Inadequate supplies of potassium and magnesium in relief food--implications and countermeasures

Choice of foods and ingredients for moderately malnourished children 6 months to 5 years of age

There is consensus on how to treat severe malnutrition, but there is no agreement on the most cost-effective way to treat infants and young children with moderate malnutrition who consume cereal-dominated diets. The aim of this review is to give an overview of the nutritional qualities of relevant foods and ingredients in relation to the nutritional needs of children with moderate malnutrition and to identify research needs. The following general aspects are covered: energy density, macronutrient content and quality, minerals and vitamins, bioactive substances, antinutritional factors, and food processing. The nutritional values of the main food groups--cereals, legumes, pulses, roots, vegetables, fruits, and animal foods--are discussed. The special beneficial qualities of animal-source foods, which contain high levels of minerals important for growth, high-quality protein, and no antinutrients or fibers, are emphasized. In cereal-dominated diets, the plant foods should be processed to reduce the contents of antinutrients and fibers. Provision of a high fat content to increase energy density is emphasized; however, the content of micronutrients should also be increased to maintain nutrient density. The source of fat should be selected to supply optimal amounts of polyunsaturated fatty acids (PUFAs), especially n-3 fatty acids. Among multiple research needs, the following are highlighted: to identify the minimum quantity of animal foods needed to support acceptable child growth and development, to examine the nutritional gains of reducing contents of antinutrients and fibers in cereal- and legume-based diets, and to examine the role of fat quality, especially PUFA content and ratios, in children with moderate malnutrition.

Proposed Recommended Nutrient Densities for Moderately Malnourished Children

Recommended Nutrient Intakes (RNIs) are set for healthy individuals living in clean environments. There are no generally accepted RNIs for those with moderate malnutrition, wasting, and stunting, who live in poor environments. Two sets of recommendations are made for the dietary intake of 30 essential nutrients in children with moderate malnutrition who require accelerated growth to regain normality: first, for those moderately malnourished children who will receive specially formulated foods and diets; and second, for those who are to take mixtures of locally available foods over a longer term to treat or prevent moderate stunting and wasting. Because of the change in definition of severe malnutrition, much of the older literature is pertinent to the moderately wasted or stunted child. A factorial approach has been used in deriving the recommendations for both functional, protective nutrients (type I) and growth nutrients (type II).

A prospective assessment of food and nutrient intake in a population of Malawian children at risk for kwashiorkor

OBJECTIVE

To determine what foods, nutrients, and dietary patterns are associated with development of kwashiorkor in populations of vulnerable 1- to 3-year-old Malawian children.

PATIENTS AND METHODS

This was a prospective observational study conducted in 8 rural villages. Upon enrollment, demographic, anthropometric, and dietary intake data were collected. Children were studied every 2 weeks for 10 weeks to determine whether they developed kwashiorkor. Dietary intake was assessed on enrollment using a food frequency questionnaire, which included all possible foods in the child's diet. Food frequency data were used to estimate energy, protein, vitamins C and A, niacin, thiamin, zinc, and iron intake using food composition and serving size data. Dietary diversity was assessed with a 7-point score. Regression modeling was used to determine whether the consumption of any food or nutrient was associated with the development of kwashiorkor.

RESULTS

A total of 43 (2.6%) of the 1651 healthy children ages 1 to 3 years enrolled developed kwashiorkor. Children who developed kwashiorkor were younger and had more nutritional wasting than those who did not. Thirty children (70%) who developed kwashiorkor were breast-fed. In the combined regression model no foods or nutrients were found to be associated with the development of kwashiorkor. There were no differences in the dietary diversity between children who developed kwashiorkor and those who did not.

CONCLUSIONS

No association between the development of kwashiorkor and the consumption of any food or nutrient was found.

Public nutrition in complex emergencies

Public nutrition is a broad-based, problem-solving approach to addressing malnutrition in complex emergencies that combines analysis of nutritional risk and vulnerability with action-oriented strategies, including policies, programmes, and capacity development. This paper focuses on six broad areas: nutritional assessment, distribution of a general food ration, prevention and treatment of moderate malnutrition, treatment of severe malnutrition in children and adults, prevention and treatment of micronutrient deficiency diseases, and nutritional support for at-risk groups, including infants, pregnant and lactating women, elderly people, and people living with HIV. Learning and documenting good practice from previous emergencies, the promotion of good practice in current emergencies, and adherence to international standards and guidelines have contributed to establishing the field of public nutrition. However, many practical challenges reduce the effectiveness of nutritional interventions in complex emergencies, and important research and programmatic questions remain.

Dynamics and consequences of potassium shifts in skeletal muscle and heart during exercise

Since it became clear that K(+) shifts with exercise are extensive and can cause more than a doubling of the extracellular [K(+)] ([K(+)](s)) as reviewed here, it has been suggested that these shifts may cause fatigue through the effect on muscle excitability and action potentials (AP). The cause of the K(+) shifts is a transient or long-lasting mismatch between outward repolarizing K(+) currents and K(+) influx carried by the Na(+)-K(+) pump. Several factors modify the effect of raised [K(+)](s) during exercise on membrane potential (E(m)) and force production. 1) Membrane conductance to K(+) is variable and controlled by various K(+) channels. Low relative K(+) conductance will reduce the contribution of [K(+)](s) to the E(m). In addition, high Cl(-) conductance may stabilize the E(m) during brief periods of large K(+) shifts. 2) The Na(+)-K(+) pump contributes with a hyperpolarizing current. 3) Cell swelling accompanies muscle contractions especially in fast-twitch muscle, although little in the heart. This will contribute considerably to the lowering of intracellular [K(+)] ([K(+)](c)) and will attenuate the exercise-induced rise of intracellular [Na(+)] ([Na(+)](c)). 4) The rise of [Na(+)](c) is sufficient to activate the Na(+)-K(+) pump to completely compensate increased K(+) release in the heart, yet not in skeletal muscle. In skeletal muscle there is strong evidence for control of pump activity not only through hormones, but through a hitherto unidentified mechanism. 5) Ionic shifts within the skeletal muscle t tubules and in the heart in extracellular clefts may markedly affect excitation-contraction coupling. 6) Age and state of training together with nutritional state modify muscle K(+) content and the abundance of Na(+)-K(+) pumps. We conclude that despite modifying factors coming into play during muscle activity, the K(+) shifts with high-intensity exercise may contribute substantially to fatigue in skeletal muscle, whereas in the heart, except during ischemia, the K(+) balance is controlled much more effectively.