Lack of oxidative stress in a selenium deficient area in Ivory Coast--potential nutritional antioxidant role of crude palm oil

Prevalence of vitamin E inadequacy, dietary intake and sources of alpha-tocopherol, and predictors of alpha- and gamma-tocopherol status in adolescent girls in Central Mozambique

An adequate alpha-tocopherol status is important for females at reproductive age. We studied the dietary intake and sources of alpha-tocopherol and alpha- and gamma-tocopherol status indicators in 14-19-year-old girls in Central Mozambique. We also explored factors associated with alpha- and gamma-tocopherol status. The participants (n 508) were from the cross-sectional ZANE Study that was conducted in 2010. We recruited two separate samples, one in January-February and the other in May-June. We collected venous blood samples and conducted 24 h dietary recall interviews. At the time of blood sampling, 11 % of participants were pregnant and 10 % were lactating. In the total sample, both seasons combined, the median intake of alpha-tocopherol was 6⋅7 mg/d, the mean plasma alpha- and gamma-tocopherol concentrations were 13⋅5 and 0⋅75 μmol/l, respectively, and the prevalence of vitamin E inadequacy (alpha-tocopherol <12 μmol/l) was 36⋅7 % (95 % CI: 31⋅9-42⋅0 %). Season and lactation status were significant predictors of alpha-tocopherol status regardless of which the three indicators (plasma concentration, alpha-tocopherol:total cholesterol ratio, gamma-tocopherol:alpha-tocopherol ratio) were used. Being a lactating mother was negatively associated and having a blood sample taken in January-February, when the main sources of alpha-tocopherol were mango and dark green leafy vegetables, was positively associated with alpha-tocopherol status. In conclusion, vitamin E inadequacy was common in Central Mozambique, and the status may fluctuate due to seasonal changes in the diet. We suggest that lactating mothers are specifically at risk of poor alpha-tocopherol status in resource-poor settings.

A pilot survey of selenium status and its geospatial variation among children and women in three rural districts of Zimbabwe

Introduction

Selenium (Se) deficiency is increasingly recognized as a public health problem in sub-Saharan Africa.

Methods

The current cross-sectional study assessed the prevalence and geospatial patterns of Se deficiency among children aged 6-59 months (n = 741) and women of 15-49 years old (n = 831) selected by simple random sampling in rural Zimbabwe (Murewa, Shamva, and Mutasa districts). Venous blood samples were collected and stored according to World Health Organization guidelines. Plasma Se concentration was determined by inductively coupled plasma-mass spectrometry.

Results

Median, Q1, and Q3 plasma Se concentrations were 61.2, 48.7, and 73.3 μg/L for women and 40.5, 31.3, and 49.5 μg/L for children, respectively. Low plasma Se concentrations (9.41 μg/L in children and 10.20 μg/L in women) indicative of severe Se deficiency risk was observed. Overall, 94.6% of children and 69.8% of women had sub-optimal Se status defined by plasma Se concentrations of <64.8 μg/L and <70 μg/L, respectively.

Discussion

High and widespread Se deficiency among women and children in the three districts is of public health concern and might be prevalent in other rural districts in Zimbabwe. Geostatistical analysis by conditional kriging showed a high risk of Se deficiency and that the Se status in women and children in Murewa, Shamva, and Mutasa districts was driven by short-range variations of up to ⁓12 km. Selenium status was homogenous within each district. However, there was substantial inter-district variation, indicative of marked spatial patterns if the sampling area is scaled up. A nationwide survey that explores the extent and spatial distribution of Se deficiency is warranted.

Linkages between soil, crop, livestock, and human selenium status in Sub-Saharan Africa: a scoping review

Selenium (Se) is essential for human health, however, data on population Se status and agriculture-nutrition-health linkages are limited in sub-Saharan Africa (SSA). The scoping review aims to identify linkages between Se in soils/crops, dietary Se intakes, and livestock and human Se status in SSA. Online databases, organisational websites and grey literature were used to identify articles. Articles were screened at title, abstract and full text levels using eligibility criteria. The search yielded 166 articles from which 112 were excluded during abstract screening and 54 full text articles were assessed for eligibility. The scoping review included 34 primary studies published between 1984 and 2021. The studies covered Se concentrations in soils (n = 7), crops (n = 9), animal tissues (n = 2), livestock (n = 3), and human Se status (n = 15). The evidence showed that soil/crop Se concentrations affected Se concentration in dietary sources, dietary Se intake and biomarkers of Se status. Soil types are a primary driver of human Se status and crop Se concentration correlates positively with biomarkers of Se dietary status. Although data sets of Se concentrations exist across the food system in SSA, there is limited evidence on linkages across the agriculture-nutrition nexus. Extensive research on Se linkages across the food chain is warranted.

Inflammatory, oxidative and DNA damage status in vegetarians: is the future of human diet green?

The health benefit of a vegetarian diet is still under debate as it may result in a higher intake of some beneficial micronutrients, while others may be reduced, thus influencing various metabolic pathways and health-related biomarkers. This scoping review discusses inflammatory, oxidative and DNA damage status in vegetarians and vegans compared to omnivores. Most of the reviewed studies indicated favorable effects of a vegetarian diet on oxidative status compared to omnivores but did not clearly associate particular dietary habits to genome damage. The evidence on the effect of vegetarian diet on the inflammatory and immunological biomarkers is poor, which could at least partly be explained by methodological constraints such as small sample size, short duration of vegetarianism and inconsistent definitions of the omnivorous diet. The only inflammatory biomarker that seems to be associated with the vegetarian diet was inflammatory mediator C-reactive protein, which in several studies showed lower values in vegetarians as compared to omnivores. There were very few studies on immunological markers and the results on the difference between vegetarians and omnivores were inconclusive. Although several biomarkers involved in oxidative stress and inflammation showed a beneficial association with the vegetarian diet, further research in well-defined and sufficiently sized cohorts is needed to provide more evidence.

Selenium deficiency risks in sub-Saharan African food systems and their geospatial linkages

Selenium (Se) is an essential element for human health. However, our knowledge of the prevalence of Se deficiency is less than for other micronutrients of public health concern such as iodine, iron and zinc, especially in sub-Saharan Africa (SSA). Studies of food systems in SSA, in particular in Malawi, have revealed that human Se deficiency risks are widespread and influenced strongly by geography. Direct evidence of Se deficiency risks includes nationally representative data of Se concentrations in blood plasma and urine as population biomarkers of Se status. Long-range geospatial variation in Se deficiency risks has been linked to soil characteristics and their effects on the Se concentration of food crops. Selenium deficiency risks are also linked to socio-economic status including access to animal source foods. This review highlights the need for geospatially-resolved data on the movement of Se and other micronutrients in food systems which span agriculture-nutrition-health disciplinary domains (defined as a GeoNutrition approach). Given that similar drivers of deficiency risks for Se, and other micronutrients, are likely to occur in other countries in SSA and elsewhere, micronutrient surveillance programmes should be designed accordingly.

The risk of selenium deficiency in Malawi is large and varies over multiple spatial scales

Selenium (Se) is an essential human micronutrient. Deficiency of Se decreases the activity of selenoproteins and can compromise immune and thyroid function and cognitive development, and increase risks from non-communicable diseases. The prevalence of Se deficiency is unknown in many countries, especially in sub-Saharan Africa (SSA). Here we report that the risk of Se deficiency in Malawi is large among a nationally representative population of 2,761 people. For example, 62.5% and 29.6% of women of reproductive age (WRA, n = 802) had plasma Se concentrations below the thresholds for the optimal activity of the selenoproteins glutathione peroxidase 3 (GPx3; <86.9 ng mL⁻¹) and iodothyronine deiodinase (IDI; <64.8 ng mL⁻¹), respectively. This is the first nationally representative evidence of widespread Se deficiency in SSA. Geostatistical modelling shows that Se deficiency risks are influenced by soil type, and also by proximity to Lake Malawi where more fish is likely to be consumed. Selenium deficiency should be quantified more widely in existing national micronutrient surveillance programmes in SSA given the marginal additional cost this would incur.

Differential gene expression between wild-type and Gulo-deficient mice supplied with vitamin C

The aim of this study was to test the hypothesis that hepatic vitamin C (VC) levels in VC deficient mice rescued with high doses of VC supplements still do not reach the optimal levels present in wild-type mice. For this, we used a mouse scurvy model (sfx) in which the L-gulonolactone oxidase gene (Gulo) is deleted. Six age- (6 weeks old) and gender- (female) matched wild-type (WT) and sfx mice (rescued by administering 500 mg of VC/L) were used as the control (WT) and treatment (MT) groups (n = 3 for each group), respectively. Total hepatic RNA was used in triplicate microarray assays for each group. EDGE software was used to identify differentially expressed genes and transcriptomic analysis was used to assess the potential genetic regulation of Gulo gene expression. Hepatic VC concentrations in MT mice were significantly lower than in WT mice, even though there were no morphological differences between the two groups. In MT mice, 269 differentially expressed transcripts were detected (≥ twice the difference between MT and WT mice), including 107 up-regulated and 162 down-regulated genes. These differentially expressed genes included stress-related and exclusively/predominantly hepatocyte genes. Transcriptomic analysis identified a major locus on chromosome 18 that regulates Gulo expression. Since three relevant oxidative genes are located within the critical region of this locus we suspect that they are involved in the down-regulation of oxidative activity in sfx mice.

Determinants of homocysteine levels in Ivorian rural population

In the present study, homocysteine (Hcy) and vitamin B status were determined in healthy subjects living in two opposite regions of the Ivory Coast. Fifty-six subjects from a coastal region (Bodou) having a fish-based diet and 56 subjects from a mountainous area (Glanle) having a vegetarian diet were tested to sample Hcy, folate, vitamin B12, creatinine, and lipid levels, as well as inflammation and nutritional parameters. An increased prevalence of Hcy > or = 15 micromol/L was observed, reaching 60 % of all subjects. The Bodou group exhibited significantly higher Hcy levels than the Glanle group [20.1 (9.7 - 41.4) vs. 13.6 (5.5 - 48.7) micromol/L, p<0.0001], despite higher vitamin B12 levels [593 (163 - 1860) vs. 234 (83 - 585) pg/mL, p<0.0001]. Although folate levels were lower in subjects from Bodou compared to Glanle [3.2 (2.0 - 7.3) vs. 6.0 (1.9 - 18.2) ng/mL, p<0.0001], there was no significant relationship with Hcy levels in any groups. Interestingly, there were significantly higher creatinine levels in subjects from Bodou compared to Glanle and a significant positive relationship with Hcy levels was evident in each group. In conclusion, Hcy levels in an Ivorian population having a fish-based diet appeared significantly higher compared to subjects having a vegetarian diet. However, folate and vitamin B12 status did not emerge as the major determinants of this difference; a stronger relationship was observed with creatinine levels.

Tocotrienols: the emerging face of natural vitamin E

Natural vitamin E includes eight chemically distinct molecules: alpha-, beta-, gamma-, and delta-tocopherols and alpha-, beta-, gamma-, and delta-tocotrienols. More than 95% of all studies on vitamin E are directed toward the specific study of alpha-tocopherol. The other forms of natural vitamin E remain poorly understood. The abundance of alpha-tocopherol in the human body and the comparable efficiency of all vitamin E molecules as antioxidants led biologists to neglect the non-tocopherol vitamin E molecules as topics for basic and clinical research. Recent developments warrant a serious reconsideration of this conventional wisdom. The tocotrienol subfamily of natural vitamin E possesses powerful neuroprotective, anticancer, and cholesterol-lowering properties that are often not exhibited by tocopherols. Current developments in vitamin E research clearly indicate that members of the vitamin E family are not redundant with respect to their biological functions. alpha-Tocotrienol, gamma-tocopherol, and delta-tocotrienol have emerged as vitamin E molecules with functions in health and disease that are clearly distinct from that of alpha-tocopherol. At nanomolar concentration, alpha-tocotrienol, not alpha-tocopherol, prevents neurodegeneration. On a concentration basis, this finding represents the most potent of all biological functions exhibited by any natural vitamin E molecule. Recently, it has been suggested that the safe dose of various tocotrienols for human consumption is 200-1000/day. A rapidly expanding body of evidence supports that members of the vitamin E family are functionally unique. In recognition of this fact, title claims in publications should be limited to the specific form of vitamin E studied. For example, evidence for toxicity of a specific form of tocopherol in excess may not be used to conclude that high-dosage "vitamin E" supplementation may increase all-cause mortality. Such conclusion incorrectly implies that tocotrienols are toxic as well under conditions where tocotrienols were not even considered. The current state of knowledge warrants strategic investment into the lesser known forms of vitamin E. This will enable prudent selection of the appropriate vitamin E molecule for studies addressing a specific health need.

Tocotrienols: Vitamin E beyond tocopherols

In nature, eight substances have been found to have vitamin E activity: alpha-, beta-, gamma- and delta-tocopherol; and alpha-, beta-, gamma- and delta-tocotrienol. Yet, of all papers on vitamin E listed in PubMed less than 1% relate to tocotrienols. The abundance of alpha-tocopherol in the human body and the comparable efficiency of all vitamin E molecules as antioxidants, led biologists to neglect the non-tocopherol vitamin E molecules as topics for basic and clinical research. Recent developments warrant a serious reconsideration of this conventional wisdom. Tocotrienols possess powerful neuroprotective, anti-cancer and cholesterol lowering properties that are often not exhibited by tocopherols. Current developments in vitamin E research clearly indicate that members of the vitamin E family are not redundant with respect to their biological functions. alpha-Tocotrienol, gamma-tocopherol, and delta-tocotrienol have emerged as vitamin E molecules with functions in health and disease that are clearly distinct from that of alpha-tocopherol. At nanomolar concentration, alpha-tocotrienol, not alpha-tocopherol, prevents neurodegeneration. On a concentration basis, this finding represents the most potent of all biological functions exhibited by any natural vitamin E molecule. An expanding body of evidence support that members of the vitamin E family are functionally unique. In recognition of this fact, title claims in manuscripts should be limited to the specific form of vitamin E studied. For example, evidence for toxicity of a specific form of tocopherol in excess may not be used to conclude that high-dosage "vitamin E" supplementation may increase all-cause mortality. Such conclusion incorrectly implies that tocotrienols are toxic as well under conditions where tocotrienols were not even considered. The current state of knowledge warrants strategic investment into the lesser known forms of vitamin E. This will enable prudent selection of the appropriate vitamin E molecule for studies addressing a specific need.