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The complexity and mystery of linear growth

Student Blogger for Global Nutrition Council at ASN’s Scientific Sessions and Annual Meeting at EB 2016

By: Sheela Sinharoy, MPH

A symposium called Biology of Linear Growth on Tuesday examined linear growth from the molecular to the population level, bringing perspectives from biology, physical anthropology, nutrition, and epidemiology

Are you familiar with the process of endochondral ossification? Julian Lui, MD PhD explained that this is the process that results in linear growth. It takes place in the growth plates, at the end of long bones such as the femur, and is subject to systemic regulation by endocrine, nutritional, and inflammatory cytokine factors as well as local regulation by paracrine factors and other cellular mechanisms. Malnourished children have lower levels of hormones like insulin-like growth factor 1 (IGF-1) and estrogen, as well as increased levels of glucocorticoids, leading to decreased linear growth. Dr. Liu explained that this allows the body to conserve resources and that, in situations of food insecurity, “Growth is something of a luxury that can be postponed until better times.”

Rather than growing continuously, children grow in saltations, meaning that – as many a parent has observed – a child may grow substantially overnight and then not at all for a number of days afterwards. Michelle Lampl, MD PhD stated that as children age, these saltations become less and less frequent, with older children growing much less often than infants. The amount and frequency of these growth saltations can be affected by environmental factors, which can interact with cellular effects. Maternal smoking, for example, has a well-documented inhibitory effect on growth, as does maternal alcohol consumption and stress.

Since linear growth happens most rapidly in early life, the first 1,000 days from conception to two years of age are considered a critical period. Parul Christian, DrPH presented results from a meta-analysis analyzing various maternal and child nutrition interventions targeting this 1,000-day window. Starting during pregnancy, balanced protein-energy, iron-folic acid, and multiple micronutrient supplementation were all found to increase birth weight. However, maternal supplementation during pregnancy was not associated with any long-term linear growth in children under five years old. For infants and young children, nutrition promotion and food supplementation showed promise as interventions with positive impacts on child height.

In the final talk of the symposium, Aryeh Stein, PhD addressed the question of linear catch-up growth: for those children whose growth has been suppressed by malnutrition, is it possible to catch up on missed growth, even after the first 1,000 days? A number of studies have provided different nutrients and foods to children ages two and older. Dr. Stein presented results from studies of protein, zinc, iron, iodine, calcium, multiple micronutrients, and food. Protein and some of the micronutrients may have promise, but several of the calcium studies reported negative effects, while food had no association with growth.

The symposium made it clear that nutrition has an important role to play in stimulating or inhibiting linear growth. However, a great deal remains to be learned about these complex biological processes and the most effective interventions to promote children’s optimal growth.

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Designing interventions to achieve impact

Student Blogger for Global Nutrition Council at ASN’s Scientific Sessions and Annual Meeting at EB 2016

By: Sheela Sinharoy, MPH

A symposium titled Program Effectiveness for Addressing Undernutrition during the First 1,000 Days provided attendees with examples of programs in Bangladesh, Guatemala, and Burundi.

In Bangladesh, the Rang-Din Nutrition Study tested lipid-based nutrient supplements (LNS) in a community-based program. According to presenter Kay Dewey, the study found that giving LNS to mothers prenatally reduced the prevalence of stunting and increased the birth weight, head circumference, and body mass index (BMI) in infants at birth. LNS and multiple micronutrient powders (MNP) for children were also associated with better developmental and cognitive outcomes. Dr. Dewey noted that the impact on child anthropometry was much larger in food insecure households, so future programs may want to target based on this and other criteria.

Moving from Asia to Africa, Marie Ruel presented results from an impact evaluation of a food-assisted integrated health and nutrition program in Burundi. The program gave food rations to mothers and children and also provided behavior change communication. Interestingly, the nutrition situation in Burundi deteriorated sharply during the program period, but decreases were less severe in the treatment groups. For example, while the prevalence of stunting increased dramatically in the control group, the prevalence in the treatment group remained essentially flat. Thus, although the treatment group did not improve, the results suggest that the intervention protected families who otherwise would have been vulnerable to economic shocks.

Guatemala is another country with a very high prevalence of chronic undernutrition, and Deanna Olney presented results from a study of a similar food assistance program. The impact of the program was greatest among those who received a full family food ration plus an individual ration of corn-soy blend. In these households, mothers had significantly higher mean BMIs, children had a lower prevalence of stunting, and both mothers and children had a lower prevalence of anemia. However, there were no significant impacts on child underweight, wasting, or language or motor development.

The differing impacts of various programs was the impetus for a talk by Per Ashorn, who discussed pathways of impact for fetal growth, linear growth, and cognitive function. He explained that the pathways for linear, ponderal, and head growth are partially different, and there are possibly partially different pathways to childhood length gain and brain function. This suggests a need for multipronged interventions targeting pathways including infection, nutrition, and inflammation, as well as a variety of outcome measures to assess the interventions’ impact.

Of course, cost is an important – and often challenging – issue when planning interventions. The final talk of the symposium was given by Steve Vosti, who explained that programs must balance need, acceptability, use, and both short-term and persistent demand in order to achieve impact. These and many other factors, such as the costs of manufacturing supplements in country and the proportion of locally available ingredients being used, can affect the cost of an intervention. In addition to deciding on the most appropriate intervention to meet a need, practitioners must take these factors into account when planning their programs.

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What Do Toilets Have to Do With Nutrition?

By Sheela Sinharoy

When people think of nutrition, they probably do not think immediately of toilets. However, there is growing interest within the global public health community in the relationship between sanitation and nutrition. A group of researchers led by Dr. Tom Clasen of Emory University and the London School of Hygiene and Tropical Medicine has been studying this topic. They recently published findings from a study examining the effectiveness of a rural sanitation program on several outcomes, including child malnutrition, in The Lancet.

The intervention took place in Odisha, India, in the context of the national Total Sanitation Campaign, through which the government of India promotes latrine construction. The campaign focuses on households below the poverty line; it provides them with a latrine but requires that they contribute materials and labor for construction. For this study, the researchers selected 100 rural villages and enrolled households with pregnant women or children under age four. The study took place between May 2010 and December 2013.

Malnutrition was measured in two ways, through height-for-age z-score (HAZ) in children under two and weight-for-age z-score (WAZ) in children under five. The intervention had no effect on mean HAZ. Intention-to-treat analysis also showed no effect on mean WAZ, but per-protocol analysis showed a modest effect size of 0.10 (95% CI: 0.003-0.20). In other words, among the households that were compliant with the intervention, the children had slightly better WAZ scores. The absence of a stronger effect was surprising enough to garner attention from The New York Times, which published an article titled, “Latrines May Not Improve Health of Poor Children.”

I wanted to learn more, so I spoke with Dr. Clasen about the findings. He explained that while latrine coverage increased through the intervention, latrine use remained sub-optimal. While it may seem counter-intuitive, many community members chose not to use their new latrines, preferring instead the culturally accepted practice of open defecation. In particular, the study found that “latrine use was nearly five times higher for women than for men or children.” The reasons behind these gender and age differences are not clear, but Dr. Clasen emphasized the need to increase latrine use, aiming for “everybody, all the time.”

Researchers are examining other potential factors influencing latrine compliance. For example, what role do women play in deciding whether a household invests the resources necessary to build a latrine? If this decision is in the hands of men, and men are less likely to use a latrine, what are the implications for sanitation coverage and compliance? The study team is carrying out analyses on these and many other questions.

Ultimately, Dr. Clasen explained, this was an isolated intervention that could not address the multitude of issues that might affect the study outcomes. Factors such as poor disposal of child feces, the close proximity of livestock, poor water quality, and other forms of contamination likely play an important role in determining child nutrition outcomes. As always, more research is needed to better understand the complicated relationship between sanitation and nutrition.

Reference
Clasen T, Boisson S, Routray P, Torondel B, Bell M, Cumming O, et al. Effectiveness of a rural sanitation programme on diarrhea, soil-transmitted helminth infection, and child malnutrition in Odisha, India: a cluster-randomised trial. Lancet. 2014 [cited 2014 Nov 3]. https://www.thelancet.com/journals/langlo/article/PIIS2214-109X%2814%2970307-9/abstract

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Changes on the Horizon: Redefining Malnutrition Diagnoses in Older Adults

By Jonelle Agurs, ASN Intern

No one wants to get half a diagnosis from their doctor.

Unfortunately, that’s what tends to happen when diagnosing malnutrition in hospitalized adult patients in the United States. The present criteria for some malnutrition assessments, like the Malnutrition Screening Tool (MST), are under scrutiny because they only evaluate patients on symptoms of starvation, such as unintentional weight loss or poor appetite. However, new studies postulate that malnutrition should not be limited to food behaviors, but should be expanded to include inflammation resulting from chronic disease. The body’s inflammatory response can intensify the symptoms of starvation, and vice versa; poor eating habits may induce inflammation as well. The human body does an impeccable job of patching itself up using the inflammatory response, but this process often triggers symptoms strongly associated with malnutrition, such as weight loss. With approximately half of the U.S. adult population (117 million) suffering from at least one chronic condition, such as coronary heart disease and diabetes, it is no surprise that there is an increasing prevalence of malnutrition cases among hospitalized adult patients.

ASN supports the efforts of many of its partner organizations, such as the American Society for Parenteral and Enteral Nutrition and the Academy of Nutrition and Dietetics, which want to recognize the role of the inflammatory response when diagnosing malnutrition. They have proposed four standard criteria: insufficient energy intake, unintended weight loss, muscle mass and fat loss, and diminished physical function. These criteria will support a more etiological-based diagnosis of malnutrition; a diagnosis more closely linked to the chronic diseases that cause it. Misdiagnoses often result in patients being discharged early from hospital care, causing inpatients to return later for health issues made worse by the symptoms of poor nutrition.

The International Classification of Diseases, 10th Revision, or ICD-10, is a coding system under the Affordable Care Act of 2010, scheduled to be implemented after October 1, 2015. Designed to improve disease management, this revision will include coding using an updated definition of malnutrition. Absence of a standard screening system for this condition is like installing the proverbial cork in the leaky faucet; diagnoses without a simple malnutrition assessment may “plug” up the issue, but the pressure continues to build, waiting for a more thorough solution. The expansion of the ICD-10 coding system will provide a part of that solution by enhancing screening accuracy. With five times more descriptors than its ICD-9 predecessor, ICD-10 coding will include more conditions that could be linked to a range of malnutrition-related issues.

Hospitals across the nation are preparing for the ICD-10 updates, but it is imperative that hospital personnel fully understand how to recognize and diagnose malnutrition to code it properly. Despite shortages of nursing staff and other trained individuals, quality of patient care must be maintained in order to indicate their risk of malnutrition. Clinicians must be able to perform comprehensive assessments of the patient’s complete medical background, so that, along with the newly-proposed diagnostic construct, every patient will receive comprehensive care that will, ideally, lower the cost of their medical care expenses in the future.

Malnutrition, among other hospital-based nutrition topics will be discussed on Saturday, December 6 during the fourth annual Advances and Controversies in Clinical Nutrition conference. Dr. Gordon Jensen, ASN’s immediate past president, will give an address titled “Malnutrition and the Affordable Care Act.” The conference runs December 4-6 at the Gaylord National Resort & Convention Center in National Harbor, MD, and features a dynamic program with topics ranging from dietary supplements to nutrition and cancer. To learn more about this year’s conference, please visit the website.

Reference
Jensen, G, Compher, C, Sullivan, D, Mullin, G. (2013). Recognizing Malnutrition in Adults: Definitions and Characteristics, Screening, Assessment, and Team Approach. Journal of Parenteral and Enteral Nutrition, 802-807.

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