Efficacy of a standardized echinacea preparation (Echinilin) for the treatment of the common cold: a randomized, double-blind, placebo-controlled trial.

BACKGROUND: Recently, echinacea has regained popularity as one of the treatments chosen most commonly by consumers with the expectation that it will reduce the severity and duration of the common cold. However, the results from a limited number of clinical trials for this application have thus far been inconclusive. This incongruity may be the result of investigators utilizing poorly standardized echinacea products, likely devoid of sufficient quantities of active constituents necessary to exert a definitive clinical effect. Therefore, a formulation containing alkamides, cichoric acid, and polysaccharides at concentrations of 0.25, 2.5, and 25 mg/mL, respectively, was prepared from freshly harvested Echinacea purpurea plants (commercially available as Echinilin, Natural Factors Nutritional Products, Inc., Vancouver, BC, Canada). The objective of this study was to test the efficacy of this highly standardized formulation in reducing the severity and duration of symptoms of a naturally acquired common cold. METHODS: In a randomized, double-blind, placebo-controlled trial, 282 subjects aged 18-65 years with a history of two or more colds in the previous year, but otherwise in good health, were recruited. The subjects were randomized to receive either echinacea or placebo. They were instructed to start the echinacea or placebo at the onset of the first symptom related to a cold, consuming 10 doses the first day and four doses per day on subsequent days for 7 days. Severity of symptoms (10-point scale: 0, minimum; 9, maximum) and dosing were recorded daily. A nurse examined the subjects on the mornings of days 3 and 8 of their cold. RESULTS: A total of 128 subjects contracted a common cold (59 echinacea, 69 placebo). The total daily symptom scores were found to be 23.1% lower in the echinacea group than in placebo in those who followed all elements of the study protocol (P<0.01). Throughout the treatment period, the response rate to treatments was greater in the echinacea group. A few adverse event profiles were observed in both groups. CONCLUSIONS: Early intervention with a standardized formulation of echinacea resulted in reduced symptom severity in subjects with naturally acquired upper respiratory tract infection. Further studies with larger patient populations appear to be warranted.

Studies on germination conditions and antioxidant contents of wheat grain.

Germination time and conditions for wheat grain were studied to determine optimum conditions that would maximize the production of antioxidants. Wheat grains were first steeped in water for 24 or 48 h, followed by incubation in the dark for 9 d at 98% RH and 16.5 degrees C. The changes in the concentration of vitamins C and E, beta-carotene, ferulic acid and vanillic acid were monitored over the germination period. Vitamins C and E and beta-carotene were barely detectable in the dry grains. However, upon germination the concentrations of these antioxidant vitamins steadily increased with increasing germination time, reaching their peaks after 7 d at 550 mu/g for vitamin C, 10.92 micrograms/g for alpha-tocopherol, and 3.1 micrograms/g for beta-carotene. Concentrations of ferulic and vanillic acids were also increased, reaching their maxima after 7 d at 932.4 micrograms/g and 12.9 micrograms/g, respectively. The grains steeped for 48 h before germination became wet, sticky, yellow-brown color with acidic smell after 7 d. These results suggested that wheat grains steeped for 24 h and germinated for 7 d would produce the most desirable sprouts with respect to antioxidant concentrations and sensory properties.

The immune responses to diabetes in BB rats supplemented with vitamin A.

A substantial amount of evidence suggests that in type I diabetes, vitamin A and zinc status could be of concern because of their impaired metabolic availability. Because both vitamin A and zinc play important roles in the regulation of immune function, the present study was undertaken to examine the immune responses to vitamin A and zinc supplements in diabetic-prone Bio-Breed rats (BBdp), and if the supplements increase the incidence of diabetes. Weanling BBdp rats were fed a NIH-07 diet supplemented with vitamin A either alone or in combination with zinc up to 120 days of age. A greater percentage of rats developing diabetes was found in rats that had supplements of vitamin A and zinc (67%) than those on the basal diet (55%) or with vitamin A supplementation alone (50%). The B cells and macrophages were all markedly increased, whereas CD(4)(+) and CD(8)(+) T cells were decreased at the onset of diabetes. However, this immune status was not changed by vitamin A and zinc supplements. The plasma vitamin A levels were significantly decreased in the presence of diabetes and the vitamin A status did not improve when the rats were given vitamin A and zinc supplements. The Natural Killer cell cytotoxicity on a per-cell basis was significantly decreased in the presence of diabetes, irrespective of supplements with vitamin A and zinc. Overall, results indicated that vitamin A and immune status are both affected by type I diabetes; these effects, however, are not responsive to supplemental intakes of vitamin A either alone or in combination with zinc.

Antioxidant status in children with juvenile rheumatoid arthritis (JRA) living in Cairo, Egypt.

The aim of this study was to examine both enzymatic and non-enzymatic antioxidant status in a select group of children with juvenile rheumatoid arthritis (JRA), living in Cairo, Egypt. The plasma concentrations of albumin, ceruloplasmin, vitamin C, vitamin E as well as erythrocyte superoxide dismutase and whole blood glutathione peroxidase activities were all significantly decreased in the presence of JRA compared to those without JRA. Unlike these antioxidant factors, vitamin A and its carrier (e.g. retinol binding protein), which have very little or no antioxidant property, remained unaffected by JRA. These results suggest that the children with JRA are subject to oxidative stress.

The metabolic availability of vitamin A is decreased at the onset of diabetes in BB rats.

Streptozotocin (STZ)-induced diabetic rats have been associated with an impaired metabolic availability of vitamin A (retinol). This study was undertaken to investigate whether Biobreeding (BB) rats, in which diabetes mellitus resembling human type I diabetes develops spontaneously, respond the same way at the onset of diabetes. Weaning diabetes-prone (BBdp) and normal (BBn) BB rats consumed NIH-07 nonpurified diet ad libitum until 120 d of age. Plasma and hepatic concentrations of retinol and its carriers, retinol-binding protein (RBP) and transthyretin (TTR) were lower in diabetic BB (BBd) rats than in BBn rats. In parallel with RBP, the abundance of mRNA was lower in the liver of BBd rats. Furthermore, the status of zinc, an important factor for the synthesis of RBP, was also disturbed in BBd rats, as indicated by lower circulatory levels and greater urinary excretion. To determine whether the biochemical evidence of vitamin A deficiency in BBd rats could be reversed, BBdp rats were fed a diet supplemented with vitamin A either alone or in combination with zinc. None of these treatments increased plasma vitamin A concentration. The hepatic abundance of RBP mRNA was significantly greater, whereas circulatory RBP concentrations were unaffected by vitamin A plus zinc supplementation. Overall, these results suggest that impaired metabolic availability of vitamin A, possibly caused by its decreased transport from hepatic stores, is another metabolic derangement associated with type I diabetes.

Antioxidant status in children with protein-energy malnutrition (PEM) living in Cairo, Egypt.

OBJECTIVES: Free radicals are implicated in many diseases. The rise in free radicals associated with antioxidant deficiency results in tissue damage. The pathogenesis of oedema and anaemia commonly found in children with protein-energy malnutrition (PEM) has been suggested to be caused by an imbalance between the production of toxic radicals and their safe disposal. The aim of this study was to evaluate antioxidant status in children with PEM. DESIGN: A total of 68 children (age range: 3 months to 3 years) living in Cairo, Egypt were recruited. Forty-six of these subjects had different degrees of PEM; they were admitted at the Abo-Elrish Hospital, Cairo. Of these, 26 children had kwashiorkor (KWO) and twenty had marasmus (MAR). Twenty-two age and sex matched healthy well-nourished children were recruited from the local community, and used as controls. METHODS: The antioxidant status of the study population was determined by measuring copper-zinc superoxide dismutase (Cu-Zn, SOD) in red blood cells, glutathione peroxidase (GPX) in whole blood, and ceruloplasmin in plasma. In addition, the plasma levels of trace-elements involving antioxidant activities, such as copper (Cu), zinc (Zn), and selenium (Se) were determined, along with a select group of vitamins. The latter included vitamin A (retinol), vitamin E (alpha-tocopherol) and vitamin C (ascorbic acid). RESULTS: The mean whole blood GPX activity along with plasma levels of vitamins A, E and C as well as ceruloplasmin, Cu and Se were all lower in children with either KWO or MAR than their corresponding control subjects. The erythrocyte SOD activity, on the other hand, was increased while the plasma Zn concentrations were either increased or not changed in the malnourished children. It was of interest that while haemoglobin concentrations were decreased, the plasma free iron (Fe) levels were significantly increased in children with KWO. CONCLUSIONS: The significant increase in red cell SOD activity associated with the decrease in plasma ceruloplasmin, antioxidant vitamins and the whole blood GPX activity in PEM children suggest that these children are potentially susceptible to high oxidative stress. An elevated plasma Fe concentrations, especially with KWO may augment the harmful effect of free radicals with a clinical consequence of oedema.

Dietary rhubarb (Rheum rhaponticum) stalk fibre stimulates cholesterol 7 alpha-hydroxylase gene expression and bile acid excretion in cholesterol-fed C57BL/6J mice.

Both experimental and clinical studies have indicated that a novel source of dietary fibre, produced from rhubarb (Rheum rhaponticum) stalks, is potentially hypolipidaemic. The present study, using C57BL/6J mice, was undertaken to examine if this fibre source affects cholesterol degradation. Mice were maintained on semi-purified diets containing 50 g rhubarb fibre or cellulose/kg with or without 5 g cholesterol/kg for 4 weeks. In cholesterol-supplemented mice, rhubarb fibre caused significant lowering of plasma cholesterol (-13%) and the hepatic concentrations of total cholesterol (-34%) and cholesteryl esters (-34%). In parallel to the reduction of hepatic cholesteryl ester content, animals fed on rhubarb fibre had significantly lower activity of acyl CoA: cholesterol acyltransferase (EC 2.3.1.26) than the mice maintained on a diet containing cellulose and cholesterol. Rhubarb-fibre feeding accelerated the faecal bile-acid loss and diminished the gall-bladder bile-acid pool in both the normal and the cholesterol-fed mice. The increase in the bile-acid excretion was positively correlated with an increased activity as well as mRNA abundance of cholesterol 7 alpha-hydroxylase (EC 1.14.13.17). The increased excretion of bile acids and induction of cholesterol 7 alpha-hydroxylase activity may account for the hypocholesterolaemic effect of rhubarb fibre.

Perinatal vitamin D and calcium status of northern Canadian mothers and their newborn infants.

OBJECTIVE: This study was undertaken to examine the vitamin D and calcium status of mothers and their newborns. METHODS: The intakes of vitamin D and calcium were determined prenatally in 121 women including 33 Caucasians, 51 Inuits, and 37 Native Indians, living in the Inuvik zone of the Northwest Territories. Plasma concentrations of 25-(OH)-D and calcium were also measured in mothers as well as in their offspring at delivery. RESULTS: The daily mean vitamin D intake of native mothers, including Inuits and Indians, with (8.1+/-5.5 microg) and without supplements (3.4+/-2.5 microg) was significantly lower than that of non-native mothers (13.2+/-5.9 microg and 5.8+/-4.3 microg, respectively). According to the predicted prevalence of low vitamin D intake, there existed a higher risk of vitamin D deficiency without supplementation in both native (88.6% vs 48.4%) and non-native (63.5% vs. 15.1%) mothers. The trend for calcium intakes with and without supplementation was similar to vitamin D intake. At the point of delivery, the plasma levels of 25-(OH)-D were lower in native mothers (50.1 19.3 nmol/L) and their offspring (34.2+/-13.1 nmol/L) than their counterparts (59.8+/-29.4 nmol/L and 41.4+/-23.5 nmol/L, respectively). Its plasma levels in newborn infants averaged only 67% of their mothers. None of these infants showed clinical evidence of vitamin D deficiency. In fact, their plasma calcium levels were significantly higher than their mothers. CONCLUSIONS: Plasma 25-(OH)-D concentrations of 60 to 70% of maternal levels may represent a "normal" range for newborn infants. However, a supplementation in native northern Canadian mothers during pregnancy and in their neonates during infancy may have a role to play in the prevention of vitamin D deficiency.

Longitudinal changes in radial bone density in older men.

OBJECTIVE: To examine changes in radial bone density and biochemical status, with particular reference to calcium, over 18 months in a group of older men. SUBJECTS: Thirty-six healthy men (aged 66 76 y) were recruited to the study during July and August, 1993. These men were free-living residents of Edmonton who were recruited through local organizations for the retired and semi-retired. Data for the younger group of men (age 29-60 y) were taken from a previous study conducted in our laboratory. DESIGN: using special-purpose computed tomography (gammaCT), trabecular (TBD), cortical (CBD) and integral (IBD) bone densities (gm/cm3) were measured in the ultra-distal radius at 6-month intervals over 18 months. At baseline, and at each subsequent study visit, serum was obtained from each subject for determinations of calcium, phosphate, 25-hydroxyvitamin D, alkaline phosphatase, and immunoreactive parathyroid hormone. A 24-h urine sample was also obtained at each study visit for determination of urinary calcium, phosphate and creatinine. RESULTS: In repeated measures analysis of variance of the data for the older men serum 25-hydroxyvitamin D was significantly decreased (P<0.001) over time, while TBD was increased (+0.60% per year, P<0.01). Longitudinal rates of change for TBD, CBD and IBD were: -0.94%, 0.92% and 0.74% per year respectively when bone density data at baseline for the older men and the historical data for younger men were combined. However, separate analyses of the data for the younger and the older men indicated no significant age-related changes in bone density for men aged 29-60 y, or for men aged 66-76 y. However, differences in TBD, CBD and IBD between the younger and older groups of men were significant (P < 0.001). CONCLUSIONS: In a group (n = 36) of older men (mean age 71.7 y) studied longitudinally over 18 months, bone density in the distal radius did not decrease over time. Mean bone density in this group of men was, however, significantly (P < 0.001) lower than in a group of younger men (n = 17, mean age 46.7 y). Regression analysis using cross-sectional bone density data at baseline for the older male group, and historical data for the younger male group, indicates that bone loss occurs with increasing age at a rate of about 1% per year averaged over ages 29-76 y. Bone density variables were not correlated with either height or weight, or with any biochemical or hormonal variable measured in this study.

A physiological level of rhubarb fiber increases proglucagon gene expression and modulates intestinal glucose uptake in rats.

Previous work demonstrated that a high fiber diet upregulates proglucagon mRNA and secretion of glucagon-like peptide-1 [GLP-1(7-37)] and insulin compared with an elemental fiber-free diet. This study examined whether similar intakes of fibers differing in physiochemical and fermentative properties alter the expression of intestinal hormones and intestinal absorptive properties. Sprague-Dawley rats were fed either a 50 g/kg cellulose or rhubarb fiber diet for 14 d. Ileal proglucagon mRNA levels were significantly higher in rats fed rhubarb fiber than in those fed cellulose fiber (9.3 +/- 0.9 vs. 6.2 +/- 1.0 densitometer units). Proglucagon mRNA in the colon did not differ between diet treatments. Plasma c-peptide concentrations were significantly higher 30 min after an oral glucose tolerance test in the rhubarb vs. cellulose group (1627 +/- 67 vs. 1290 +/- 71 pmol/L). Passive permeability, measured by the uptake of L-glucose, was significantly higher in the jejunum of rats fed cellulose compared with those fed rhubarb fiber. Adjusting total glucose uptake for passive permeability and unstirred water layer resistance resulted in a higher Km being calculated for the jejunum and ileum of the cellulose fiber group. Jejunal and ileal carrier-mediated uptakes (Vmax) were not altered by diet and reflected the lack of difference between groups in sodium-dependent glucose cotransporter (SGLT-1) and sodium-independent glucose transporter (GLUT2) mRNA levels. Replacing cellulose fiber with rhubarb fiber in a diet upregulated ileal proglucagon mRNA and resulted in a reduced passive permeability but did not affect glucose transport of the small intestine. This work establishes the importance of dietary fiber fermentability in modulating intestinal proglucagon expression and possibly glucose homeostasis.

Vitamin A homeostasis and diabetes mellitus.

Recent studies have shown that plasma concentrations of vitamin A (retinol) and its carrier proteins, retinol-binding protein (RBP), and transthyretin (TTR), are decreased in human subjects with insulin-dependent (IDDM) but not with noninsulin dependent diabetes mellitus (NIDDM). Rats made diabetic with streptozotocin (STZ) have also been shown to have reduced levels of plasma vitamin A while its hepatic concentrations elevate. The circulatory vitamin A levels remained low while its hepatic concentrations were further elevated following supplementation of the vitamin. The reduced circulatory status of vitamin A in diabetic animals was not caused by its impaired intestinal absorption. Further experimental studies have pointed to the fact that IDDM is associated with a deficiency of vitamin A, which is secondary to an impaired transport mechanism of this vitamin from its hepatic storage to the target site, such as retina of the eyes. The diabetes-associated changes in vitamin A metabolism were reserved to normal by insulin treatment. The underlying cause for decreased metabolic availability in uncontrolled diabetes, is not clearly understood. It appears that the increased hepatic store of vitamin A is attributed to a decreased availability of its carrier proteins. Subnormal vitamin A status in poorly controlled diabetic subjects may not respond to vitamin A supplementation, rather it may increase its load in the liver leading to hepatoxicity. These results clearly suggest that there is need for further research identifying the importance of vitamin A in diabetes mellitus.

Vitamin A (retinol) status of first nation adults with non-insulin-dependent diabetes mellitus.

OBJECTIVE: Poorly controlled insulin-dependent diabetes mellitus (IDDM) has been reported to be associated with an impaired metabolic availability of vitamin A. The purpose of this study was to examine vitamin A status in a select group with non-insulin dependent diabetes mellitus (NIDDM). METHODS: Participants included 106 (male, female, > 40 years) Plains Cree adults residing in central Alberta, with NIDDM (n = 59) and non-diabetic controls (n = 47). Non-fasting plasma samples were collected and concentrations of retinol, zinc, alpha-tocopherol, total protein, albumin, retinol binding protein (RBP), transthyretin (TTR), cholesterol, triglycerides, glucose, insulin, and fructosamine were determined. Multiple linear regression was used to identify predictors of plasma RBP concentration. Three repeated 24-hour recalls and a food frequency questionnaire were used to determine vitamin A intakes. RESULTS: Diabetic subjects had similar intake and plasma concentration of vitamin A compared to controls. Factors such as alpha-tocopherol, zinc, total protein, albumin, and TTR, which are known to influence vitamin A metabolism, also remained unaffected in subjects with diabetes. Plasma levels of vitamin A carrier protein (RBP), however, were elevated in diabetic subjects, possibly as a result of hyperinsulinemia. The subjects with diabetes had many characteristics of the insulin resistant syndrome, including central obesity, hypertension, and hypertriglyceridemia. Poor metabolic control, based on plasma glucose, was a significant predictor of RBP concentration in diabetic subjects. CONCLUSIONS: The plasma concentration of RBP was elevated in diabetic subjects and was associated with normal circulatory availability of retinol. The subjects with NIDDM, characterized by insulin resistance without insulin deficiency, thus, appear to be associated with normal vitamin A status.

Vitamin B-6 normalizes the altered sulfur amino acid status of rats fed diets containing pharmacological levels of niacin without reducing niacin's hypolipidemic effects.

Niacin (nicotinic acid) in large doses (> 2 g) has been increasingly the choice of lipid-lowering agent by clinicians. However, the potential risks of the use of high doses of the vitamin have not been critically considered in the same way as has the use of other lipid-lowering drugs. The present study provides evidence that pharmacological levels of niacin interfere with the metabolism of methionine, leading to hyperhomocysteinemia and hypocysteinemia. Male Sprague-Dawley rats were fed a semisynthetic diet supplemented with either 400 or 4000 mg niacin/kg (compared with 47 mg/kg diet in the control diet). In Experiment 1, feeding these diets for 3 wk resulted in a dose-related increase in the plasma and urine methionine concentrations while cysteine levels were decreased. This altered methionine metabolism was accompanied by a lower plasma vitamin B-6 concentration in niacin-supplemented rats compared with controls. In Experiment 2, the methionine and cysteine levels in plasma and urine were normalized when vitamin B-6 (10 mg/kg diet) was added to the diet containing 4000 mg niacin/kg and fed for 6 wk. This experiment also showed that plasma and urine homocysteine concentrations were increased by niacin and normalized by vitamin B-6. The hypolipidemic action of niacin was unaffected by the presence of vitamin B-6. These results indicate that niacin at large dosages interferes with methionine metabolism by affecting vitamin B-6 status. The treatment of dyslipidemia with simultaneous administration of niacin and vitamin B-6 could be a better therapy than the use of niacin alone.

Cholesterol lowering effects of rhubarb stalk fiber in hypercholesterolemic men.

OBJECTIVE: The present study was undertaken to examine the lipid lowering effects of rhubarb fiber prepared by blanching and drying fresh rhubarb stalks. The new fiber source contained 74% dietary fiber, on dry weight basis, with 66% insoluble and 8% soluble fiber. DESIGN: Ten hypercholesterolemic men were assigned to consume 27 g of ground rhubarb stalk fiber per day for 4 weeks. The dietary intake in terms of total energy, lipid and cholesterol was kept unaltered during the study period. Changes in serum lipid profile were monitored by obtaining blood samples before and after the fiber intervention. RESULTS: Rhubarb fiber supplementation resulted in significant lowering of serum total cholesterol (8%) and low-density lipoprotein (LDL) cholesterol (9%), while high-density lipoprotein cholesterol (HDL) concentrations remained unchanged. The depressed total and LDL cholesterol levels returned to baseline after the fiber supplementation was withdrawn for 1 month. CONCLUSION: The rhubarb stalk fiber is effective in lowering serum cholesterol concentrations, especially LDL cholesterol, in hypercholesterolemic men. These results signify the potential use of underutilized rhubarb crop.

Streptozotocin-induced diabetes lowers retinol-binding protein and transthyretin concentrations in rats.

Retinol-binding protein (RBP) and transthyretin (TTR) in the plasma, liver and kidney, retinol in plasma, and total vitamin A in the liver were measured in rats 6 weeks after diabetes mellitus had been induced by streptozotocin (STZ). The diabetic rats gained 83% less weight despite consuming 45% more feed than the non-diabetic controls. Plasma and kidney concentrations of RBP and TTR were significantly lower in diabetic than in the non-diabetic control rats. Unlike the retinol carrier proteins, plasma albumin concentrations remained unaffected. Plasma concentrations of retinol were decreased while its hepatic levels increased in the diabetic animals. The depressed circulatory levels of retinol may reflect an altered metabolism of its transport proteins.

Folate and vitamin B12 status of the elderly.

OBJECTIVE: The present study was undertaken to investigate the relationship between estimated folate and vitamin B12 intakes and their biochemical status in elderly persons. SUBJECTS: Twenty-eight males and 30 females ( > 65 years) were randomly selected from a larger sample of free-living elderly residents of Edmonton, Canada. Subjects were contacted through a seniors' service organization. Any subject using vitamin supplements or alcohol other than the social drink was excluded from the study. DESIGN: Dietary intake was estimated using a three-nonconsecutive-day food record. Biochemical status was assessed by measuring the plasma levels of folate and vitamin B12, as well as the red blood cell (r.b.c.) folate levels. RESULTS: Average daily intakes of both folate and vitamin B12 met the recommended requirements. Their mean plasma levels were within the accepted normal ranges in both males and females. However, probability analysis of dietary intake revealed an appreciable number of subjects at risk of deficiency, especially of folate (male 26%; female 21%). According to the interpretive guidelines of r.b.c. folate levels, an appreciable number of the study subjects were also found to be at risk of folate deficiency (male 57%; female 67%). CONCLUSIONS: The folate status appears to be a greater concern than the vitamin B12 status for the elderly population. It seems that although mean values of dietary intake and plasma concentrations of folate may indicate nutritional adequacy, a proportion of the older population may still be at nutritional risks.

Streptozotocin-induced diabetes in rats is associated with impaired metabolic availability of vitamin A (retinol).

Using streptozotocin-induced diabetic Wistar rats, studies were carried out to examine the metabolic availability of vitamin A in the plasma, liver and the retina of the eye. Control and diabetic rats were fed ad lib. on a semi-purified diet either with or without (basal) vitamin A supplementation, or pair-fed on the basal diet for 4 weeks. Despite the fact that diabetic rats consumed 48% more feed, they had lower plasma concentrations of retinol (P < 0.003). The decrease in plasma retinol concentration was a response to diabetes (or diabetes-induced trauma), since neither pair-feeding (P < 0.01) nor vitamin A supplementation altered this effect (P < 0.05). Furthermore, the hepatic concentrations of the vitamin in these animals remained elevated and this increase was greater in the supplemented diabetic group (P < 0.001). Decreases in 11-cis retinal (a component of rhodopsin) concentrations in the retina were also observed in diabetic animals. The increased hepatic and the decreased plasma and retina vitamin A levels suggest a defect in the transport of the vitamin from the liver.

Effect of dietary rhubarb stalk fiber on the bioavailability of calcium in rats.

Ground rhubarb stalk fiber containing, on a dry weight basis, 74% total dietary fiber (66% insoluble and 8% soluble) was prepared from rhubarb plants. This fiber source has been shown to have a pronounced lipid lowering effect in mice. Its high oxalic acid content may, however, be a limiting factor for its use. The present study was undertaken to determine the safe dose level of the fiber in terms of its effect on calcium bioavailability. Male weanling Sprague-Dawley rats were fed a semi-purified diet (AIN 76) for 4 weeks containing 0, 1, 3, or 5% rhubarb fiber, or pure oxalic acid equivalent to 5% rhubarb fiber. The fiber content of each diet was brought to 5% by adding cellulose, and the calcium level of all diets was the same. As the rhubarb stalk fiber content of the diet increased, a consistent trend of increasing total retention and apparent absorption of calcium was manifested. In contrast, however, cellulose, due to its increased effect on intestinal motility resulted in a decreased calcium bioavailability. Overall results suggest that an addition of rhubarb stalk powder up to the level of 5% in a diet does not have detrimental effect on calcium bioavailability.

Perinatal vitamin A (retinol) status of northern Canadian mothers and their infants.

Vitamin A (retinol) status was determined in two groups living in the northern part of Canada: native (Indian and Inuit) and non-native (Caucasian). The dietary intake of vitamin A and its plasma concentration were measured prenatally, at delivery and postnatally in mothers. Plasma concentrations were also measured at birth and postnatally in their infants. The mean vitamin A intake of native mothers was significantly lower than that of non-native mothers, 661 +/- 485 versus 1,377 +/- 1,418 retinol equivalents (p < 0.00005), with a higher risk of deficiency without supplementation, 35% versus 8%. Plasma retinol concentrations, although not in the deficient range, were significantly lower in native than non-native mothers prenatally and postnatally. Infant mean plasma retinol concentrations at birth averaged only 52% of those of their mothers and were significantly lower among native than non-native infants although no clinical evidence of vitamin A deficiency was noted. We speculate that vitamin A supplementation in native Northern Canadian mothers during pregnancy and in their neonates during infancy may have a role to play in the prevention of vitamin A deficiency. We also postulate that plasma retinol concentrations of 50-60% of maternal levels and between 0.7 and 2.5 mumol/l represent a 'normal' range for newborn infants.

Strain variation in vitamin A (retinol) status of streptozotocin-induced diabetic rats.

Decreased plasma concentrations of vitamin A (retinol) and retinol-binding protein have been previously identified in human subjects with type I diabetes mellitus. The present study was undertaken to investigate the effects of streptozotocin-induced diabetes in rats of three different strains including Wistar Furth, Sprague Dawley and Wistar, on plasma and liver concentrations of vitamin A. The diabetic animals gained less weight than nondiabetic controls even though they ate 50% more food. The hepatic vitamin A concentration was increased at three weeks after the onset of diabetes in all three strains of rats but the magnitude of increase was greater in Wistar than either Wistar Furth or Sprague Dawley rats. This increased storage of vitamin A in diabetic animals most likely is due to increased food intake. The plasma concentrations of vitamin A, on the other hand, remained unaffected in Wistar Furth and decreased moderately (P < 0.02) in Sprague Dawley but severely (P < 0.0001) in Wistar rats. The fact that the plasma vitamin A levels in diabetic Wistar and Sprague Dawley rats were markedly reduced despite their increased hepatic store suggest an impairment in the transport of vitamin A from the liver. The circulatory levels of vitamin A in Wistar rats are more sensitive to the diabetic state, which is in agreement with those observations seen in diabetic patients. Because of this similarity, it is reasonable to suggest that Wistar should be the choice of rat strain for future experimental studies involving vitamin A and diabetes relationships.