Long-term effects of neonatal sodium restriction on blood pressure

Health consequences of nutrition in childhood and early infancy

Medical and scientific studies have proven that the body's metabolic programming can be influenced by diet and nutrition from early infancy. As a result, the incidence and outcome of several metabolic diseases such as obesity, hypertension and cardiovascular disorders have been found to be associated with birth weight, growth and feeding patterns, and the body composition in early childhood. Exclusive or partial breast feeding for at least 6 months is recommended by the World Health Organization, while the European Society of Pediatric Gastroenterology Hepatology and Nutrition Committee on Nutrition recommends the introduction of complementary foods at 4-6 months of age. The fat content of the diet should not be below 25% of the energy intake in order to maintain ideal growth while dietary proteins above 15% of the energy intake is related to future obesity. Long term benefits of breast feeding include a more ideal serum lipid profile and blood pressure, improved neuro-cognitive scores, and a decreased incidence for atopic dermatitis in children who have family members with atopic diseases. Several studies have also acknowledged the long term benefits for neuro-cognitive development from certain nutrients including long-chain polyunstaturated fatty acids and docosahexaenoic acid. Meat intake has proved to be beneficial to psychomotor development. It is suggested that early introduction for complementary foods before 4 months of age is a risk factor for atopic dermatitis; while no strong evidence showed delaying weaning foods can decrease the risk for allergic diseases.

Breast-feeding: A commentary by the ESPGHAN Committee on Nutrition

This medical position article by the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition summarises the current status of breast-feeding practice, the present knowledge on the composition of human milk, advisable duration of exclusive and partial breast-feeding, growth of the breast-fed infant, health benefits associated with breast-feeding, nutritional supplementation for breast-fed infants, and contraindications to breast-feeding. This article emphasises the important role of paediatricians in the implementation of health policies devised to promote breast-feeding.The European Society for Paediatric Gastroenterology, Hepatology, and Nutrition Committee on Nutrition recognises breast-feeding as the natural and advisable way of supporting the healthy growth and development of young children. This article delineates the health benefits of breast-feeding, reduced risk of infectious diarrhoea and acute otitis media being the best documented. Exclusive breast-feeding for around 6 months is a desirable goal, but partial breast-feeding as well as breast-feeding for shorter periods of time are also valuable. Continuation of breast-feeding after the introduction of complementary feeding is encouraged as long as mutually desired by mother and child.The role of health care workers, including paediatricians, is to protect, promote, and support breast-feeding. Health care workers should be trained in breast-feeding issues and counselling, and they should encourage practices that do not undermine breast-feeding. Societal standards and legal regulations that facilitate breast-feeding should be promoted, such as providing maternity leave for at least 6 months and protecting working mothers.

Screening for kidney disease in children on World Kidney Day in Jalisco, Mexico

World Kidney Day (WKD) is intended to raise awareness and increase detection of chronic kidney disease (CKD), but most emphasis is placed on adults rather than children. We examined yield of screening for CKD and hypertension among poor children in Mexico. On WKD (2006, 2007), children (age < 18 years) without known CKD were invited to participate at two screening stations. We measured body mass index (BMI), blood pressure, and serum creatinine, and performed dipstick urinalysis. The Schwartz equation was used to estimate glomerular filtration rate (GFR; reduced GFR defined as < 60 ml/min per 1.73 m(2)). Proteinuria and hematuria were defined by a reading of >or= 1+ protein or blood on dipstick. Hypertension was defined by gender, age, and height-specific norms. In total, 240 children were screened (mean age 8.9 +/- 4.1 years; 44.2% male). Proteinuria and hematuria were detected in 38 (16.1%) and 41 (17.5%), respectively; 15% had BMI > 95th percentile for age. Reduced GFR was detected in four (1.7%) individuals. Systolic hypertension was more prevalent in younger children (age 0-8 years, 19.6%; age 9-13 years, 7.1%; age 14-17 years, 5.3%) suggesting a possible white-coat effect. Hematuria, proteinuria, hypertension and obesity were frequently detected among children in a community based screening program in Mexico. This form of screening might be useful in identifying children with CKD and hypertension in developing nations.

Salt intakes around the world: implications for public health

BACKGROUND

High levels of dietary sodium (consumed as common salt, sodium chloride) are associated with raised blood pressure and adverse cardiovascular health. Despite this, public health efforts to reduce sodium consumption remain limited to a few countries. Comprehensive, contemporaneous sodium intake data from around the world are needed to inform national/international public health initiatives to reduce sodium consumption.

METHODS

Use of standardized 24-h sodium excretion estimates for adults from the international INTERSALT (1985-87) and INTERMAP (1996-99) studies, and recent dietary and urinary sodium data from observational or interventional studies--identified by a comprehensive search of peer-reviewed and 'grey' literature--presented separately for adults and children. Review of methods for the estimation of sodium intake/excretion. Main food sources of sodium are presented for several Asian, European and Northern American countries, including previously unpublished INTERMAP data.

RESULTS

Sodium intakes around the world are well in excess of physiological need (i.e. 10-20 mmol/day). Most adult populations have mean sodium intakes >100 mmol/day, and for many (particularly the Asian countries) mean intakes are >200 mmol/day. Possible exceptions include estimates from Cameroon, Ghana, Samoa, Spain, Taiwan, Tanzania, Uganda and Venezuela, though methodologies were sub-optimal and samples were not nationally representative. Sodium intakes were commonly >100 mmol/day in children over 5 years old, and increased with age. In European and Northern American countries, sodium intake is dominated by sodium added in manufactured foods ( approximately 75% of intake). Cereals and baked goods were the single largest contributor to dietary sodium intake in UK and US adults. In Japan and China, salt added at home (in cooking and at the table) and soy sauce were the largest sources.

CONCLUSIONS

Unfavourably high sodium intakes remain prevalent around the world. Sources of dietary sodium vary largely worldwide. If policies for salt reduction at the population level are to be effective, policy development and implementation needs to target the main source of dietary sodium in the various populations.

Frequency of diarrhoea as a predictor of elevated blood pressure in children

BACKGROUND

Diarrhoeal illness is a major public health problem for children worldwide, particularly among developing countries, and is a proxy condition for severe dehydration. It has been hypothesized that severe dehydration in the first 6 months of life could be associated with increased blood pressure later in life. This study aimed to explore whether frequency of diarrhoea is associated with elevated blood pressure in children in a setting with a high incidence of diarrhoeal disease.

METHODS

The present study is a cross-sectional study of blood pressure among children from a longitudinal child diarrhoeal disease cohort in Lima, Peru. From 2001 to 2006, daily diarrhoeal surveillance was made. Children were revisited in 2006 and blood pressure was measured. Diarrhoeal exposures were evaluated in terms of total number of diarrhoea days, number of episodes of diarrhoea, persistent diarrhoeal episodes and by the quartiles of daily incidence and episode incidence of diarrhoea.

RESULTS

The overall incidence of diarrhoeal episodes at age under 1 year was 4.35 (95% confidence interval: 3.79-4.98) and under 5 years was 2.80 (95% confidence interval: 2.69-2.92). No association was observed between the total number of diarrhoeal days, diarrhoeal episodes or diarrhoeal incidence rates with childhood blood pressure. There was weak evidence that hospital admission due to severe dehydration in the first year of life showed a gradient towards an increase in both, systolic and diastolic blood pressure.

CONCLUSION

In the first study to date to examine the association in a setting with a high incidence of diarrhoeal disease, diarrhoeal frequency did not show an association with increased blood pressure. Our observations of elevated levels of blood pressure among those admitted into hospitals in the first year of life are in line with the original hypothesis of dehydration in early infancy and high blood pressure. However, the effect of episodes of severe dehydration on later blood pressure remains uncertain.

Salt restriction in kidney disease--a missed therapeutic opportunity?

The importance of salt restriction in the treatment of patients with renal disease has remained highly controversial. In the following we marshal the current evidence that salt plays a definite role in the genesis of hypertension and target organ damage, point to practical problems of salt restriction, and report on novel pathomechanisms of how salt affects blood pressure and causes target organ damage.

A comprehensive review on salt and health and current experience of worldwide salt reduction programmes

Cardiovascular disease (CVD) is the leading cause of death and disability worldwide. Raised blood pressure (BP), cholesterol and smoking, are the major risk factors. Among these, raised BP is the most important cause, accounting for 62% of strokes and 49% of coronary heart disease. Importantly, the risk is throughout the range of BP, starting at systolic 115 mm Hg. There is strong evidence that our current consumption of salt is the major factor increasing BP and thereby CVD. Furthermore, a high salt diet may have direct harmful effects independent of its effect on BP, for example, increasing the risk of stroke, left ventricular hypertrophy and renal disease. Increasing evidence also suggests that salt intake is related to obesity through soft drink consumption, associated with renal stones and osteoporosis and is probably a major cause of stomach cancer. In most developed countries, a reduction in salt intake can be achieved by a gradual and sustained reduction in the amount of salt added to food by the food industry. In other countries where most of the salt consumed comes from salt added during cooking or from sauces, a public health campaign is needed to encourage consumers to use less salt. Several countries have already reduced salt intake, for example, Japan (1960-1970), Finland (1975 onwards) and now the United Kingdom. The challenge is to spread this out to all other countries. A modest reduction in population salt intake worldwide will result in a major improvement in public health.

Measuring dietary sodium intake in infancy: a review of available methods

It has been hypothesised that infancy may be a particularly sensitive period with respect to the effect of dietary sodium (salt) intake on later blood pressure. If this is the case, interventions to reduce dietary sodium intake in infancy could have major public health impact by reducing cardiovascular disease in the future. However, research in this area is hampered by difficulties of how to measure dietary sodium intake in infancy. Here we review the literature with an aim to describe different methods that have been used for research purposes, how these have been used and their relative strengths and limitations. We identified five studies that were relevant to our aim. In epidemiological and intervention studies sodium intake in infancy has been assessed via parents using diet diaries, which appear to be feasible and acceptable to parents. In these studies, sodium concentration in breast milk is assumed not to vary from one woman to the next, which may not be correct but has been poorly studied. The gold standard method - 24 h urinary excretion of sodium - was used in only one study and there is debate about the most appropriate way to collect urine for research purposes in infants. None of the studies directly compared different methods for determining infant dietary sodium intake. We conclude that research is required to determine the best methods of estimating dietary sodium intake in infants in different research contexts.

Dietary salt restriction and blood pressure in clinical trials

Dietary salt has long been recognized as a major factor affecting blood pressure such that sodium intake is a component of lifestyle modification guidelines for control of high blood pressure. These recommendations are based on results from epidemiologic observational studies and clinical trials of various sodium diets among normotensives and hypertensives. Nonetheless, results from the different studies vary such that specific recommendations regarding sodium intake are difficult to interpret. The results from several recent major trials indicated greater associations of blood pressure and sodium intake than earlier studies as well as meta-analyses of numerous clinical trials. The studies of sodium intake and blood pressures are complicated by measurements of intake, salt sensitivity, hypertension treatment, effects of sodium independent of blood pressure, and length of interventions. Limitations in the methodology of different studies have reduced the value of the results to provide specific and reliable sodium intake levels essential for clinical and lifestyle guidelines.

Complementary feeding: a commentary by the ESPGHAN Committee on Nutrition

This position paper on complementary feeding summarizes evidence for health effects of complementary foods. It focuses on healthy infants in Europe. After reviewing current knowledge and practices, we have formulated these conclusions: Exclusive or full breast-feeding for about 6 months is a desirable goal. Complementary feeding (ie, solid foods and liquids other than breast milk or infant formula and follow-on formula) should not be introduced before 17 weeks and not later than 26 weeks. There is no convincing scientific evidence that avoidance or delayed introduction of potentially allergenic foods, such as fish and eggs, reduces allergies, either in infants considered at increased risk for the development of allergy or in those not considered to be at increased risk. During the complementary feeding period, >90% of the iron requirements of a breast-fed infant must be met by complementary foods, which should provide sufficient bioavailable iron. Cow's milk is a poor source of iron and should not be used as the main drink before 12 months, although small volumes may be added to complementary foods. It is prudent to avoid both early (<4 months) and late (>or=7 months) introduction of gluten, and to introduce gluten gradually while the infant is still breast-fed, inasmuch as this may reduce the risk of celiac disease, type 1 diabetes mellitus, and wheat allergy. Infants and young children receiving a vegetarian diet should receive a sufficient amount ( approximately 500 mL) of breast milk or formula and dairy products. Infants and young children should not be fed a vegan diet.

Association of diarrhoea in childhood with blood pressure and coronary heart disease in older age: analyses of two UK cohort studies

BACKGROUND

There is a suggestion that acute dehydration in childhood may lead to elevated blood pressure. We examined if episodes of diarrhoea in childhood, a recognized proxy for acute dehydration, were related to measured blood pressure and coronary heart disease in older adults.

METHODS

Data were pooled from two prospective UK cohort studies (participants born 1920-39) in which episodes of diarrhoea were ascertained from health visitor records from birth until 5 years of age. Blood pressure and coronary heart disease were assessed during medical examination in men and women over 64 years of age. In total, 5203 men and women had data on diarrhoea in early life, adult blood pressure and a range of covariates; 4181 of these also had data on coronary heart disease status.

RESULTS

The prevalence of diarrhoea in infancy (3.3%) and between 1 and 5 years (1.1%) was low. There was no relation of diarrhoea from either period (age- and sex-adjusted results for diarrhoea in infancy presented here) with measured blood pressure [coefficient for systolic; 95% CI (confidence interval): 0.44; -2.88-3.76] or coronary heart disease (Odds ratio, OR; 95% CI: 0.91; 0.54-1.54) in adulthood. There was a similar lack of association when hypertension was the outcome of interest. These observations were unchanged after adjustment for a range of covariates.

CONCLUSIONS

In the largest study to date to examine the relation, there was no evidence that diarrhoea in early life had an influence on measured blood pressure, hypertension or coronary heart disease in older adults.

Nutrient intake in lysinuric protein intolerance

Lysinuric protein intolerance (LPI) is a rare autosomal recessive disorder characterized by defective transport of cationic amino acids. Poor intestinal absorption and increased renal loss of arginine, ornithine and lysine lead to low plasma concentrations of these amino acids and, subsequently, to impaired urea cycle function. The patients therefore have decreased nitrogen tolerance, which may lead to hyperammonaemia after ingestion of normal amounts of dietary protein. As a protective mechanism, most patients develop strong aversion to protein-rich foods early in life. Oral supplementation with citrulline, which is absorbed normally and metabolized to arginine and ornithine, improves protein tolerance to some extent, as do sodium benzoate and sodium phenylbutyrate also used by some patients. Despite effective prevention of hyperammonaemia, the patients still consume a very restricted diet, which may be deficient in energy, essential amino acids and some vitamins and minerals. To investigate the potential nutritional problems of patients with lysinuric protein intolerance, 77 three- to four-day food records of 28 Finnish LPI patients aged 1.5-61 years were analysed. The data suggest that the patients are clearly at risk for many nutritional deficiencies, which may contribute to their symptoms. Their diet is highly deficient in calcium, vitamin D, iron and zinc. Individualized nutritional supplementation accompanied by regular monitoring of dietary intake is therefore an essential part of the treatment of LPI.

Salt, the kidneys, and arterial hypertension

The kidneys play a major role in the regulation of the salt balance and thereby regulate blood pressure. Salt sensitivity is acquired or genetically-induced and is noted in about 50% of patients with essential hypertension. This property leads to a high cardiovascular risk. In this situation, the benefit of salt restriction is significant, and this dietary change should be associated with a high potassium intake. In patients treated by antihypertensive drugs, salt restriction improves the blood pressure control, which can permit a reduction of the number of drugs required to achieve a normal blood pressure. The recommended maximal salt intake should not exceed 6 grams/day (NaCl). Because most dietary salt comes from processed foods, the help of the food industry is crucial for a long-term compliance with a reduced salt intake, which could yield an additional important benefit in the reduction of cardiovascular risk.

Sodium intake in infancy and blood pressure at 7 years: findings from the Avon Longitudinal Study of Parents and Children

BACKGROUND

Infancy may be a sensitive period regarding effects of sodium intake on future blood pressure (BP). This has only been demonstrated in one randomized trial of low sodium formulae with follow-up in adolescence in one-third of participants.

OBJECTIVE

To prospectively assess associations between sodium intake in infancy and BP at 7 years in the Avon Longitudinal Study of Parents and Children (ALSPAC).

SUBJECTS

A total of 533 children with sodium data at 4 months and 710 children with sodium at 8 months.

RESULTS

0.4% of participants at 4 months and 73.0% at 8 months exceeded recommended levels for infant sodium intake. After minimal adjustment (child age, sex, energy), sodium intake at 4 months was positively associated with systolic blood pressure (SBP) at 7 years (beta=0.54 mm Hg/mmol; 95% CI: 0.09, 0.98 mm Hg; P=0.02). This changed little following adjustment for confounders but attenuated after adjusting for breastfeeding. This association was not mediated by sodium intake at 7 years. Due to high sodium-potassium correlations, effects of sodium independent of potassium could not be estimated with reasonable precision. Sodium intake neither at 8 months nor at 7 years was associated with SBP at 7 years.

CONCLUSION

The association between sodium intake at 4 months and future SBP requires replication in studies that can control for effects of potassium before we can conclude that early infancy is a sensitive period with respect to effects of sodium on future BP. The majority of infants exceeded recommended levels of sodium intake at 8 months, and interventions to reduce sodium in infants' diets should be considered.

Trends in body mass index, blood pressure and parental smoking habits in middle socio-economic level Turkish adolescents

Patterns of cardiovascular risk factors in populations are not static over time. We examined trends in body mass index (BMI), parental smoking and blood pressure over a 15-year period in Turkish children aged 15-17 years. Two cross-sectional studies were performed in secondary schools in Turkey in 1989-1990 and 2004-2005. Study participants were 673 children in 1989-1990 and 640 adolescents in 2004-2005. Main outcome measures were weight, height, BMI, presence and amount of parental smoking, systolic and diastolic blood pressure. Age and sex matched comparisons were performed to assess temporal trends in these measures. Children in 2004-2005 had increased weight, height, BMI and decreased systolic and diastolic blood pressure in all age groups compared with children in 1989-1990. According to the international criteria, 3.4% of children were obese and 15.8% were overweight in 2005, compared to 0.7% obese and 4.2% overweight in 1990 (P<0.001). However, a decrease was noted in blood pressure; 16% were classified as hypertensive in 1989-1990 versus 8% in 2004-2005 (P<0.001). The prevalence and amount of parental smoking also decreased over the last 15 years. We observed significant changes in BMI and blood pressure in Turkish children over the last 15 years. Temporal trends in these parameters may indicate a change in the pattern of cardiovascular disease in this population.

Long term effects of dietary sodium reduction on cardiovascular disease outcomes: observational follow-up of the trials of hypertension prevention (TOHP)

OBJECTIVE

To examine the effects of reduction in dietary sodium intake on cardiovascular events using data from two completed randomised trials, TOHP I and TOHP II.

DESIGN

Long term follow-up assessed 10-15 years after the original trial.

SETTING

10 clinic sites in 1987-90 (TOHP I) and nine sites in 1990-5 (TOHP II). Central follow-up conducted by post and phone.

PARTICIPANTS

Adults aged 30-54 years with prehypertension.

INTERVENTION

Dietary sodium reduction, including comprehensive education and counselling on reducing intake, for 18 months (TOHP I) or 36-48 months (TOHP II).

MAIN OUTCOME MEASURE

Cardiovascular disease (myocardial infarction, stroke, coronary revascularisation, or cardiovascular death).

RESULTS

744 participants in TOHP I and 2382 in TOHP II were randomised to a sodium reduction intervention or control. Net sodium reductions in the intervention groups were 44 mmol/24 h and 33 mmol/24 h, respectively. Vital status was obtained for all participants and follow-up information on morbidity was obtained from 2415 (77%), with 200 reporting a cardiovascular event. Risk of a cardiovascular event was 25% lower among those in the intervention group (relative risk 0.75, 95% confidence interval 0.57 to 0.99, P=0.04), adjusted for trial, clinic, age, race, and sex, and 30% lower after further adjustment for baseline sodium excretion and weight (0.70, 0.53 to 0.94), with similar results in each trial. In secondary analyses, 67 participants died (0.80, 0.51 to 1.26, P=0.34).

CONCLUSION

Sodium reduction, previously shown to lower blood pressure, may also reduce long term risk of cardiovascular events.

Functional effects of food: what do we know in children?

The knowledge base underpinning the setting of nutrient requirements for children and adolescents is not very secure. The advent of the concepts of optimal nutrition and functional foods has encouraged the possible use of functional effects as criteria for adequate nutrition in this age group. Target functions have been identified for growth development and differentiation and for behavioural and cognitive development. However, ideal markers or effects for these are not generally available. Additionally, nutrition in young people should avoid predisposing them to diet-related disease in later life. It is suggested that functional effects should include markers of reduction of risks of disease (nutritional safety) as well of benefits for health and well-being. Such markers of functional effects should be expected to arise from fundamental studies of nutrient–gene interactions and post-genomic metabolism.

Has blood pressure increased in children in response to the obesity epidemic?

The associations between elevated blood pressure and overweight, on one hand, and the increasing prevalence over time of pediatric overweight, on the other hand, suggest that the prevalence of elevated blood pressure could have increased in children over the last few decades. In this article we review the epidemiologic evidence available on the prevalence of elevated blood pressure in children and trends over time. On the basis of the few large population-based surveys available, the prevalence of elevated blood pressure is fairly high in several populations, whereas there is little direct evidence that blood pressure has increased during the past few decades despite the concomitant epidemic of pediatric overweight. However, a definite conclusion cannot be drawn yet because of the paucity of epidemiologic studies that have assessed blood pressure trends in the same populations and the lack of standardized methods used for the measurement of blood pressure and the definition of elevated blood pressure in children. Additional studies should examine if favorable secular trends in other determinants of blood pressure (eg, dietary factors, birth weight, etc) may have attenuated the apparently limited impact of the epidemic of overweight on blood pressure in children.

Diet, nutrition and the prevention of hypertension and cardiovascular diseases

Cardiovascular diseases (CVD) are growing contributors to global disease burdens, with epidemics of CVD advancing across many regions of the world which are experiencing a rapid health transition. Diet and nutrition have been extensively investigated as risk factors for major cardiovascular diseases like coronary heart disease (CHD) and stroke and are also linked to other cardiovascular risk factors like diabetes, high blood pressure and obesity. The interpretation of evidence needs to involve a critical appraisal of methodological issues related to measurement of exposures, nature of outcome variables, types of research design and careful separation of cause, consequence and confounding as the basis for observed associations.

Adequate evidence is available, from studies conducted within and across populations, to link several nutrients, minerals, food groups and dietary patterns with an increased or decreased risk of CVD. Dietary fats associated with an increased risk of CHD include trans–fats and saturated fats, while polyunsaturated fats are known to be protective. Dietary sodium is associated with elevation of blood pressure, while dietary potassium lowers the risk of hypertension and stroke. Regular frequent intake of fruits and vegetables is protective against hypertension, CHD and stroke. Composite diets (such as DASH diets, Mediterranean diet, ‘prudent’ diet) have been demonstrated to reduce the risk of hypertension and CHD. Sufficient knowledge exists to recommend nutritional interventions, at both population and individual levels, to reduce cardiovascular risk. That knowledge should now be translated into policies which promote healthy diets and discourage unhealthy diets. This requires coordinated action at the level of governments, international organizations, civil society and responsible sections of the food industry.

Nonpharmacologic therapy for hypertension: Does it really work?

Nondrug therapy of hypertension really does work but requires strong motivation by both patient and physician. In addition to global health benefits, prescription of weight loss, exercise, moderation of salt and alcohol intake, Dietary Approach to Stop Hypertension (DASH) eating plan, and tobacco avoidance can decrease the risk for normotensive and prehypertensive patients of developing fixed hypertension. Initiating and maintaining a healthy lifestyle may be sufficient to avoid pharmacologic therapy for some patients and is a valuable adjunct to drug therapy for most. Blood pressure lowering can be achieved by weight reduction (5-20 mm Hg/10 kg), DASH eating plan (8-14 mm Hg), dietary sodium reduction (2-8 mm Hg), increased physical activity (4-9 mm Hg), and moderation of alcohol consumption (2-4 mm Hg). Combination of two or more modalities may have an additive benefit. Cessation of tobacco abuse not only has global health benefits, but may reduce blood pressure.

Salt--a potential 'uremic toxin'?

It has been known for decades that salt (NaCl) determines extracellular volume as well as blood pressure and is one cause of hypertension. The difficulty to control the NaCl balance and thus treat sodium overload and hypertension in patients on dialysis has been recognized by Scribner in the early days of dialysis. In recent years, an impressive body of evidence has accumulated indicating that in essential hypertension, NaCl--blood pressure independently--causes target organ damage such as left ventricular hypertrophy, microalbuminuria, and increased aortic stiffness. It has further been recognized that NaCl increases oxidative stress and, again blood pressure independently, amplifies tissue injury induced by aldosterone. In renal damage models, progression is dramatically accelerated by high NaCl intake. Sodium as a potential culprit in progression to target organ damage in terminal renal failure has not been well investigated so far. However, it is possible, and indeed likely, that sodium plays an adverse role in the genesis of target organ damage in terminal renal failure.

Is systemic hypertension only a sign of chronic sodium chloride intoxication?

The most important obstacle for preventing hypertension is the belief that systemic hypertension has no identifiable cause. This belief, hiding the main offender, sodium chloride, causes too much time wasting for combating against hypertension. Accepting that sodium chloride is a drug and re-evaluating the situation at the light of current pharmacologic rules, it can be possible to get rid of the suspicions about the etiologic role of sodium chloride for developing systemic hypertension. It is apparent that systemic hypertension is a chronic intoxication produced by a drug (sodium chloride) whose dose is between minimal and maximal effective dose. Based on epidemiologic studies, minimal effective dose of salt, producing hypertension is estimated as 1.76 g/d. This suggests that the aim in this context should be removal of table salt from the human diet. Re-evaluating salt-hypertension relation by means of dose-response relation suggests that "salt sensitivity" is a baseless notion, because when the dose is between minimal and maximal effective dose, there are a number of individuals which respond up or down of any selected level, similar to other drugs. Another standpoint of refuting removal of salt is the belief that saltless diet is not palatable. According to the self-experiences of the Author, this belief is valid only for some time (for a few months), even a few years later saltless meals were perceived more palatable. The present paper describes evidences showing that systemic hypertension is formed by the chronic exposure to salt and it also answers contrary opinions.

Salt and Blood Pressure: Time to Challenge

Hypertension is a worldwide epidemic and its control is costly, but still inadequate. The mechanisms underlying the development of primary hypertension remain elusive. Several observations point to the kidney as a primary actor and sodium as the main culprit for development of hypertension. Over the last few decades, experimental, observational and clinical data have continuously indicated that excess salt intake is positively associated with elevated blood pressure and that blood pressure can be significantly reduced with substantial reductions in dietary sodium. This review highlights the pathophysiological mechanisms linking sodium to elevated blood pressure, synthesizes available evidence for the effect of reducing salt intake in controlling blood pressure. It specifically analyzes 6 recent meta-analyses and dietary approaches to stop hypertension.

Salty taste acceptance by infants and young children is related to birth weight: longitudinal analysis of infants within the normal birth weight range

BACKGROUND

Birth weight and sodium intake are both associated with risk for hypertension. It is not known whether birth weight influences response to salty taste.

OBJECTIVE

To assess the relationship between birth weight and salty taste acceptance of infants and young children.

DESIGN

Acceptance of salty taste was assessed at 2 (n = 80) and 6 (n = 76) months in infants (birth weight >2.5 kg) enrolled in a prospective cohort study. Acceptance was expressed as proportional intake following 1-min ingestion tests with water and salt solutions (0.17 and 0.34 mol/l NaCl, in water). Birth weight was obtained by maternal report. Questionnaires completed by mothers and food-ranking procedures performed by children evaluated salt liking and preference in a subset (n = 38) of subjects at preschool age (36 or 48 months).

SETTING

Nonprofit basic research institute in Philadelphia, PA, USA.

RESULTS

Regression analysis revealed significant negative associations between birth weight and acceptance of salty taste at 2 months (0.17 mol/l, P < 0.0001; 0.34 mol/l, P < 0.01) but not at 6 months. Relationships were not affected by adjustment for potential confounders. In preschoolers, greater liking of (P < 0.05) and preference for (P < 0.01) salty foods was associated with lower birth weight in simple, but not adjusted, models.

CONCLUSION

Measures related to salty taste preference were inversely related to birth weight over the first 4 years of life. Additional studies should substantiate these findings and explore whether early response to salty taste predicts future sodium intake, blood pressure, or other public health-related outcomes.

SPONSORSHIP

National Institutes of Health (DC 00882).

Diet and blood pressure in children

PURPOSE OF REVIEW

The prevalence of hypertension among children in the US is increasing in concert with rising obesity rates. Leading health organizations agree that elevated blood pressure should be managed in children; however, data on the relation between diet and lifestyle and blood pressure in this age group are sparse and controversial. The purpose of this review is to summarize the current evidence regarding nutrients, foods, and dietary patterns and their role in blood pressure elevation and in the treatment of pediatric hypertension.

RECENT FINDINGS

There is clear evidence that avoidance of excess weight gain in early life is important for the prevention of future hypertension and that weight reduction is an important therapeutic intervention for the prevention and treatment of hypertension in overweight children. Similarly, reduction in dietary sodium may be beneficial for children who are salt sensitive, but this trait cannot be easily measured. Children who were breast-fed or consume a diet rich in fruits, vegetables, and dairy foods tend to have lower blood pressure in adolescence. How these foods lower blood pressure is unclear.

SUMMARY

Data supporting the efficacy of dietary interventions for preventing or treating high blood pressure are limited. Future studies should emphasize adequate sample size, adjustment for confounding factors, use of standardized blood pressure techniques, and random assignment of children in intervention trials. Additionally, because adherence to dietary interventions may be particularly problematic among children, innovative nutrition intervention approaches are needed that address the unique needs and circumstances of this age group.

Blood pressure among very low birth weight (<1.5 kg) young adults

Our objective was to compare the blood pressure of 20-y-old very low birth weight (VLBW; <1.5 kg) individuals with that of normal birth weight (NBW) control individuals. The population included 195 VLBW (92 female and 103 male) and 208 NBW (107 female and 101 male) individuals who were born between 1977 and 1979. Independent effects of birth weight status (VLBW versus NBW) and within the VLBW cohort of intrauterine growth (birth weight z score) were examined via multiple regression analyses. VLBW individuals had a higher mean systolic blood pressure (SBP) than NBW control individuals (114 +/- 11 versus 112 +/- 13 mm Hg). SBP for VLBW female infants was 110 +/- 9 versus NBW 107 +/- 12 and for VLBW male individuals was 118 +/- 11 versus NBW 117 +/- 11 mm Hg. After adjustment for gender, race, and maternal education, the difference in SBP between VLBW and NBW individuals was 1.9 mm Hg but was 3.5 mm after also adjustment for later size (20-y weight and height z scores), which reflects catch-up growth. For female individuals, the difference in SBP between VLBW and NBW individuals was significant both unadjusted and adjusted for later size, whereas for male individuals, the difference was significant only after adjustment for later size. Intrauterine growth did not have a significant effect on SBP within the VLBW group, even after adjustment for later size. VLBW individuals, specifically female individuals, have a higher SBP than NBW control individuals. This is not explained by intrauterine growth failure.

Developmental determinants of blood pressure in adults

Over the past 20 years a large and varied body of research has attempted to make the case for the developmental origins of elevated adult blood pressure (BP). Experimental animal research has identified plausible biological mechanisms through which fetal nutritional insufficiency may affect adult BP. The majority of human epidemiologic studies demonstrate an inverse association of birth weight (the most commonly used marker of fetal nutrition) with adult BP and higher risk of hypertension among individuals with lower weight at birth. The most adverse BP outcomes occur among individuals who were small at birth but relatively large as adults, a finding that suggests a role for postnatal growth. We critically review the literature on proposed mechanisms and epidemiologic evidence for developmental origins of adult BP and hypertension, considering associations with birth weight, maternal nutrition during pregnancy, child growth patterns, and infant feeding.

Safety assessment and risk–benefit analysis of the use of azodicarbonamide in baby food jar closure technology: Putting trace levels of semicarbazide exposure into perspective – A review

The discovery of trace levels of semicarbazide (SEM) in bottled foods (especially baby foods) led to a consideration of the safety of this hydrazine compound by regulatory agencies worldwide. Azodicarbonamide, which is used in the jar-sealing technology known as Press On-Twist Off (or Push-Twist/PT) closures for the formation of a hermetic, plastisol seal, partially degrades with the heat of processing to form trace amounts of SEM. This review has evaluated the potential toxicological risks of resulting exposure to SEM and also the benefit of the PT technology (with azodicarbonamide) in the context of possible microbial contamination. It also considers the potential impact on infant nutrition if parents come to the conclusion that commercial baby foods are unsafe. SEM shows limited genotoxicity in vitro that is largely prevented by the presence of mammalian metabolic enzymes. Negative results were found in vivo in DNA alkaline elution, unscheduled DNA synthesis and micronucleus assays. This pattern is in contrast to the genotoxic hydrazines that also have been shown to cause tumours. Carcinogenicity studies of SEM are of limited quality, show a questionable weak effect in mice at high doses, which are not relevant to human exposure at trace levels, and show no effect in the rat. The IARC has assigned SEM as Group 3, 'Not classifiable as to its carcinogenicity to humans'. Based on estimates of exposure to infants consuming baby foods (with the assumption of SEM levels at the 95th percentile of 20 ng g(-1) in all of the consumed 'ready-to-eat' foods) compared with a no observed adverse effect level (NOAEL) in developmental toxicity studies, the margin of safety is more than 21 000. Since the risk of an adverse effect is negligible, it is clear that any theoretical risk is outweighed by the benefits of continuing use of the PT closure (with azodicarbonamide blowing agent) to ensure both the microbial integrity and availability of commercial baby foods as a valuable source of infant nutrition.

Infant feeding and components of the metabolic syndrome: findings from the European Youth Heart Study

AIMS

To assess the associations of type and duration of infant feeding with components of the metabolic syndrome in children aged 9 and 15.

METHODS

A total of 2192 randomly selected schoolchildren aged 9 and 15 years from Estonia (n = 1174) and Denmark (n = 1018) were studied. Insulin resistance (homoeostasis model assessment), triglyceride levels, high density lipoprotein cholesterol, and systolic blood pressure were measured.

RESULTS

Children who had ever been exclusively breast fed had lower systolic blood pressures than those who were not. With full adjustment for age, sex, country, birth weight, pubertal stage, body mass index, height, maternal and paternal education, income, smoking, and body mass index the mean systolic blood pressure of children who had ever been breast fed was 1.7 mm Hg (95% CI -3.0 to -0.5) lower than those who had never been exclusively breast fed. There was a dose-response in this association with decreasing mean systolic blood pressure across categories from never exclusively breast fed to breast fed for more than six months. Exclusive breast feeding was not associated with other components of the metabolic syndrome. Results were similar when examined separately in each country.

CONCLUSIONS

The magnitude of the association, its independence of important confounding factors, and the dose-response suggest that exclusive breast feeding is causally associated with reduced systolic blood pressure. The magnitude of the effect we found with blood pressure is comparable to the published effects of salt restriction and physical activity on blood pressure in adult populations, suggesting that it is of public health importance.

A life course approach to chronic disease epidemiology

A life course approach to chronic disease epidemiology uses a multidisciplinary framework to understand the importance of time and timing in associations between exposures and outcomes at the individual and population levels. Such an approach to chronic diseases is enriched by specification of the particular way that time and timing in relation to physical growth, reproduction, infection, social mobility, and behavioral transitions, etc., influence various adult chronic diseases in different ways, and more ambitiously, by how these temporal processes are interconnected and manifested in population-level disease trends. In this review, we discuss some historical background to life course epidemiology and theoretical models of life course processes, and we review some of the empirical evidence linking life course processes to coronary heart disease, hemorrhagic stroke, type II diabetes, breast cancer, and chronic obstructive pulmonary disease. We also underscore that a life course approach offers a way to conceptualize how underlying socio-environmental determinants of health, experienced at different life course stages, can differentially influence the development of chronic diseases, as mediated through proximal specific biological processes.

Early life determinants of adult blood pressure

PURPOSE OF REVIEW

While treating high blood pressure in middle age is beneficial in terms of reducing the occurrence of cardiovascular disease, treated and well controlled hypertensive adults still have a substantial excess mortality and reduced survival compared with normotensives. Therefore, identification of the means of preventing hypertension in earlier life is an important objective. There is increasing evidence that adult blood pressure is determined by a range of characteristics from the intrauterine period, through infancy and childhood. The purpose of this review is to provide a summary of the current evidence concerning the early life determinants of adult blood pressure.

RECENT FINDINGS

Children from poorer socioeconomic positions, those whose mothers experience pregnancy-induced hypertension, those whose mothers smoke throughout pregnancy, those with low birthweight, who are not breast-fed, who have high sodium diets in infancy and who are obese in childhood or adolescence tend to have higher blood pressure in adulthood. However, the mechanisms linking these early life factors to later blood pressure and the most appropriate means of preventing adult hypertension by intervening in early life are unclear.

SUMMARY

There is clear evidence that early life factors are important determinants of adult blood pressure. However, there is a need for randomized trials with sufficient resources for long-term follow-up to assess the effects that interventions such as preventing pregnancy-induced hypertension, reducing maternal smoking, increasing breast-feeding, reducing salt consumption in infancy and preventing childhood obesity have on adult blood pressure and cardiovascular disease.

Links between dietary salt intake, renal salt handling, blood pressure, and cardiovascular diseases

Epidemiological, migration, intervention, and genetic studies in humans and animals provide very strong evidence of a causal link between high salt intake and high blood pressure. The mechanisms by which dietary salt increases arterial pressure are not fully understood, but they seem related to the inability of the kidneys to excrete large amounts of salt. From an evolutionary viewpoint, the human species is adapted to ingest and excrete <1 g of salt per day, at least 10 times less than the average values currently observed in industrialized and urbanized countries. Independent of the rise in blood pressure, dietary salt also increases cardiac left ventricular mass, arterial thickness and stiffness, the incidence of strokes, and the severity of cardiac failure. Thus chronic exposure to a high-salt diet appears to be a major factor involved in the frequent occurrence of hypertension and cardiovascular diseases in human populations.