Trends of serum phospholipid fatty acids over time in rural Uganda: evidence of nutritional transition?

Non-communicable diseases are projected to become the most common causes of death in Africa by 2030. The impact on health of epidemiological and nutritional transitions in sub-Saharan Africa remains unclear. To assess the trends of dietary fatty acids over time in Uganda, we examined fatty acids in serum collected from individuals in rural south-west Uganda, at three time points over two decades. Independent cross-sectional samples of 915 adults and children were selected from the general population cohort in 1990 (n 281), 2000 (n 283) and 2008 (n 351). Serum phospholipid fatty acids were measured by GC. Multivariate regression analyses were performed to compare the geometric means of fatty acids by time period. Serum fatty acid profiling showed high proportions of SFA, cis-MUFA and industrial trans-fatty acids (iTFA), likely to be biomarkers of high consumption of palm oil and hydrogenated fats. In contrast, proportions of n-6 and n-3 PUFA from vegetable oils and fish were low. From 1990 to 2008, serum phospholipids showed increases in absolute amounts of SFA (17·3 % increase in adults and 26·4 % in children), MUFA (16·7 % increase in adults and 16·8 % in children) and n-6:n-3 PUFA (40·1 % increase in adults and 39·8 % in children). The amount of elaidic acid, iTFA from hydrogenated fats, increased in children (60·1 % increase). In this rural Ugandan population, we show evidence of unfavourable trends over time of dietary fatty acids.

The hierarchical structure and mechanics of plant materials.

The cell walls in plants are made up of just four basic building blocks: cellulose (the main structural fibre of the plant kingdom) hemicellulose, lignin and pectin. Although the microstructure of plant cell walls varies in different types of plants, broadly speaking, cellulose fibres reinforce a matrix of hemicellulose and either pectin or lignin. The cellular structure of plants varies too, from the largely honeycomb-like cells of wood to the closed-cell, liquid-filled foam-like parenchyma cells of apples and potatoes and to composites of these two cellular structures, as in arborescent palm stems. The arrangement of the four basic building blocks in plant cell walls and the variations in cellular structure give rise to a remarkably wide range of mechanical properties: Young's modulus varies from 0.3 MPa in parenchyma to 30 GPa in the densest palm, while the compressive strength varies from 0.3 MPa in parenchyma to over 300 MPa in dense palm. The moduli and compressive strength of plant materials span this entire range. This study reviews the composition and microstructure of the cell wall as well as the cellular structure in three plant materials (wood, parenchyma and arborescent palm stems) to explain the wide range in mechanical properties in plants as well as their remarkable mechanical efficiency.