Characterization and Comparison of the Divergent Metabolic Consequences of High-Sugar and High-Fat Diets in Male Wistar Rats.

Diet-induced obesity (DIO) in laboratory rodents can serve as a model with which to study the pathophysiology of obesity, but obesogenic diets (high-sugar and/or high-fat) are often poorly characterised and simplistically aimed at inducing metabolic derangements for the purpose of testing the therapeutic capacity of natural products and other bioactive compounds. Consequently, our understanding of the divergent metabolic responses to different obesogenic diet formulations is limited. The aim of the present study was to characterise and compare differences in the metabolic responses induced by low-fat, medium-fat/high-sugar and high-fat diets in rats through multivariate statistical modelling. Young male Wistar rats were randomly assigned to CON (laboratory chow, low-fat), OB1 (high-sugar, medium-fat) or OB2 (high-fat) dietary groups (n = 24 each) for 17 weeks, after which metabolic responses were characterised. Projection-based multivariate analyses (principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA)) were used to explore the associations between measures of body composition and metabolism. Furthermore, we conducted a systematic literature survey to examine reporting trends in rat dietary intervention studies, and to determine how the metabolic responses observed in the present study compared to other recently published studies. The OB1 and OB2 dietary regimens resulted in distinct metabolic profiles, with OB1 characterised by perturbations in insulin homeostasis and adipose tissue secretory function, while OB2 was characterised by altered lipid and liver metabolism. This work therefore confirms, by means of direct comparison, that differences in dietary composition have a profound impact on metabolic and pathophysiological outcomes in rodent models of DIO. However, through our literature survey we demonstrate that dietary composition is not reported in the majority of rat dietary intervention studies, suggesting that the impact of dietary composition is often not considered during study design or data interpretation. This hampers the usefulness of such studies to provide enhanced mechanistic insights into DIO, and also limits the translatability of such studies within the context of human obesity.

The paracrine effects of adipocytes on lipid metabolism in doxorubicin-treated triple negative breast cancer cells.

Adipocytes in the breast tumour microenvironment promotes acquired treatment resistance. We used an in vitro adipocyte-conditioned media approach to investigate the direct paracrine effects of adipocyte secretory factors on MDA-MB-231 breast cancer cells treated with doxorubicin to clarify the underlying treatment resistance mechanisms. Cell-viability assays, and Western blots were performed to determine alterations in apoptotic, proliferation and lipid metabolism protein markers. Free fatty acids (FFA) and inflammatory markers in the collected treatment-conditioned media were also quantified. Adipocyte secretory factors increased the cell-viability of doxorubicin-treated cells (p < 0.0001), which did not correspond to apoptosis or proliferation pathways. Adipocyte secretory factors increased the protein expression of hormone-sensitive lipase (p < 0.05) in doxorubicin-treated cells. Adipocyte secretory factors increased the utilization of leptin (p < 0.05) and MCP-1 (p < 0.01) proteins and possibly inhibited release of linoleic acid by doxorubicin-treated cells (treatment-conditioned media FFA profiles). Adipocyte secretory factors induced doxorubicin treatment resistance, by increasing the utilization of inflammatory mediators and inhibiting the release of FFA by doxorubicin-treated cells. This further promotes inflammation and lipid metabolic reprogramming (lipid storage) in the tumour microenvironment, which breast cancer cells use to evade the toxic effects induced by doxorubicin and confers to acquired treatment resistance.

Fatty Acid Metabolism and Associations with Insulin Sensitivity Differs Between Black and White South African Women.

PURPOSE: Genetic differences in desaturase genes and consequently fatty acid metabolism have been reported. The aims were to examine ethnic differences in serum fatty acid composition and desaturase indices, and assess the ethnic-specific associations with insulin sensitivity (IS) and liver fat in black and white South African (SA) women. METHODS: In this cross-sectional study including 92 premenopausal black (n = 46) and white (n = 46) SA women, serum fatty acid composition was measured in cholesteryl ester (CE) and nonesterified fatty acid (NEFA) fractions. Desaturase activities were estimated as product-to-precursor ratios: stearoyl-CoA desaturase-1 (SCD1-16, 16:1n-7/16:0); δ-5 desaturase (D5D, 20:4n-6/20:3n-6), and δ-6 desaturase (D6D, 18:3n-6/18:2n-6). Whole-body IS was estimated from an oral glucose tolerance test using the Matsuda index. In a subsample (n = 30), liver fat and hepatic IS were measured by 1H-magnetic resonance spectroscopy and hyperinsulinemic euglycemic clamp, respectively. RESULTS: Despite lower whole-body IS (P = .006), black women had higher CE D5D and lower D6D and SCD1-16 indices than white women (P < .01). CE D6D index was associated with lower IS in white women only (r = -0.31, P = .045), whereas D5D index was associated with higher IS in black women only (r = 0.31, P = .041). In the subsample, D6D and SCD1-16 indices were positively and D5D was negatively associated with liver fat (P < .05). Conversely, CE SCD1-16 was negatively associated with hepatic IS (P < .05), but not independently of liver fat. CONCLUSIONS: Ethnic differences in fatty acid-derived desaturation indices were observed, with insulin-resistant black SA women paradoxically showing a fatty acid pattern typical for higher insulin sensitivity in European populations.

Exercise Training Alters Red Blood Cell Fatty Acid Desaturase Indices and Adipose Tissue Fatty Acid Profile in African Women with Obesity.

OBJECTIVE: This study assessed the changes in red blood cell total phospholipid (RBC-TPL) and subcutaneous adipose tissue (SAT) fatty acid (FA) composition in response to 12 weeks of exercise training in South African women with obesity and the associations with changes in cardiometabolic risk factors. METHODS: Previously sedentary women were randomized into control (n = 15) or exercise (n = 20) groups. RBC-TPL and SAT FA profiles, SAT gene expression, systemic inflammatory markers, liver fat, and insulin sensitivity (SI ) were measured before and after the intervention. RESULTS: Compared with control, exercise training induced decreases in RBC-TPL dihomo-γ-linolenic acid content and stearoyl-CoA desaturase-1 and increased delta-5 desaturase-estimated activity (P < 0.05). In the combined group, these changes correlated with changes in circulating leptin and TNFα (P < 0.05), as well as lower liver fat (P < 0.01). Exercise training decreased saturated FA (lauric and myristic acids) and increased polyunsaturated FA (eicosadienoic and adrenic acids) (P < 0.05) in abdominal SAT, whereas γ-linolenic acid decreased (P < 0.01) in gluteal SAT. These changes in RBC-TPL and SAT FA compositions were not associated with changes in SAT gene expression and SI . CONCLUSIONS: Exercise training alters RBC-TPL desaturase activities, which correlate with lower liver fat and systemic inflammation but not with the improvement of SI .

Decreased Efficacy of Doxorubicin Corresponds With Modifications in Lipid Metabolism Markers and Fatty Acid Profiles in Breast Tumors From Obese vs. Lean Mice.

Breast cancer cells modulate lipid and fatty acid metabolism to sustain proliferation. The role of adipocytes in cancer treatment efficacy remains, however, to be fully elucidated. We investigated whether diet-induced obesity (DIO) affects the efficacy of doxorubicin treatment in a breast tumor-bearing mouse model. Female C57BL6 mice were fed a high fat or low fat diet for the full duration of the study (12 weeks). After 8 weeks, mice were inoculated with E0771 triple-negative breast cancer cells in the fourth mammary gland to develop breast tumor allographs. Tumor-bearing mice received either vehicle (Hank's balanced salt solution) or doxorubicin (chemotherapy). Plasma inflammatory markers, tumor, and mammary adipose tissue fatty acid composition, as well as protein expression of lipid metabolism markers were determined. The high fat diet (HFD) attenuated the treatment efficacy of doxorubicin. Both leptin and resistin concentrations were significantly increased in the HFD group treated with doxorubicin. Suppressed lipogenesis (decreased stearoyl CoA-desaturase-1) and lipolysis (decreased hormone-sensitive lipase) were observed in mammary adipose tissue of the DIO animals, whereas increased expression was observed in the tumor tissue of doxorubicin treated HFD mice. Obesogenic conditions induced altered tissue fatty acid (FA) compositions, which reduced doxorubicin's treatment efficacy. In mammary adipose tissue breast cancer cells suppressed the storage of FAs, thereby increasing the availability of free FAs and favored inflammation under obesogenic conditions.

Correction to: Different effects of γ-linolenic acid (GLA) supplementation on plasma and red blood cell phospholipid fatty acid composition and calcium oxalate kidney stone risk factors in healthy subjects from two race groups with different risk profiles pose questions about the GLA-arachidonic acid-oxaluria metabolic pathway: pilot study.

The authors would like to add the following paragraph in the acknowledgement section of the original version of the paper.

Correction to: Testing the dogma that total phospholipid fatty acid composition of blood plays a role in kidney stone pathogenesis, using a high-low risk human model: results from a pilot study.

The authors would like to add the following paragraph in the acknowledgement section of the original version of the paper.

Testing the dogma that total phospholipid fatty acid composition of blood plays a role in kidney stone pathogenesis, using a high-low risk human model: results from a pilot study.

Previous studies have suggested that ω-3 and ω-6 polyunsaturated fatty acid (PUFA) composition in plasma and red blood cell (RBC) total phospholipids plays a role in urolithiasis. Our aim was to test the robustness of this dogma by retrospectively comparing baseline profiles of these parameters in subjects from high- and low-stone-risk groups. The documented difference in stone occurrence in white (relatively common) (W) and black (rare) (B) subjects prompted us to select these groups as the high-low risk model for the study. Blood and urine samples were obtained from ten subjects in each group and were analysed for PUFAs and stone risk factors, respectively. Concentrations of linoleic acid (LA), eicosadienoic acid (EDA) and arachidonic acid (AA) in plasma and or/RBC total phospholipids were significantly higher in B. Differences in other PUFA profiles were also observed. There was no inter-group difference in AA/LA ratios. Urinary oxalate was significantly higher while urinary phosphate was significantly lower in B. We speculate that elevated AA in B might arise because of a possibly enhanced elongation of LA to EDA, as well as an enhanced ∆-8-desaturation of EDA to dihomo-gamma-linolenic acid (DGLA), which is the immediate precursor of AA. Alternatively, we speculate that the ∆-5-desaturation step of DGLA to AA might be more highly activated in this group. Irrespective of the mechanism, our observed inter-group differences in phospholipid PUFA composition are in conflict with previously published dogma which relates PUFA characteristics to high- and low-stone risk.

Nutrient profile and energy cost of food sold by informal food vendors to learners in primary and secondary schools in the Eastern Cape, South Africa.

OBJECTIVE: To assess type, nutrient profile and cost of food items sold by informal vendors to learners; and to determine nutrient content of corn-based processed snacks frequently sold. DESIGN: Cross-sectional survey. SETTING: Quintile 1 to 3 schools (n 36) randomly selected from six education districts; Eastern Cape, South Africa. PARTICIPANTS: Informal food vendors (n 92) selling inside or immediately outside the school premises. RESULTS: Food items sold at most schools were corn-based processed snacks (94 % of schools), sweets (89 %), lollipops (72 %) and biscuits (62 %). Based on the South African Nutrient Profiling model, none of these foods were profiled as healthy. Foods less commonly sold were fruits (28 % of schools) and animal-source foods; these foods were profiled as healthy. Mean (sd) energy cost (per 418 kJ (100 kcal)) was highest for animal-source foods (R2·95 (1·16)) and lowest for bread and vetkoek (R0·76 (0·21)), snacks (R0·76 (0·30)) and confectionery products (R0·70 (0·28)). The nutrient profiling score was inversely related to the energy cost of the food item (r = -0·562, P = 0·010). Compared with brand-name corn-based processed snacks, non-branded snacks had lower energy (2177 v. 2061 kJ; P = 0·031) content per 100 g. None of the brand-name samples contained sucrose; six of the nine non-branded samples contained sucrose, ranging from 4·4 to 6·2 g/100 g. CONCLUSIONS: Foods mostly sold were unhealthy options, with the healthier food items being more expensive sources of energy.

Hepatic Vitamin A Concentrations in Vervets (Chlorocebus aethiops) Supplemented with Carotenoids Derived from Oil Palm.

Commonly used in biomedical research, vervets (Chlorocebus aethiops) are omnivorous but primarily meet their vitamin A requirements from provitamin A carotenoids. Hypervitaminosis A has occurred in vervets that consume feed high in preformed vitamin A. We investigated the vitamin A status of vervets supplemented daily with various antioxidants derived from palm oil. Male vervets (n = 40) were placed for 23 wk on a high-fat diet (34.9% energy) containing 645 µ g retinol activity equivalents (RAE), with 515 µ g RAE from preformed vitamin A. Vervets were randomized to 5 treatments (duration, 20 mo): control; 100 mg d-α-tocopheryl acetate; 100 mg oil palm (Elaeis guineensis)-derived vitamin E; 50 mg oil palm-derived vitamin E + 50 mg carotenoid complex + unrestricted palm-derived water-soluble antioxidants; and 5) unrestricted water-soluble antioxidants. Livers (n = 38) were analyzed for vitamin A, α-retinol (α-vitamin A), and carotenoids. Median hepatic vitamin A and total carotenoid concentrations were 6.49 µ mol/g and 4.30 nmol/g, respectively. Compared with controls, vervets fed the carotenoid complex had higher hepatic vitamin A (11.9 ± 5.1 µ mol/g), α -vitamin A (1.3 ± 0.7 µ mol/g), α -carotene (11.5 ± 5.3 nmol/g), ß-carotene (15.6 ± 8.6 nmol/g), and total carotenoids (28.1 ± 13.9 nmol/g) but lower lutein (0.66 ± 0.28 nmol/g) and zeaxanthin (0.24 ± 0.06 nmol). NHP may benefit from replacement of preformed vitamin A with carotenoids in feeds; however, bioconversion efficiency in these models should be investigated to determine optimal levels.

An Exercise Intervention to Unravel the Mechanisms Underlying Insulin Resistance in a Cohort of Black South African Women: Protocol for a Randomized Controlled Trial and Baseline Characteristics of Participants.

BACKGROUND: The pathogenesis of type 2 diabetes (T2D) in black African women is complex and differs from that in their white counterparts. However, earlier studies have been cross-sectional and provide little insight into the causal pathways. Exercise training is consistently used as a model to examine the mechanisms underlying insulin resistance and risk for T2D. OBJECTIVE: The objective of the study was to examine the mechanisms underlying the changes in insulin sensitivity and secretion in response to a 12-week exercise intervention in obese black South African (SA) women. METHODS: A total of 45 obese (body mass index, BMI: 30-40 kg/m2) black SA women were randomized into a control (n=22) or experimental (exercise; n=23) group. The exercise group completed 12 weeks of supervised combined aerobic and resistance training (40-60 min, 4 days/week), while the control group maintained their typical physical activity patterns, and both groups were requested not to change their dietary patterns. Before and following the 12-week intervention period, insulin sensitivity and secretion (frequently sampled intravenous glucose tolerance test) and its primary and secondary determinants were measured. Dietary intake, sleep quality and quantity, physical activity, and sedentary behaviors were measured every 4 weeks. RESULTS: The final sample included 20 exercise and 15 control participants. Baseline sociodemographics, cardiorespiratory fitness, anthropometry, cardiometabolic risk factors, physical activity, and diet did not differ between the groups (P>.05). CONCLUSIONS: The study describes a research protocol for an exercise intervention to understand the mechanisms underlying insulin sensitivity and secretion in obese black SA women and aims to identify causal pathways underlying the high prevalence of insulin resistance and risk for T2D in black SA women, targeting specific areas for therapeutic intervention. TRIAL REGISTRATION: Pan African Clinical Trial Registry PACTR201711002789113; http://www.pactr.org/ATMWeb/ appmanager/atm/atmregistry?_nfpb=true&_pageLabel=portals_app_atmregistry_portal_page_13 (Archived by WebCite at http://www.webcitation.org/6xLEFqKr0).

Sensitivity of fatty acid desaturation and elongation to plasma zinc concentration: a randomised controlled trial in Beninese children.

Zn status may affect fatty acid (FA) metabolism because it acts as a cofactor in FA desaturase and elongase enzymes. Zn supplementation affects the FA desaturases of Zn-deficient rats, but whether this occurs in humans is unclear. We evaluated the associations between baseline plasma Zn (PZn) concentration and plasma total phospholipid FA composition, as well as the effect of daily consumption of Zn-fortified water on FA status in Beninese children. A 20-week, double-blind randomised controlled trial was conducted in 186 school age children. The children were randomly assigned to receive a daily portion of Zn-fortified, filtered water delivering on average 2·8 mg Zn/d or non-fortified filtered water. Plasma total phospholipid FA composition was determined using capillary GLC and PZn concentrations by atomic absorption spectrometry. At baseline, PZn correlated positively with dihomo-γ-linolenic acid (DGLA, r 0·182; P=0·024) and the DGLA:linoleic acid (LA) ratio (r 0·293; P<0·000), and negatively with LA (r -0·211; P=0·009) and the arachidonic acid:DGLA ratio (r -0·170; P=0·036). With the intervention, Zn fortification increased nervonic acid (B: 0·109; 95 % CI 0·001, 0·218) in all children (n 186) and more so in children who were Zn-deficient (n 60) at baseline (B: 0·230; 95 % CI 0·023, 0·488). In conclusion, in this study, Zn-fortified filtered water prevented the reduction of nervonic acid composition in the plasma total phospholipids of children, and this effect was stronger in Zn-deficient children. Thus, Zn status may play an important role in FA desaturation and/or elongation.

Chemoresistance: Intricate Interplay Between Breast Tumor Cells and Adipocytes in the Tumor Microenvironment.

Excess adipose tissue is a hallmark of an overweight and/or obese state as well as a primary risk factor for breast cancer development and progression. In an overweight/obese state adipose tissue becomes dysfunctional due to rapid hypertrophy, hyperplasia, and immune cell infiltration which is associated with sustained low-grade inflammation originating from dysfunctional adipokine synthesis. Evidence also supports the role of excess adipose tissue (overweight/obesity) as a casual factor for the development of chemotherapeutic drug resistance. Obesity-mediated effects/modifications may contribute to chemotherapeutic drug resistance by altering drug pharmacokinetics, inducing chronic inflammation, as well as altering tumor-associated adipocyte adipokine secretion. Adipocytes in the breast tumor microenvironment enhance breast tumor cell survival and decrease the efficacy of chemotherapeutic agents, resulting in chemotherapeutic resistance. A well-know chemotherapeutic agent, doxorubicin, has shown to negatively impact adipose tissue homeostasis, affecting adipose tissue/adipocyte functionality and storage. Here, it is implied that doxorubicin disrupts adipose tissue homeostasis affecting the functionality of adipose tissue/adipocytes. Although evidence on the effects of doxorubicin on adipose tissue/adipocytes under obesogenic conditions are lacking, this narrative review explores the potential role of obesity in breast cancer progression and treatment resistance with inflammation as an underlying mechanism.

Different effects of γ-linolenic acid (GLA) supplementation on plasma and red blood cell phospholipid fatty acid composition and calcium oxalate kidney stone risk factors in healthy subjects from two race groups with different risk profiles pose questions about the GLA-arachidonic acid-oxaluria metabolic pathway: pilot study.

Fatty acid (FA) composition of phospholipids in plasma and red blood cells (RBC) can influence calciuria, oxaluria and renal stone formation. In this regard, the ratio of arachidonic acid (AA) and its precursor linoleic acid (LA) appears to be important. Administration of γ-linolenic acid (GLA) has been shown to increase the concentration of dihomo-gamma linoleic acid (DGLA) relative to AA indicating that it may attenuate biosynthesis of the latter. Such effects have not been investigated in race groups having difference stone occurrence rates. Black (B) and white (W) healthy males ingested capsules containing linoleic acid (LA) and GLA, for 30 days. Plasma and RBC total phospholipid (TPL) FA profiles, serum and 24 h urine biomarkers of hypercalciuria and urinary stone risk factors were determined on days 0 and 30. Data were tested for statistical significance using GraphPadInstat version 3.02. Concentration and percentage content of DGLA in plasma TPL increased in W but not in B. Arachidonic acid (AA) did not change in either group. There was no change in calcium excretion in either group but oxalate and citrate excretion increased in W. We suggest that elongation of GLA to DGLA may occur more rapidly than desaturation of DGLA to AA in W and that depressed activity of the enzyme elongase may occur in B. Calciuric and citraturic effects may be dependent on the quantity of LA or on the mass ratio of LA/GLA in the FA supplement. Questions about the mooted DGLA-AA-oxaluria pathway arise. We speculate that there exists a potential for using GLA as a conservative treatment for hypocitraturia. The observation of different responses in B and W indicates that such differences may play a role in stone formation and prevention.

Vitamin A, Iron, and Zinc Content of Fortified Maize Meal and Bread at the Household Level in 4 Areas of South Africa.

BACKGROUND: A national mandatory food fortification program, fortifying wheat flour and maize meal with various micronutrients, was introduced in South Africa in 2003 to address micronutrient deficiencies. OBJECTIVE: This study aimed to determine vitamin A, iron, and zinc content of raw maize meal and wheat flour bread sampled at household level from 2 urban and 2 rural areas in South Africa and to compare with the regulatory minimum requirements. METHODS: Maize meal (250 g) and/or supermarket/local shop bread (3 inner slices) were collected from 50 randomly selected households from each study area. Maize meal samples were reduced to 10 composite samples per area. Bread samples were composited similarly; 1 composite sample consisted of 15 intact slices. Overall, 8 composite samples were obtained for both brown and white bread. The Southern African Grain Laboratory analyzed the samples for vitamin A, iron, and zinc. RESULTS: Mean content of maize meal (100 g) represented ratios of 0.56 to 0.98 of the minimum fortification requirement for vitamin A, 0.76 to 1.08 for iron, and 0.89 to 1.00 for zinc; brown bread (100 g) represented ratios of 0.57, 1.97, and 1.67 of the minimum requirement for vitamin A, iron, and zinc, respectively, and white bread (100 g) represented ratios of 0.89, 2.22, and 2.07 for vitamin A, iron, and zinc, respectively. CONCLUSION: The variation in vitamin A, iron, and zinc content in maize meal and the higher than required iron and zinc content in wheat bread needs to be investigated in further studies.

Vitamin A and anthropometric status of South African preschool children from four areas with known distinct eating patterns.

OBJECTIVE: The aim of this study was to assess the vitamin A and anthropometric status of South African preschool children from four areas with known distinct eating patterns. METHODS: Serum retinol, anthropometric indicators, and dietary intake were determined for randomly selected preschool children from two rural areas, i.e. KwaZulu-Natal (n = 140) and Limpopo (n = 206); an urban area in the Northern Cape (n = 194); and an urban metropolitan area in the Western Cape (n = 207). RESULTS: Serum retinol <20 µg/dL was prevalent in 8.2% to 13.6% children. Between 3% (urban-Northern Cape) and 44.2% (rural-Limpopo) children had received a high-dose vitamin A supplement during the preceding 6 mo. Vitamin A derived from fortified bread and/or maize meal ranged from 65 µg retinol activity equivalents (24%-31% of the Estimated Average Requirement) to 160 µg retinol activity equivalents (58%-76% Estimated Average Requirement). Fortified bread and/or maize meal contributed 57% to 59% of total vitamin A intake in rural children, and 28% to 38% in urban children. Across the four areas, stunting in children ranged from 13.9% to 40.9%; and overweight from 1.2% to 15.1%. CONCLUSION: Prevalence of vitamin A deficiency was lower than national figures, and did not differ across areas despite differences in socioeconomics, dietary intake, and vitamin A supplementation coverage. Rural children benefited more from the national food fortification program in terms of vitamin A intake. Large variations in anthropometric status highlight the importance of targeting specific nutrition interventions, taking into account the double burden of overnutrition and undernutrition.

The potential contribution of bread buns fortified with beta-carotene-rich sweet potato in Central Mozambique.

BACKGROUND: Orange-fleshed sweet potato is an efficacious source of vitamin A. Substituting wheat flour with orange-fleshed sweet potato in processed products could reduce foreign exchange outlays, create new markets for producers, and result in increased vitamin A consumption among consumers provided there is adequate retention of beta-carotene during processing. OBJECTIVE: To explore whether substituting 38% of wheat flour (by weight) in bread buns ("golden bread") with boiled and mashed orange-fleshed sweet potato from fresh roots or rehydrated chips would produce economically viable beta-carotene-rich products acceptable to Mozambican rural consumers. METHODS: Modified local recipes maximized sweet potato content within the limits of consumer acceptability. Sensitivity analysis determined parameters underlying economic viability. Two samples each of buns from five varieties of orange-fleshed sweet potato were analyzed for beta-carotene content. Processed products with at least 15 microg/g product of trans-beta-carotene were considered good sources of vitamin A. RESULTS: Golden bread made from fresh roots of medium-intensity orange-fleshed sweet potato varieties met the good source criterion, but bread from lighter-intensity sweet potato varieties did not. Bread from rehydrated dried chips was not economically viable. Consumers strongly preferred golden bread over pure wheat flour bread because of its heavier texture and attractive appearance. The ratio of the price of wheat flour to that of raw sweet potato root varied from 3.1 to 3.5 among the bakers, whose increase in profit margins ranged from 54% to 92%. CONCLUSIONS: Golden bread is a good source of beta-carotene and is economically viable when the price ratio of wheat flour to raw orange-fleshed sweet potato root is at least 1.5. Widespread adoption during sweet potato harvesting periods is feasible; year-round availability requires storage.

Beta-carotene-rich orange-fleshed sweet potato improves the vitamin A status of primary school children assessed with the modified-relative-dose-response test.

BACKGROUND: Beta-carotene-rich orange-fleshed sweet potato (OFSP) is an excellent source of provitamin A. In many developing countries, sweet potato is a secondary staple food and may play a role in controlling vitamin A deficiency. OBJECTIVE: The objective was to determine the efficacy of daily consumption of boiled and mashed OFSP in improving the vitamin A status of primary school children. DESIGN: Children aged 5-10 y were randomly assigned to 2 groups. The treatment group (n = 90) consumed 125 g boiled and mashed OFSP (1031 retinol activity equivalents/d as beta-carotene), and the control group (n = 90) consumed an equal amount of white-fleshed sweet potato devoid of beta-carotene for 53 school days. All children were dewormed to exclude helminthic infection. The modified-relative-dose-response test for vitamin A status was conducted before and after intervention. RESULTS: The estimated intervention effect for the ratio of 3,4-didehydroretinol to retinol (DR:R) was -0.008 (95% CI: -0.015, -0.001; P = 0.0203), which indicated a greater improvement in vitamin A liver stores in the treatment group than in the control group. The proportions of children with normal vitamin A status (DR:R < 0.060) in the treatment group tended to increase from 78% to 87% (P = 0.096) and did not change significantly (from 86% to 82%) in the control group (P = 0.267). These proportions were not used to test the intervention effect or within-group changes because the study was powered to test the intervention effect on DR:R. CONCLUSIONS: Consumption of OFSP improves vitamin A status and can play a significant role in developing countries as a viable long-term food-based strategy for controlling vitamin A deficiency in children.

Effect of palm olein oil in a moderate-fat diet on low-density lipoprotein composition in non-human primates.

Plasma low-density lipoprotein cholesterol (LDL-C) concentrations in vervet monkeys (Cercopithecus aethiops) can be modulated by the type and amount of fat in the diet. There is, however, a paucity of information on the effect of different types and quantity of dietary fat on the plasma LDL composition in vervets. The objective of this study was to determine the effect of different sources of dietary fat on the concentrations and composition of circulating plasma LDL in vervets consuming moderate-fat diets containing either animal fat, sunflower oil or palm olein. Fifty adult male vervets, never exposed to a Western-type atherogenic diet, were randomly assigned to two groups. For 6 weeks 30 vervets were fed a moderate-fat (28%E) moderate-cholesterol (26 mg cholesterol/1000 kJ) diet (MFD) with a polyunsaturated to saturated fatty acid ratio (P/S) of 0.4; 20 vervets were fed a high-fat (34%E) high-cholesterol (98 mg cholesterol/1000 kJ) diet (HFD) with a P/S ratio of 0.6. Fasting blood samples were collected from all 50 vervets for plasma lipid measurements. The 30 vervets receiving the MFD were stratified into three comparable experimental groups of 10 each according to their LDL-C and high-density lipoprotein cholesterol (HDL-C) concentrations and bodyweight. One group continued with the MFD, in which 11%E was derived from lard (MFD-AF); in the other two groups the lard was substituted isocalorically with either sunflower oil (SO) (MFD-SO) or palm olein oil (PO) (MFD-PO). The three groups were fed the respective experimental diets for 24 months and LDL component concentrations and composition were assessed at 6-monthly intervals. In the long-term study the MFD-AF, MFD-SO and MFD-PO groups showed no significant time-specific group differences at 6, 12, 18 or 24 months with regard to the LDL component concentrations, composition, as well as the LDL molecular weight. As expected, after 6 weeks of dietary exposure the HFD group had significantly higher plasma and lipoprotein total cholesterol, LDL component and apolipoprotein AI concentrations, as well as a higher LDL-C : HDL-C ratio compared to the MFD group (P 0.0005). LDL particle size was not significantly different between the HFD and MFD groups, but the HFD group had significantly fewer triacylglycerol and significantly more unesterified cholesterol molecules per LDL particle compared to the MFD group (P 0.0018). PO in a MFD is no different from AF or SO in its effect on LDL component concentrations, composition or particle size. The increased LDL-C concentration seen with the HFD could be accounted for by a more than two-fold increase in the number of circulating LDL particles and not as a result of enrichment of particles with cholesterol.