidence on which to base choice of diet was inconsistent and related only to short-term outcome, and diets available for such babies differed greatly in nutrient content. In this group it was both ethical and practical to conduct a formal, randomized trial of early diet and outcome and the results were clearly needed for management decisions. We have undertaken a long-term prospective outcome study on 926 preterm infants randomly assigned to the diet received in the neonatal period. Surviving children have been followed at 9 months, 18 months and now 7.5-8 years of age. Our findings suggest that human milk may contain factors which promote brain growth or development and also bone mineralization later in childhood. Outcome data from the randomized trials show that a very brief period of dietary manipulation (on average for the first 4 weeks of life) influences later development.