The erythrocyte membrane disturbances in protein-energy malnutrition: nature and mechanisms

The possible role of essential fatty acids in the pathophysiology of malnutrition: a review

Biochemical evidence of essential fatty acid deficiency (EFAD) may exist in protein-energy malnutrition (PEM). EFAD is characterised by low 18:2omega6, often in combination with low 20:4omega6 and 22:6omega3, and high 18:1omega9 and 20:3omega9. Some PEM symptoms, notably skin changes, impaired resistance to infections, impaired growth rate and disturbed development may at least partly be explained by EFAD. One or more of the following factors could induce EFAD in PEM: low EFA intake, poor lipid digestion, absorption, transport, desaturation and increased EFA beta-oxidation and peroxidation. EFAD may perpetuate itself by decreasing lipid absorption and transport, and aggravate PEM by impairing nutrient absorption and dietary calorie utilisation. Micronutrient deficiencies may contribute to the impaired EFA bioavailability and metabolism. Nutritional rehabilitation strategies in PEM may consider adequate intakes of EFA and micronutrients, e.g. by promoting breastfeeding. More research is required to gain detailed insight into the role of EFAD in PEM.

Concentrations of riboflavin and related organic acids in children with protein-energy malnutrition

BACKGROUND

Riboflavin, flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD) concentrations have been little studied in cases of malnutrition.

OBJECTIVE

Our objective was to investigate the effects of malnutrition on riboflavin status and riboflavin's relation with thyroid hormones and concentrations of urinary organic acids.

DESIGN

Malnourished children from the savannah in Benin (group S, n = 30) and the coast in Togo (group C, n = 30), as well as 24 control subjects from both regions, were studied. Blood riboflavin, FMN, and FAD were analyzed by HPLC; urinary organic acids were analyzed by gas chromatography-mass spectrometry.

RESULTS

Children in group S were more severely malnourished than children in group C. Triiodothyronine concentrations were lower in group S than in group C or the control group (1.12 +/- 0.24 compared with 1.74 +/- 0.18 and 2.92 +/- 0.19 nmol/L, respectively; P < 0.0001). Plasma riboflavin concentrations in group S were higher than those in group C or the control group (66.90 +/- 12.75 compared with 28.09 +/- 9.12 and 20.08 +/- 3.03 nmol/L, respectively; P < 0.001). Plasma FAD concentrations in group S were lower than those in group C or the control group (31.57 +/- 10.19 compared with 59.02 +/- 5.60 and 65.35 +/- 5.23 nmol/L, respectively; P < 0.0001). Dicarboxylic aciduria was higher in group C than in group S or the control subjects.

CONCLUSIONS

Children in group S had low triiodothyronine concentrations and low conversion of plasma riboflavin into its cofactors, leading to a plasma FAD deficiency. Plasma FAD was not correlated with urinary dicarboxylic acid concentrations.

Depletion of delta 9 desaturase (EC 1.14.99.5) enzyme activity in growing rat during dietary protein restriction

The effects of protein restriction on delta 9 desaturase (EC 1.14.99.5) activity were studied in growing rats. A control group was fed on a balanced diet (200 g casein/kg; BD) for 28 d. The experimental group was fed on the low-protein diet (20 g casein/kg; LP) for 26 d, then refed the balanced diet (BD-R) for 2 d. Rats were born to and suckled from normally fed dams. The enzyme activity was measured after 2 and 14 d of LP, and 26 d of LP plus 2 d of BD-R, by incubations in vitro of hepatic microsomal pellets with [1-14C]steric acid. The results indicated a decreased delta 9 desaturase activity after 2 and 14 d of LP of -33 and -43% respectively. Refeeding for 2 d was sufficient to super-repair this activity (+66%). The fatty acid composition of total liver lipids and microsomal phosphatidylethanolamines (PE) and phosphatidylcholines (PC) were also investigated; 18:0 decreased in total liver lipids at 14 d of LP, when 18:1n-9 increased. Stearic acid (18:0) increased in PC at 2 d of LP and in PE at 14 d of LP; oleic acid (18:1n-9) did not change. Therefore, it is concluded that a defect occurred in the bioconversion of 18:0 into 18:1n-9 by delta 9 desaturation during protein depletion. As oleic acid is accumulated in total liver lipids during LP, we speculate that this is due to a decreased oxidation or transport of this fatty acid.

Fatty acid composition of erythrocyte membrane lipid obtained from children suffering from kwashiorkor and marasmus

The fatty acid composition of erythrocyte membrane (EM) lipids obtained from normal, kwashiorkor, and marasmic children was analyzed by gas chromatography. The proportion of palmitic acid (16:0) was lower and of oleic acid (18:1) higher in the kwashiorkor group than in the control group. The marasmic group showed lower proportions of eicosatrienoic acid (20:3) and arachidonic acid (20:4) and a higher proportion of oleic acid (18:1) than the control group. A significant difference was found between the marasmic and kwashiorkor groups with respect to arachidonic acid (20:4), which showed a lower proportion in the former group than the latter. The ratio of arachidonic acid to linoleic acid (20:4/18:2) was markedly lower in the marasmic group than the control group, suggesting a possible impairment in the conversion of linoleic acid to arachidonic acid in marasmic children. The ratio of unsaturated fatty acids to saturated fatty acids was markedly elevated in the kwashiorkor group over that of control group, indicating increased fluidity of EM in kwashiorkor. It is suggested that the altered membrane fatty acid composition reflects deranged lipid metabolism and affects the physical and physiological properties of EM and could contribute to changes in the activities of several red blood cell membrane-bound enzymes reported earlier in kwashiorkor children.

Fatty acid composition of plasma lipids in Nigerian children with protein-energy malnutrition

The fatty acid (FA) composition of the main plasma lipids was analysed in eight well-nourished, generally healthy Nigerian children aged 14.1 +/- 7.2 months and in 17 malnourished children (8 marasmus, 9 kwashiorkor) aged 14.6 +/- 3.8 months within the first 2 days of admission at the Dept. of Child Health, University of Benin. In comparison to the control group, the malnourished children showed a marked decrease of polyunsaturated FA with low linoleic acid, mainly in sterol esters (STE), and severely reduced linoleic acid metabolites, including arachidonic acid, in all lipid fractions. omega-3-FA were not altered except for a reduction of docosapentaenoic and docosahexaenoic acids in phospholipids. Clearly increased values were found for saturated FA in STE and for the non-essential monoenoic FA in all lipid classes. This pattern indicates the presence of essential fatty acid deficiency in the malnourished children. There was no significant difference between marasmus and kwashiorkor. Eight malnourished children were followed up in the early phase of recovery during hospital treatment 14.0 +/- 3.1 days after obtaining the first sample. Linoleic acid had increased again in STE, but its metabolites were as low or even lower than before. An impaired activity of delta-6-desaturase, the rate limiting enzyme of linoleic acid metabolism, in suggested by elevated substrate-product-ratios of this enzyme in untreated children with protein energy malnutrition and in the early phase of recovery, which may be due to low insulin levels, protein and zinc deficiency. The trientetraen ratio (20:3 omega 9/20:4 omega 6) thus is not a reliable indicator of essential FA status in protein-energy malnutrition.

Erythrocyte membrane in protein-energy malnutrition: A23187-induced changes in osmotic fragility of human and rat erythrocytes

Erythrocytes from protein-energy malnourished children have been shown to have increased resistance to osmotic lysis (4). Osmotic fragility studies were carried out in protein-energy malnourished rats and A23187-induced changes in osmotic fragility were studied in rat and human erythrocytes. Rat erythrocytes were found to be much more sensitive to A23187 effect on osmotic fragility as compared to the human erythrocytes. Erythrocytes from protein-deficient rats but not from the energy-restricted rats showed increased resistance to osmotic lysis. A23187 (+ Ca)-induced changes in osmotic fragility were not different between control and experimental erythrocytes, either for humans or rats. There was, however, a difference in the extent to which Na accumulation and K depletion occurred in erythrocytes from control and experimental animals after A23187 + Ca2+ treatment.

Erythrocyte glycolysis in protein-energy malnutrition

Erythrocyte glycolysis has been studied in the anaemia associated with protein-energy malnutrition (PEM) in Kivu. Several results were compatible with a lowering of the mean age of the erythrocyte population, notably raised levels of glucose-6-phosphate, hexokinase, Na+-K+- adenosinetriphosphatases and potassium, and low sodium concentration. Non-significant differences were observed for glucose utilization, lactate formation, and for concentrations of fructose-6-phosphate, fructose-1,6-diphosphate, adenosine diphosphate and pyruvate kinase; there was no gross disturbance of cation transport. The level of adenosine triphosphate was slightly decreased and that of 2,3-bisphosphoglycerate was not elevated, in spite of anaemia. The latter could not be explained by an instability of this metabolite. It is concluded that slight erythrocyte glycolytic abnormalities may occur in the anaemia of Kivu PEM, but that they are not the main cause of the haemolysis observed in this syndrome.

Oxidative haemolysis in protein malnutrition

A study of the haemolytic anaemia observed in protein-energy malnutrition (PEM) in Kivu disclosed the following results. The in vitro resistance to oxidative aggressions of PEM patients' erythrocytes was decreased: when incubated with acetylphenylhydrazine, a higher percentage of the cells showed Heinz bodies, as compared with erythrocytes of local controls. Normal or increased activities were found for certain erythrocyte enzymes involved in the detoxification of activated oxygen: glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and glutathione reductase. The level of reduced glutathione was not decreased. Reduced activities were observed for two enzymes containing trace elements: glutathione peroxidase and superoxide dismutase. It is suggested that the shortened erythrocyte lifespan observed in PEM patients corresponds to an oxidative process which results from the decrease of both enzyme activities. The hypothesis that depletion of trace elements could be responsible for the decreased activity of those enzymes is discussed.