Creatine supplementation does not augment muscle carnosine content in type 2 diabetic patients

We examined whether creatine supplementation affects muscle carnosine content in type 2 diabetic patients. Subjects were randomly assigned to receive either creatine (5 g·day(-1)) or placebo in a double-blind fashion. At baseline and after 12 weeks, carnosine content was evaluated in gastrocnemius and soleus muscles by using a 1H-MRS technique. No changes were found in gastrocnemius (p = 0.81) and soleus (p = 0.85). We concluded that creatine supplementation does not augment muscle carnosine content in type 2 diabetic patients.     

Short-term vitamin A supplementation does not affect bone turnover in men

Limited data in humans and animals indicate that excess vitamin A stimulates bone resorption and inhibits bone formation, effects that over time might lead to bone loss and fracture. Thus, it is possible that vitamin A supplementation is a currently unrecognized risk factor for the development of osteoporosis. To further evaluate this possibility, a prospective, randomized, single-blind study of vitamin A supplementation was conducted in 80 healthy men age 18-58 y. One half received 7576 microg (25,000 IU) of retinol palmitate daily with their evening meal; the others took a placebo. Blood was collected from fasting subjects and serum prepared at baseline and after 2, 4 and 6 wk of supplementation. Serum bone specific alkaline phosphatase (BSAP) and N-Telopeptide of type 1 collagen (NTx) were measured at all time points. Serum osteocalcin (Oc) was measured at baseline and after 6 wk of supplementation. BSAP, NTx and Oc did not differ between the supplemented and placebo-treated groups over the course of the study. In conclusion, short-term vitamin A supplementation at this dosage in healthy men does not alter serum markers of skeletal turnover. Thus, it is unlikely that short-term administration of vitamin A would contribute to the development of osteoporosis. Whether long-term vitamin A supplementation might have adverse skeletal effects remains to be determined.     

Calcium supplementation does not augment bone gain in young women consuming diets moderately low in calcium

In earlier observational work, the dietary calcium:protein ratio was directly related to bone accrual in healthy postadolescent women. In this study, we sought to test the hypothesis that augmented calcium intake would increase postadolescent skeletal consolidation, using a double-blind, randomized, placebo-controlled design. We recruited 152 healthy young women (age 23.1 +/- 2.7 y, BMI 22.5 +/- 3.0 kg/m2); their usual diets, as assessed by 7-d food diaries, were low in calcium (605 +/- 181 mg/d; 15.1 +/- 4.5 mmol/d) and in the calcium:protein ratio (10.1 +/- 2.0 mg/g). The subjects were randomly assigned to supplemental calcium [500 mg calcium (12.5 mmol) as the carbonate, 3 times/d, with meals] or placebo capsules identical in appearance; all participants also took a daily multivitamin, and they were followed for up to 36 mo with bone densitometry (dual energy X-ray absorptiometry; DXA) at 6-mo intervals. A total of 121 subjects remained in the study for at least 12 mo (median time in the study, 35 mo), with a mean compliance level (observed/expected tablet consumption) of 87.7%. DXA data for these 121 subjects indicated modest but significant mean rates of increase (i.e., 0.24 to 1.10%/y) in bone mineral content (BMC; total body, total hip, and lumbar spine) and in lumbar spine bone mineral density (BMD) but no change in total hip BMD. None of these rates of change differed by group, i.e., calcium supplementation did not have any measurable effect on bone mass accrual. By midstudy, the calcium content of the subjects' usual diets for both groups had risen by approximately 15%. The combined effect of improved intakes of dietary calcium and the small amount of calcium added by the multivitamin tablets resulted in a mean calcium intake for the control group > 800 mg (20 mmol)/d, possibly at or near the threshold beyond which additional calcium has no further effect on bone accrual.     

Short-term dietary conjugated linoleic acid supplementation does not enhance the recovery of immunodepleted dexamethasone-treated rats

Summary. Background: Conjugated linoleic acid (CLA) has been reported to decrease fat deposition, and increase lean body mass. This has been broadly inferred to mean that CLA alters protein turnover. However, data to test the effects of CLA on protein turnover are lacking. An enhancement in immune responses by CLA has also been demonstrated. Aim of the study: The objective of this study was to determine the potential for dietary CLA and protein intervention to improve nutritional and functional recovery in an animal model of catabolic stress and immunodepletion. Methods: Diets varying in their protein levels in the presence or absence of CLA were tested for their effects on the recovery of glucocorticoid (intraperitoneal injection of dexamethasone, 120 mg/kg) treated rats. Following steroid injection, rats were fed 4 dietary treatments for 4 d. The diets contained 10 or 20 g/100 g protein with or without 0.5 g/100 g CLA. Results: Dexamethasone treatment resulted in a decreased food intake and loss of weight, independent of dietary treatment. A higher number of blood monocytes occurred in rats fed the high CLA diets. The protein fractional synthesis rate in spleens of rats fed the diets containing either high proteins or CLA were higher compared to those fed diets with low protein content or without CLA, respectively. CLA, consumed post-dexamethasone treatment, did not improve protein turnover in the other tissues studied, including gut mucosa, liver, muscle and thymus. Conclusions: The present study was performed to determine the effect of CLA in acute conditions, as opposed to a preventive approach, on the recovery from a catabolic stress with immunodepletion. Overall, no effect of short-term feeding CLA on the recovery from dexamethasone-mediated immunodepletion was observed. Received: 23 July 2002, Accepted: 31 January 2003 Correspondence to: Marco E. Turini     

Prolonged leucine supplementation does not augment muscle mass or affect glycemic control in elderly type 2 diabetic men

The loss of muscle mass with aging has been, at least partly, attributed to a blunted muscle protein synthetic response to food intake. Leucine coingestion has been reported to stimulate postprandial insulin release and augment postprandial muscle protein accretion. We assessed the clinical benefits of 6 mo of leucine supplementation in elderly, type 2 diabetes patients. Sixty elderly males with type 2 diabetes (age, 71 ± 1 y; BMI, 27.3 ± 0.4 kg/m(2)) were administered 2.5 g L-leucine (n = 30) or a placebo (n = 30) with each main meal during 6 mo of nutritional intervention (7.5 g/d leucine or placebo). Body composition, muscle fiber characteristics, muscle strength, glucose homeostasis, and basal plasma amino acid and lipid concentrations were assessed prior to, during, and after intervention. Lean tissue mass did not change or differ between groups and at 0, 3, and 6 mo were 61.9 ± 1.1, 62.2 ± 1.1, and 62.0 ± 1.0 kg, respectively, in the leucine group and 62.2 ± 1.3, 62.2 ± 1.3, and 62.2 ± 1.3 kg in the placebo group. There also were no changes in body fat percentage, muscle strength, and muscle fiber type characteristics. Blood glycosylated hemoglobin did not change or differ between groups and was 7.1 ± 0.1% in the leucine group and 7.2 ± 0.2% in the placebo group. Consistent with this, oral glucose insulin sensitivity and plasma lipid concentrations did not change or differ between groups. We conclude that prolonged leucine supplementation (7.5 g/d) does not modulate body composition, muscle mass, strength, glycemic control, and/or lipidemia in elderly, type 2 diabetes patients who habitually consume adequate dietary protein.     

Short-term creatine supplementation does not reduce increased homocysteine concentration induced by acute exercise in humans

Purpose

The purpose of the study is to evaluate the effects of creatine supplementation on homocysteine (Hcy) plasma levels after acute exercise in humans.

Methods

Twenty-three young (under-20) soccer players were divided into 2 groups: creatine (Cr)- and placebo (Pla)-supplemented groups. The supplementation was performed in double-blind controlled manner using creatine or placebo tablets with 0.3 g/kg during 7 days. Before and after 7 days of supplementation, the athletes performed an acute high-intensity sprint exercise (two consecutive running-based anaerobic sprint test protocol consisted in 6 × 35 m sprint with 10 s between them). Blood samples were collected before and after 7 days of supplementation as well as 0 and 1 h after exercise protocol.

Results

Homocysteine concentration significant increased (P < 0.05) 1 h after acute exercise (18 %). Acute exercise also decreased red blood cell S-adenosylmethionine (SAM) 30 % with no changes in SAM/SAH ratio. Seven days of creatine supplementation were able to increase (P < 0.05) plasma creatine concentration (Pla 130.1 ± 21.7 vs Cr 1,557.2 ± 220.3 μmol/L) as well as decrease (P < 0.05) plasma guanidinoacetic acid (33 %). Controversially, creatine supplementation did not change Hcy plasma level after 7-day supplementation (Pla 6.9 ± 0.2 vs Cr 7.2 ± 0.2 μmol/L) or after acute exercise (Pla 8.2 ± 0.3 vs Cr 8.4 ± 0.3 μmol/L). No changes in plasma vitamin B12 and folate as well as cysteine and methionine were found.

Conclusions

Seven days of creatine supplementation does not avoid increased plasma Hcy induced by acute sprint exercise in humans.     

Selenium supplementation does not alter platelet activation in subjects with normal selenium status

The effect of Se supplementation on the plasma concentrations of platelet specific proteins, beta-thromboglobulin (beta TG) and platelet factor 4 (PF4), was determined in twenty young women with normal selenium (Se) status using a double blind protocol. Selenium supplementation for 4 weeks (150 micrograms/day), did not elevate the initial mean plasma Se level 95 +/- 4 ng/ml above this level, nor did it alter the plasma beta TG/PF4. Moreover, all the other parameters of the body antioxidative status (plasma alpha-tocopherol, retinol and uric acid and whole blood glutathione) measured in this experiment stayed unaltered during the 4-week supplementation period. The results indicate no relationship between Se supplementation and platelet function in subjects with normal Se status.     

Short-term ascorbic acid deficiency does not impair antioxidant status in lens of guinea pigs

We examined whether short-term ascorbic acid deficiency impairs antioxidant status in the lens of guinea pigs. Male guinea pigs aged 4 wk were given a scorbutic diet (20 g/animal per day) with and without ascorbic acid (400 mg/animal per day) in drinking water for 3 wk. The ascorbic acid-deficient group showed no lens opacity. The ascorbic acid-deficient group had 14% of serum ascorbic acid concentration, 6% of aqueous humor ascorbic acid concentration, and 18% of lens ascorbic acid content in the ascorbic acid-adequate group. There were no differences in the contents of lens reduced glutathione and thiobarbituric acid reactive substances, an index of lipid peroxidation, between the ascorbic acid-deficient and adequate groups, while the deficient group had higher lens vitamin E content than the adequate group. The ascorbic acid-deficient group had higher serum vitamin E concentration than the ascorbic acid adequate group, while there were no differences in the concentrations of serum reduced glutathione and tiobarbituric acid reactive substances between the deficient and adequate groups. These results indicate that short-term ascorbic acid deficiency does not impair antioxidant status in the lens of guinea pigs despite induction of severe ascorbic acid depletion in the tissue, which may result in no cataract formation.     

Selenium status in vegans and lactovegetarians

Plasma and urinary selenium were determined among vegans, lactovegetarians and several groups of omnivorous subjects, using gas-liquid chromatography. Plasma Se was lower among lactovegetarians (0.80 (SD 0.18) mumol/l) than in the other groups (0.98 (SD 0.15) mumol/l). This was not related to Se intake, since the vegans had a lower and the lactovegetarians a higher intake of Se than omnivorous subjects in Sweden. Urinary Se was 0.36 (SD 0.10) mumol/d for controls, 0.17 (SD 0.10) mumol/d for vegans and 0.16 (SD 0.07) mumol/d for lactovegetarians. No relation between dietary Se and urinary Se was observed. Among vegetarians, plasma Se and urinary Se were correlated (r 0.51; P less than 0.05).     

Long-term calcium supplementation does not affect the iron status of 12-14-y-old girls

BACKGROUND: Single-meal studies have established that calcium has an acute inhibitory effect on the absorption of iron. However, there is growing evidence that high calcium intakes do not compromise iron status. OBJECTIVE: We evaluated whether long-term calcium supplementation taken with the main meal affected biomarkers of iron status in adolescent girls with high requirements of both iron and calcium. DESIGN: The study was a randomized, double-blind, placebo-controlled trial of supplementation with 500 mg Ca/d for 1 y among 113 adolescent girls aged 13.2 +/- 0.4 y at enrollment. Participants were advised to take the supplement with their evening meal, which usually contributes the majority of dietary iron. Iron status was assessed at baseline and after 1 y of supplementation by measuring hemoglobin and serum concentrations of ferritin and transferrin receptors (TfRs). RESULTS: The mean (+/-SD) hemoglobin at enrollment was 134 +/- 9 g/L, geometric mean serum ferritin was 26.3 microg/L (interquartile range: 18.6-39.4 microg/L), and serum TfR was 4.19 mg/L (3.52-5.10 mg/L). Daily calcium supplementation had no effect on the least-squares mean concentrations of iron-status markers adjusted for their baseline values (hemoglobin: 136 and 134 g/L, P = 0.31; ferritin: 25.4 and 26.1 microg/L, P = 0.73; TfR: 4.1 and 4.4 mg/L, P = 0.12; and the ratio of TfR to ferritin: 160 and 161 in the calcium and placebo groups, respectively; P = 0.97). CONCLUSION: Although it remains to be shown in iron-deficient persons, long-term iron status does not seem to be compromised by high calcium intakes.     

Folic acid supplementation does not prevent ribavirin-induced anemia

Treatment of chronic hepatitis C consists of inteferon plus ribavirin. The major adverse effect of ribavirin is hemolytic anemia, a complication that limits therapy. Folic acid supplementation is used to improve erythropoiesis in chronic hemolytic anemia. The aim of this study was to evaluate the effectiveness of folic acid supplementation in the prevention of ribavirin-induced anemia in patients being treated for hepatitis C. Twenty one patients enrolled in treatment protocols for hepatitis C received folic acid 1 mg daily and 22 did not. Groups were similar in age, gender, ribavirin dose and baseline hemoglobin. Folic acid supplementation had no effect in the decrease in hemoglobin or the measured parameters of hemolysis. No difference between males and females was noted for hemoglobin decrease or lowest hemoglobin levels. In our study, folic acid showed no beneficial effect in the prevention of ribavirin-induced anemia.     

Short-term preoperative supplementation of an immunoenriched diet does not improve clinical outcome in well-nourished patients undergoing abdominal cancer surgery

ObjectiveA recent study suggested that the anti-inflammatory effect of immunonutrition starts after only two d. We therefore investigated the effect of an immunoenriched oral diet administered for three d preoperatively.MethodsIn this prospective, randomized, double-blind, placebo-controlled study, well-nourished patients (Nutrition Risk Screening 2002 <3) with gastrointestinal cancer who were scheduled for major elective abdominal cancer surgery were randomly assigned to either 750 mL of an immunoenriched formula (IEF group) or 750 mL of an isocaloric, isonitrogenous placebo diet (Con group) for 3 consecutive d preoperatively.ResultsA total of 108 patients (IEF group: n = 55; Con group: n = 53) were randomized. The two groups were comparable for all baseline and surgical characteristics. The overall mortality was 2.8% and not significantly different between the two groups (IEF group: 3.6% vs. Con group: 1.9%, P = 1.00). Intention-to-treat analysis showed no difference for the incidence of postoperative overall (IEF group: 29% vs. Con group: 30%; P = 1.00) and infectious (IEF group: 15% vs. Con group: 17%; P = 0.79) complications. Length of hospital stay was 12 ± 4.9 d in the IEF group and 11.6 ± 5.3 d in the Con group (P = 0.68).ConclusionsPreoperative oral supplementation with an immunoenriched diet for 3 d preoperatively did not improve postoperative outcome compared with the placebo in well-nourished patients with elective gastrointestinal cancer surgery.     

Iron supplementation does not affect the susceptibility of LDL to oxidative modification in women with low iron status

Elevated iron stores may or may not promote atherogenesis by increasing free radical formation and oxidative stress, but controlled diet and supplement trials are lacking. We tested the hypothesis that iron supplementation does not increase the susceptibility of LDL to undergo oxidative modification in women with low iron status. A randomized, double-blind, 2-period crossover study design (n=26) was used to examine the effects of the following diets on measures of LDL oxidation: average American diet (AAD) [36% of energy as fat; 15% saturated fatty acids (SFA)], and a Step 2 diet (26% fat; 7% SFA). In addition, subjects received either a supplement containing 160 mg of ferrous sulfate (50 mg elemental iron) or a placebo twice daily [supplement group received a total of 320 mg ferrous sulfate (100 mg elemental iron) daily]. After supplementation, serum ferritin differed between the supplement and placebo groups (P=0.008). Measures of LDL oxidation were not affected by supplement intake; however, they were affected by diet. Lag time was shorter after the women consumed the AAD diet than after the Step 2 diet (P<0.0001). The diets did not affect the rate of oxidation or total dienes. Although iron status was improved by aggressive iron supplementation, LDL oxidative susceptibility was not affected. As expected, lag time was increased after the women consumed the low fat, low SFA diet. Therefore, the results of this study do not support a relationship between iron status and LDL oxidation.     

Postweaning carnitine supplementation of iron-deficient rats

Severe iron deficiency in the suckling and weanling rat is associated with lipid accumulation in serum and liver, impaired ketogenesis in the suckling pup and low levels of carnitine in some tissues. Carnitine has been effective in reducing high triacylglycerol levels in humans and rats. This study examined tissue triacylglycerol concentrations of iron-deficient rats supplemented with carnitine or iron. Iron-adequate (C) and iron-deficient (D) pups were weaned to diets containing 38 ppm Fe (c) or 6 ppm Fe (d) with or without 0.2% DL-carnitine (Carn) resulting in six experimental treatments: CcCarn, DdCarn, Cc, Cd, Dc, Dd. Males received the diets for 2 wk and female littermates for 4. After 2 and 4 wk, carnitine supplementation significantly increased carnitine content in liver, heart and skeletal muscle by 30-60% in rats from control and Fe-deficient dams. Carnitine treatment significantly lowered the triacylglycerol level in liver of 49-d-old Fe-deficient females, but did not affect other tissues at either time point compared to other dietary treatments. Fe supplementation did not increase carnitine content in tissues, but did reduce triacylglycerol levels in liver by 4 wk and in skeletal muscle at both time points. Possible mechanisms by which iron and carnitine may lower lipids are discussed.     

Biotin nutritional status of vegans, lactoovovegetarians, and nonvegetarians

Urinary excretion of biotin (total avidin-binding substances) was measured in adults and children who were adhering to one of the following self-selected diets: strict vegetarian (vegan), lactoovovegetarian, or mixed (containing meat and dairy products as well as plant-derived foods). In a subset of subjects, plasma biotin concentrations were also measured. In adults the biotin excretion rate was significantly greater in the vegan group than in either the lactoovovegetarian or the mixed-diet groups; the latter were not significantly different from one another. In children the biotin excretion rates in both the vegan group and the lactoovovegetarin group were significantly greater than in the mixed-diet group. A similar trend (vegan greater than lactoovovegetarian greater than mixed) was detected in the plasma concentrations of biotin of adults and children but differences were not generally statistically significant. These observations provide evidence that the biotin nutritional status of vegans is not impaired.     

Caffeine, carnitine and choline supplementation of rats decreases body fat and serum leptin concentration as does exercise

The effect of a combination of caffeine, carnitine and choline with or without exercise on changes in body weight, fat pad mass, serum leptin concentration and metabolic indices was determined in 20 male, 7-wk-old Sprague-Dawley rats. They were given free access to a nonpurified diet without or with caffeine, carnitine and choline at concentrations of 0.1, 5 and 11.5 g/kg diet, respectively. In a 2x2 factorial design, one-half of each dietary group was exercised, and the other half was sedentary. Body weight and food intake of all rats were measured every day for 28 d. Rats were killed and blood and tissue samples were collected and analyzed for biochemical markers. Food intake of the groups was not different, but the body weight was significantly reduced by exercise in both dietary groups. Fat pad weights and total lipids of epididymal, inguinal and perirenal regions were significantly reduced by the supplements as well as by exercise. Regardless of exercise, supplements significantly lowered triglycerides in serum but increased levels in skeletal muscle. Serum leptin concentrations were equally lowered by supplements and exercise. Serum leptin was correlated with body weight (r = 0.55, P< or =0.01), fat pad weight (r = 0.82, P< or =0.001) and serum glucose (r = 0.51, P< or =0.05). We conclude that the indices of body fat loss due to dietary supplements were similar to those due to mild exercise, and there were no interactive effects of the two variables.     

Dietary carnitine intake and carnitine status in endurance-trained males

Background: Carnitine is an integral component of fatty acid transfer into the mitochondria, and also buffers excess intramitochondrial acyl‐CoA. It has previously been suggested that athletes may be at risk of low carnitine status and could therefore benefit from carnitine supplementation. Objective: To report the habitual dietary carnitine intakes of endurance‐trained adult males, and to determine whether they are at risk of carnitine insufficiency by measuring plasma and urinary carnitine concentrations. Methods: Fourteen non‐vegetarian endurance‐trained males completed a seven‐day weighed food record and exercise logs to determine habitual dietary carnitine intake. Resting venous blood samples and 24‐hour urine collections were used to determine plasma carnitine concentration and urinary carnitine excretion. Results: The mean dietary carnitine intake was 64 (range 21–110) mg/day. Mean ± SD resting plasma total carnitine was 44 ± 7 µmol/L and acyl : free carnitine ratio was 0.28 ± 0.11, which were within normal ranges. Urinary carnitine excretion was 437 ± 236 µmol/day. There was no correlation between dietary carnitine intake or dietary macro‐ and micronutrients and plasma carnitine or urinary carnitine excretion. Conclusion: The results of the present study indicate there is no evidence that endurance‐trained males consuming a mixed diet are at risk of carnitine insufficiency.