Impact of seasonal scarcity on energy balance and body composition in peasant adolescents from Calakmul, Campeche Mexico

Seasonal changes in body composition in children from Maya agriculturalists in central Yucatán, Mexico

INTRODUCTION

Development policies have aimed to substitute subsistence agriculture for cash crops or other cash generating activities to encourage local farmers to depend on store-bought groceries available year-round instead of seasonal subsistence crops. In this paper, we test the hypothesis that increased dependence on store bought foods has decreased seasonal changes in nutritional status and fat mass in Maya Children from Yucatan, Mexico.

METHODS

Weight for age (W/A), body mass index (BMI), and tricipital Skinfold z scores in children under the age of 10 years from 14 Maya rural towns with different degrees of development were compared longitudinally between scarcity and abundance seasons using a repeated measures analysis of variance. Height for age (H/A) z scores were also estimated.

RESULTS

Origin of food consumed corresponded to the town's degree of development. Nutritional status (W/Az) and adiposity, BMI, and tricipital z scores were significantly lower during the scarcity season in every community. W/Az, tricipital skinfold z, and H/Az scores were significantly higher in developed than in traditional towns, yet in both types of town W/Az and H/Az scores were below the WHO standard mean. Tricipital skinfold z score was only below the WHO standard amongst traditional towns during the scarcity season.

CONCLUSIONS

Increased dependence on store foods failed to eliminate significant losses in body fat during the scarcity season. This failure may be affecting linear growth and promoting a thrifty phenotype that is seen in short and stocky individuals with a tendency to accumulate fat during abundance seasons.

Hydrothermally-treated soybean-fortified maize-based nsima (stiff porridge) could contribute towards alleviating seasonal body weight loss in farming communities in sub-Saharan Africa

Objective

This study explored the use of hydrothermally-treated soybean-fortified maize-based stiff porridge (nsima) in managing body weight losses among the farming family community in Malawi during the labour-intensive cropping (growing) season. We hypothesized that soybean-fortified maize-based nsima could prevent seasonal body weight losses in farming communities during labour-intensive seasons better than conventional 100% maize nsima.

Research methods & procedures

A single-blind parallel dietary intervention 90-day study. During energy stress months, 42 farming households in Malawi were supplied with 15 kg of blind formulation of soybean-fortified maize flour (soybean: maize, 1:4, wt/wt) per person per month except for under-fives who were allotted half the quantity. Forty households were provided with equivalent quantities of 100% maize flour and served as control. Body weights of participants were taken at baseline and endpoint.

Results

After 3 months, the experimental group registered 3.7, 4.2, 2.9, and 5.2% statistically higher body weight compared to the controls for the under-five, the 5-9-year-olds, the 10-19-year-olds, and the >20-year-olds, respectively.

Conclusion

Soybean-fortified stiff porridge could feasibly be used to alleviate wasting among the resource-constraint populace in Malawi and many other parts of sub-Saharan Africa that rely on maize as a major staple.

Seasonal variability of the vitamin D effect on physical fitness in adolescents

Studies investigating the relationship between vitamin D and physical fitness in youth have provided inconsistent findings. Recent evidence indicates that the expression of receptors and vitamin D-modulated genes in young subjects has a seasonal profile. Therefore, we investigated the role of vitamin D on physical fitness across seasons in a total of 977 male adolescents. Anthropometrics, lifestyle, dietary habits, biochemical profiles and physical fitness were studied. Multiple linear regression models, including pairwise interaction terms involving total 25-OH-vitamin D, were fitted. The interacting effect of season and total 25-OH-vitamin D had a significant influence on physical fitness performance (spring and total 25-OH-vitamin D: ß 0.19, SE 0.07, p = 0.007; summer and total 25-OH-vitamin D: ß 0.10, SE 0.06, p = 0.11; autumn and total 25-OH-vitamin D: ß 0.18, SE 0.07, p = 0.01), whereas the main effect of total 25-OH-vitamin D alone was not significant (p = 0.30). Body fat percentage, recreational physical activity level, time spent per day gaming/TV-watching, smoking, and hemoglobin levels were also related to the physical fitness performance score. Future studies should further explore the role of seasonal-dependent effects of vitamin D on health.

Impact of commercial farming on household reproductive strategies in Calakmul, Campeche, Mexico

OBJECTIVES

The purpose of this study was to determine if commercial agriculture can lead to changes in peasant reproductive strategies in migrant agriculturalists from Calakmul, Campeche, Mexico.

METHODS

The reproductive histories of 746 women from Calakmul, Campeche, Mexico were collected. The sample was first divided into women who had reproduced within or outside of Calakmul (RC and RO, respectively) and these were further subdivided into those who lived in households practicing subsistence agriculture and those who turned agriculture into a business (Household Subsistence Agricultural Strategy (HSA) and Household Commercial Agricultural Strategy (HCA), respectively). Age-specific fertility rate (ASFR) differences were compared between strategies and place of reproduction. Comparisons between interbirth interval and age at which desired fertility was reached were done with a Kaplan-Meier life table-based statistic.

RESULTS

In both strategies, RC women increased ASFRs by reducing age at first birth, and HSA-RC women also reduced interbirth intervals. HCA women had lower ASFRs than HSA women. The latter had a natural fertility pattern while the former expressed a desire to stop reproducing at a younger age. HCA-RC women showed important fertility reductions after age 25 and HCA-RO women after age 30.

CONCLUSIONS

Fertility reductions in households that practice commercial versus those that practice subsistence agriculture were significant. Also, a "frontier" effect was observed that increased fertility over all, but HCA households were not as influenced by it.

Sexual relationship power and malnutrition among HIV-positive women in rural Uganda

Inequality within partner relationships is associated with HIV acquisition and gender violence, but little is known about more pervasive effects on women's health. We performed a cross-sectional analysis of associations between sexual relationship power and nutritional status among women in Uganda. Participants completed questionnaires and anthropometric measurements. We assessed sexual relationship power using the Sexual Relationship Power Scale (SRPS). We performed logistic regression to test for associations between sexual relationship power and poor nutritional status including body mass index, body fat percentage, and mid-upper arm circumference. Women with higher sexual relationship power scores had decreased odds of low body mass index (OR 0.29, p = 0.01), low body fat percentage (OR 0.54, p = 0.04), and low mid-upper arm circumference (OR 0.22, p = 0.01). These relationships persisted in multivariable models adjusted for potential confounders. Targeted interventions to improve intimate partner relationship equality should be explored to improve health status among women living with HIV in rural Africa.

Seasonal variations in physical activity and implications for human health

This review explores the implications of seasonal changes in physical activity for fitness and human health. Photosensitivity and nutrient shortages mediate animal hibernation via the hypothalamus and changes in leptin and ghrelin concentrations. Opportunities for hunting and crop cultivation determine seasonal activity in under-developed human societies, but in developed societies temperature and rainfall are dominant influences, usually over-riding innate rhythms. Both questionnaire data and objective measurements show that many groups from children to the elderly increase their physical activity from winter to spring or summer. Measurements of maximal oxygen intake and muscle strength commonly show parallel seasonal changes. However, potential effects upon body mass and body fat may be counteracted by changes of food intake; subsistence agriculturists sometimes maintain or increase physical activity at the expense of a decrease in body mass. In developed societies, body fat commonly increases during the winter, with parallel changes in blood lipids, blood pressure and blood coagulability; moreover, these changes are not always fully reversed the following summer. Most developed societies show increased all-cause and cardiac mortalities in the winter. Health consequences of seasonal variations in physical activity including an increased vulnerability to cardiac catastrophe and a year-by-year increase in total body fat seem most likely if the average level of physical activity for the year is low. Public health recommendations should underline the importance of maintaining physical activity during adverse environmental conditions by adapting clothing, modifying behaviour and exploiting any available air-conditioned indoor facilities.