Curcumin Confers Anti-Inflammatory Effects in Adults Who Recovered from COVID-19 and Were Subsequently Vaccinated: A Randomized Controlled Trial.

COVID-19 infection and vaccination offer disparate levels of defense against reinfection and breakthrough infection. This study was designed to examine the effects of curcumin supplementation, specifically HydroCurc (CURC), versus placebo (CON) on circulating inflammatory biomarkers in adults who had previously been diagnosed with COVID-19 and subsequently received a primary series of monovalent vaccine doses. This study was conducted between June 2021 and May 2022. Participants were randomized to receive CURC (500 mg) or CON capsules twice daily for four weeks. Blood sampling was completed at baseline and week-4 and analyzed for biomarkers. Linear regression was utilized to examine the between-group differences in post-trial inflammatory biomarker levels, adjusting for baseline and covariates including age, sex, race/ethnicity, and interval between COVID-19 diagnosis and trial enrollment. The sample (n = 31) was 71% female (Age 27.6 ± 10.4 y). The CURC group exhibited significantly lower post-trial concentrations of proinflammatory IL-6 (ß = -0.52, 95%CI: -1.03, -0.014, p = 0.046) and MCP-1 (ß = -0.12, 95%CI: -0.23, -0.015, p = 0.027) compared to CON, adjusting for baseline and covariates. Curcumin intake confers anti-inflammatory activity and may be a promising prophylactic nutraceutical strategy for COVID-19. These results suggest that 4 weeks of curcumin supplementation resulted in significantly lower concentrations of proinflammatory cytokines in adults who recovered from COVID-19 infection and were subsequently vaccinated.

Vitamin B6 Supplementation Reduces Symptoms of Depression in College Women Taking Oral Contraceptives: A Randomized, Double-Blind Crossover Trial.

Oral contraceptive (OC) users have a heightened risk of low plasma concentrations of vitamin B6, a cofactor in the tryptophan-serotonin pathway critical to mood regulation. The purpose of this crossover study was to determine whether vitamin B6 supplementation reduced symptoms of depression and improved mood states in college women using OC. Participants were healthy (aged 18-25 yrs), did not take dietary supplements, and used OC (estrogen with progestin) consistently for at least 1 year. During the 12-week, randomized, double-blind crossover trial (4-week treatment periods [100 mg vitamin B6 daily or placebo] separated by a 4-week washout) participants (n = 8) maintained normal exercise and eating patterns and recorded tablet consumption daily. The Beck Depression Inventory-II (BDI-II) and Profile of Mood States (POMS) were used to assess mental health before and after each 4-week treatment period. Average dietary vitamin B6 intakes did not vary during the trial (1.2-1.4 mg/d), whereas vitamin B6 status rose significantly following the B6 supplementation period compared to the other three time points. BDI-II scores were reduced 20% by vitamin B6 supplementation in comparison to an 11% rise with placebo ingestion (p = 0.046). POMS scores were not significantly impacted by vitamin B6 supplementation. These preliminary data support a growing literature suggesting the benefits of B6 supplementation for reducing symptoms of depression in young women using OC.

An examination of relationships between vitamin B12 status and functional measures of peripheral neuropathy in young adult vegetarians.

Introduction: Prevalence rates for vitamin B12 deficiency in U.S. adult vegetarians may exceed 30%, which is concerning given the role for this vitamin in numerous nervous system functions, including the synthesis of myelin sheaths. Defective myelin synthesis and repair are directly linked to peripheral neuropathy; yet, few investigations have examined how physical indicators of peripheral neuropathy (e.g., hand dexterity, vibration sensitivity and balance) are impacted in individuals adhering to vegetarian diets. This feasibility research explored the relationships between peripheral neuropathy and vitamin B12 status using a cross-sectional study design. In addition, a small pilot trial was conducted for limited-efficacy testing of vitamin B12 supplementation for reducing peripheral neuropathy. Methods: Healthy, able-bodied adults (n = 38; 19-40 years of age) reported exclusive adherence to a vegetarian or vegan diet for 3 years. Peripheral neuropathy was measured using a force plate for assessing balance, and a vibration sensitivity tester and pegboard tests to assess hand dexterity. Serum vitamin B12 and folate were measured using standard radioimmunoassay techniques. Results: Twenty-six percent of the sample displayed deficient or marginal vitamin B12 status (serum vitamin B12 <221 pmol/L). Participants with adequate vitamin B12 status scored 10% higher on the Purdue pegboard assembly test and 20% higher on the left hand adjusted functional dexterity test in comparison to participants with marginal-to-deficient vitamin B12 status (p < 0.05). Discussion: These data provide preliminary evidence that peripheral neuropathy can be detected in individuals with marginal-to-deficient vitamin B12 status.

Palmitoylethanolamide Reduces Proinflammatory Markers in Unvaccinated Adults Recently Diagnosed with COVID-19: A Randomized Controlled Trial.

BACKGROUND: Inflammation is at the core of many chronic conditions and exacerbates infectious conditions, including the severity of coronavirus disease 2019 (COVID-19) infections. OBJECTIVES: This study aimed to examine the effects of a novel food supplement, palmitoylethanolamide (PEA), specifically Levagen+, as compared with a placebo on proinflammatory biomarkers in adults recently diagnosed with COVID-19 who were unvaccinated and nonhospitalized. METHODS: This study was a double-blind randomized placebo-controlled trial conducted October 2020-March 2021 (clinicaltrials.gov: NCT04912921). Participants aged 19-53 y were unvaccinated and recently infected with COVID-19 as indicated by a positive test result per RT-PCR or antigen test, and they reported to the test site following diagnosis as allowed by the CDC's return-to-work policy. Participants were stratified by age, sex, and BMI and randomly assigned by coin toss to receive 600 mg Levagen+ twice daily (LEV) or placebo tablets twice daily (CON) for 4 wk. At baseline and week 4, participants completed health histories, 24-h dietary recalls, anthropometrics, and nonfasting blood sampling. The primary outcomes were the 4-wk change between groups for IL-6, C-reactive protein, ferritin, intercellular adhesion molecule 1, soluble P-selectin (sP-selectin), and neutrophil/lymphocyte ratio. Multiple linear regression models were utilized to assess treatment effects on outcomes, adjusting for covariates. RESULTS: A total of 60 participants completed the study (LEV: n = 30; CON: n = 30). After 4 wk of supplementation, sP-selectin (ß = -11.5; 95% CI: -19.8, -3.15; P = 0.0078), IL-1ß (ß = -22.9; 95% CI: -42.4, -3.40; P = 0.0222), and IL-2 (ß = -1.73; 95% CI: -3.45, -0.065; P = 0.0492) concentrations were significantly reduced in the LEV group compared with the CON group. CONCLUSIONS: Inflammatory mechanisms are crucial to optimal resolution of infectious conditions, yet unchecked secretion of inflammatory mediators can promote the dysregulated immune response implicated in COVID-19 complications. Overall, PEA supplementation produced anti-inflammatory effects in individuals recently diagnosed with COVID-19 who were nonhospitalized.

Erythrocyte osmotic fragility is not linked to vitamin C nutriture in adults with well-controlled type 2 diabetes.

Erythrocyte fragility is amplified by oxidative stress and linked to diabetes-specific microvascular disease. Vitamin C supplementation improves glycemic indices in adults with type 2 diabetes (T2D) by improving antioxidant status. This cross-sectional study examined the relationships between vitamin C status and erythrocyte osmotic fragility in adults with or without T2D. Participants provided a fasting blood sample for erythrocyte osmotic fragility testing as a function of hypotonic NaCl concentrations. Additionally, plasma was stabilized with metaphosphoric acid prior to vitamin C analysis using isocratic reverse-phase UV-HPLC separation. Participants were grouped as diagnosed T2D (n = 14; 36% female; 55.5 ± 8.2 y; 31.5 ± 9.0 kg/m2; HbA1c: 7.4 ± 1.9%; plasma vitamin C: 36.0 ± 12.2 µM) or no diabetes (n = 16; 69% female; 38.7 ± 13.5 y; 26.8 ± 6.6 kg/m2; HbA1c: 5.4 ± 0.3%; plasma vitamin C: 34.8 ± 10.9 µM). Participant characteristics differed between groups only for age and hemoglobin A1c (HbA1c; p < 0.05). All hemolysis parameters were in normal ranges for the participants with T2D, and no significant differences in hemolysis parameters were noted between those with or without T2D. However, among participants with T2D, the NaCl concentration eliciting 50% hemolysis was higher for those with low (<7%) vs. high (>7%) HbA1c values (p = 0.037) indicating a slightly higher erythrocyte fragility in the former group. Vitamin C status did not impact any of the hemolysis parameters in adults with or without T2D. Thus, erythrocyte fragility was not elevated in T2D, and vitamin C nutriture was not related to erythrocyte fragility in adults with well-controlled T2D.

Evidence That Daily Vinegar Ingestion May Contribute to Erosive Tooth Wear in Adults.

Vinegar ingestion at mealtime is gaining popularity for its antiglycemic effects; however, it is among the most acidic consumable substances. This study examined tooth wear in healthy adults participating in an 8-week randomized trial examining the effect of daily vinegar ingestion on insulin sensitivity and visceral fat reduction. Twice daily participants consumed a vinegar drink (two tablespoons vinegar in a cup of water; 3.6 g acetic acid) or a commercial vinegar pill (control, 0.045 g acetic acid) at mealtime. Participants were screened for dental erosion using the basic erosive wear examination (BEWE) by a blinded registered dental hygienist at trial baseline and week 8. Mean BEWE scores did not change in the control group but increased 18% in the vinegar group over the 8-week study (P = .038). Given the current popularity of vinegar as a medicinal agent, practitioners should caution patients who utilize this strategy on the possibility of erosive tooth wear. Trial registration: This trial was registered at ClinicalTrials.gov (NCT03577834) on July 5, 2018 and the institutional review board at Arizona State University provided ethical approval (STUDY00005418).

No Significant Differences in Muscle Growth and Strength Development When Consuming Soy and Whey Protein Supplements Matched for Leucine Following a 12 Week Resistance Training Program in Men and Women: A Randomized Trial.

There are conflicting reports regarding the efficacy of plant versus animal-derived protein to support muscle and strength development with resistance training. The purpose of this study was to determine whether soy and whey protein supplements matched for leucine would comparably support strength increases and muscle growth following 12 weeks of resistance training. Sixty-one untrained young men (n = 19) and women (n = 42) (18-35 year) enrolled in this study, and 48 completed the trial (17 men, 31 women). All participants engaged in supervised resistance training 3×/week and consumed 19 grams of whey protein isolate or 26 grams of soy protein isolate, both containing 2 g (grams) of leucine. Multi-level modeling indicated that total body mass (0.68 kg; 95% CI: 0.08, 1.29 kg; p < 0.001), lean body mass (1.54 kg; 95% CI: 0.94, 2.15 kg; p < 0.001), and peak torque of leg extensors (40.27 Nm; 95% CI: 28.98, 51.57 Nm, p < 0.001) and flexors (20.44 Nm; 95% CI: 12.10, 28.79 Nm; p < 0.001) increased in both groups. Vastus lateralis muscle thickness tended to increase, but this did not reach statistical significance (0.12 cm; 95% CI: -0.01, 0.26 cm; p = 0.08). No differences between groups were observed (p > 0.05). These data indicate that increases in lean mass and strength in untrained participants are comparable when strength training and supplementing with soy or whey matched for leucine.

Mung Bean Protein Supplement Improves Muscular Strength in Healthy, Underactive Vegetarian Adults.

Although vegetarian diets are considered generally protective against chronic disease, nutrient deficiencies, including protein, are possible due to low bioavailability from plant-based sources. The consequences of inadequate dietary protein include reduced lean body mass (LBM) and muscle weakness. This study examined relationships between protein intake, strength, and LBM in 37 underactive vegetarians and recorded the impact of protein supplementation (18 g/day mung bean protein) on these indices utilizing an eight-week, randomized, controlled, feeding trial. Both handgrip and knee flexor and extensor strength were measured at baseline and week eight. At baseline, LBM was significantly related to grams of protein consumed daily. LBM was also correlated to grip strength (r = 0.569, p < 0.001) and lower body strength (r = 0.763 to 0.784; p < 0.001). Twenty-five vegetarians completed the feeding trial, including 11 in the protein supplementation group (PRO) and 14 in the control group (CON). At the end of the trial, LBM and strength did not differ significantly between groups. However, the average percent change for grip, flexor, and extensor strength did differ between PRO and CON participants (+2.9 ± 7.2% and -2.6 ± 7.3% respectively, p = 0.05). Thus, there were strong associations between dietary protein, LBM, and strength in vegetarians and an indication that supplementary vegetarian protein increased strength in the absence of exercise and independent of LBM.

Plant-Based Nutraceutical Increases Plasma Catalase Activity in Healthy Participants: A Small Double-Blind, Randomized, Placebo-Controlled, Proof of Concept Trial.

Oxidative stress resulting from dietary, lifestyle and environmental factors is strongly associated with tissue damage and aging. It occurs when there is either an overproduction of reactive oxygen species (i.e., oxidants) or decreased bioavailability of antioxidants that can scavenge them. The objective of this 12-week double-blind placebo-controlled study was to assess the efficacy of a nutraceutical at augmenting antioxidant status. Healthy adults (25-45 y) were randomized to either a treatment group (Product B, n = 23) or a placebo group (control, n = 20). No significant effect of Product B was observed for anthropometric variables or markers of glucose and lipid regulation. Biomarkers of oxidative stress were likewise not altered following the 12-week intervention. Plasma catalase concentrations were significantly elevated following 12 weeks of Product B as compared to the control group (+6.1 vs. -10.3 nmol/min/mL, p = 0.038), whereas other measures of antioxidant capacity were not significantly different between the groups. Product B effectively augmented concentrations of the anti-aging antioxidant catalase in healthy adults.

Vitamin D Supplementation Appears to Increase Plasma Aß40 in Vitamin D Insufficient Older Adults: A Pilot Randomized Controlled Trial.

Low plasma amyloid-ß (Aß) is linked to Alzheimer's disease. Since vitamin D cleared brain Aß in vitro, this 8-week trial examined whether vitamin D increased plasma Aß40. Vitamin D insufficient adults (6/18 M/F; 64.3 ± 10.9 y) were randomized to placebo or vitamin (50,000 IU/week) treatments. The vitamin group experienced greater plasma Aß40 change than controls, +14.9 ± 12.0 and +12.8 ± 12.8 pg/mL (p = 0.045; effect size, 0.228). Change in Aß40 for older participants (≥60 y) was +18.3 ± 33.6 and -3.2 ± 44.5 pg/mL for vitamin (n = 4) and placebo (n = 4) groups (effect size, 0.295). Thus, vitamin D may increase plasma Aß, particularly in older adults, suggesting decreased brain Aß.

Vitamin C supplementation slightly improves physical activity levels and reduces cold incidence in men with marginal vitamin C status: a randomized controlled trial.

The early indications of vitamin C deficiency are unremarkable (fatigue, malaise, depression) and may manifest as a reduced desire to be physically active; moreover, hypovitaminosis C may be associated with increased cold duration and severity. This study examined the impact of vitamin C on physical activity and respiratory tract infections during the peak of the cold season. Healthy non-smoking adult men (18-35 years; BMI < 34 kg/m2; plasma vitamin C < 45 µmol/L) received either 1000 mg of vitamin C daily (n = 15) or placebo (n = 13) in a randomized, double-blind, eight-week trial. All participants completed the Wisconsin Upper Respiratory Symptom Survey-21 daily and the Godin Leisure-Time Exercise Questionnaire weekly. In the final two weeks of the trial, the physical activity score rose modestly for the vitamin C group vs. placebo after adjusting for baseline values: +39.6% (95% CI [-4.5,83.7]; p = 0.10). The number of participants reporting cold episodes was 7 and 11 for the vitamin C and placebo groups respectively during the eight-week trial (RR = 0.55; 95% CI [0.33,0.94]; p = 0.04) and cold duration was reduced 59% in the vitamin C versus placebo groups (-3.2 days; 95% CI [-7.0,0.6]; p = 0.06). These data suggest measurable health advantages associated with vitamin C supplementation in a population with adequate-to-low vitamin C status.

Vitamin C status and perception of effort during exercise in obese adults adhering to a calorie-reduced diet.

OBJECTIVE: Moderate energy restriction and exercise are recommended for effective weight loss. Obese individuals oxidize less fat and report a higher perceived exertion during exercise, characteristics that may negatively influence exercise behavior. Because vitamin C status has been linked to fatigability, we compared the effects of vitamin C supplementation on self-reported fatigue and on the respiratory exchange ratio and the Ratings of Perceived Exertion scale during moderate exercise in healthy obese adults adhering to a hypocaloric diet. METHODS: Twenty adults (4 men and 16 women) were stratified and randomly assigned to receive 500 mg of vitamin C (VC) or placebo (CON) daily for 4 wk while adhering to a vitamin C-controlled, calorie-restricted diet. Feelings of general fatigue as assessed by the Profile of Mood States questionnaire were recorded on a separate day from the exercise session at weeks 0 and 4. Participants walked on a treadmill at an intensity of 50% predicted maximal oxygen consumption for 60 min at weeks 0 and 4, and heart rate, respiratory exchange ratio, and Ratings of Perceived Exertion were recorded. RESULTS: After 4 wk, the two groups lost similar amounts of weight (≈ 4 kg), and the respiratory exchange ratio was not altered by group. Heart rate and the Ratings of Perceived Exertion during exercise were significantly decreased in the VC versus the CON group (-11 versus -3 beats/min, P = 0.022, and -1.3 versus +0.1 U, P = 0.001, respectively), and the general fatigue score was decreased 5.9 U for the VC group versus a 1.9 U increase for the CON group (P = 0.001). CONCLUSION: These data provide preliminary evidence that vitamin C status may influence fatigue, heart rate, and perceptions of exertion during moderate exercise in obese individuals.

A preliminary evaluation of the safety and tolerance of medicinally ingested vinegar in individuals with type 2 diabetes.

Vinegar (VIN) ingestion at mealtime reduces postprandial glycemia and may benefit individuals with diabetes; hence, the medicinal use of VIN has increased in recent years. This study examined the safety and tolerance of medicinally ingested VIN in type 2 diabetics. Participants (n = 27) were stratified by gender, age, and body mass and randomized into three groups: commercial VIN pills (the reference treatment [REF] (30 mg of acetic acid daily), pickles (PCK) (approximately 1,400 mg of acetic acid daily), or VIN (2,800 mg of acetic acid daily). Participants continued their normal eating habits during the 12-week trial. At baseline and weeks 6 and 12, fasting blood and urine samples were collected, and adverse changes in bowel movements, frequency of burping or flatulence, and episodes of acid reflux were recorded. Reporting frequency for adverse events did not vary significantly by group during the trial; however, 50-56% of PCK and VIN participants reported at least one treatment-emergent adverse event at week 6 as compared to 11% of REF participants (P = .110). Urinary pH was significantly reduced in VIN participants at week 12 as compared to the other groups (-9% vs. +3% and +2% for the PCK and REF groups, respectively, P = .023). At week 6 there was a tendency for aspartate aminotransferase concentrations to increase in the VIN group as compared to the other groups (+17% vs. +8% and -8% for VIN, PCK, and REF, respectively; P = .090). These data indicate that chronic VIN ingestion may influence hepatic function and metabolic pathways aside from glucose metabolism.

Plasma vitamin C is inversely related to body mass index and waist circumference but not to plasma adiponectin in nonsmoking adults.

We examined the relationships between plasma vitamin C, adiposity, and the collagen-like adipokine, adiponectin. Of 118 sedentary, nonsmoking adults participating in the cross-sectional trial (35 men and 83 women aged 38.7 +/- 1.0 y with BMI of 30.4 +/- 0.6 kg/m2, plasma vitamin C concentrations of 43.5 +/- 1.3 micromol/L, and plasma adiponectin concentrations of 8.9 +/- 0.3 mg/L), 54% were obese and 24% were overweight. Plasma vitamin C was inversely related to BMI, percentage of body fat, and waist circumference in both women and men (r = -0.383 to -0.497, P < 0.025). In women but not men, these associations remained significant after controlling for body mass. Plasma vitamin C was directly related to plasma adiponectin in the women after controlling for age and vitamin C supplement use (r = 0.222, P = 0.049) but not after controlling for body mass. Twenty obese men and women participated in an intervention trial and consumed an energy-restricted diet low in vitamin C (approximately 38 mg/d) for 8 wk. Subjects were stratified by age, gender, and BMI and randomly assigned to receive placebo or vitamin C (500 mg) capsules daily. At baseline, plasma adiponectin was directly related to plasma vitamin C (r = 0.609, P = 0.021) and inversely related to body mass (r = -0.785, P = 0.001). Body mass decreased significantly during the 8 wk study in both the vitamin C (n = 6, -5.9 +/- 0.9 kg) and placebo groups (n = 8, -6.5 +/- 0.7 kg). Plasma adiponectin increased 13% from baseline by wk 8 in both groups (P < 0.05). In summary, plasma vitamin C was inversely related to markers of adiposity, particularly in women, but vitamin C supplementation did not influence the circulating concentration of adiponectin.

Soy isoflavone and ascorbic acid supplementation alone or in combination minimally affect plasma lipid peroxides in healthy postmenopausal women.

The objective of this study was to assess synergistic antioxidant properties of vitamin C and isoflavones. The design was a placebo-controlled crossover trial: 500 mg vitamin C, 5 mg/kg body weight isoflavones, 500 mg vitamin C plus 5 mg/kg body weight isoflavones, or placebo. Total lipid peroxides, plasma vitamin C, and blood pressure were measured. Eight of 10 healthy postmenopausal women completed the study. A multiple analysis of variance was performed and least-squares difference post-hoc test utilized to determine where differences occurred. Significance was defined as P <.05. There was a significant reduction in total lipid peroxides between baseline and isoflavone treatments (3.22+/-0.72 vs 2.47+/-0.82 nmol/mL, P <.05). Mean systolic blood pressure was higher during isoflavone intervention than placebo (117+/-14 vs 125+/-15 mm Hg, P= .042). Supplementation with vitamin C and isoflavones did not produce a synergistic antioxidant effect. A slight but significant increase in systolic blood pressure occurred with isoflavone supplementation. A larger study should be conducted to fully explore the potential interactions between these antioxidants.

Hypertensive crisis associated with high dose soy isoflavone supplementation in a post-menopausal woman: a case report [ISRCTN98074661].

BACKGROUND: Isoflavones are gaining popularity as alternatives to hormone replacement therapy. However, few guidelines exist to inform the public as to an appropriate dose. This case involves a postmenopausal woman who experienced a hypertensive crisis while consuming a high-dose isoflavone supplement as part of a research protocol. CASE PRESENTATION: The participant was part of a placebo-controlled crossover trial to investigate the potential synergism of the antioxidant activity of soy isoflavones and vitamin C. Upon entry into the study, this healthy, well-nourished, normotensive postmenopausal woman (51 years old), consumed the first of four randomly assigned treatments (500 mg vitamin C plus 5 mg/kg body weight soy isoflavones). During this treatment, the participant's systolic blood pressure spiked to a recorded 226/117 mmHg, necessitating medical intervention and discontinuation of study participation. Two plausible mechanisms for this hypertensive crisis are discussed. CONCLUSION: Due to the availability and increasing popularity of soy supplements, practitioners should be aware of the potential side effects associated with their use. Practitioners counseling clients who are consuming soy isoflavone supplements should advise them that elevated blood pressure may be a potential side-effect to consider and monitor.

Vitamins E and C are safe across a broad range of intakes.

A robust database shows that dietary supplements of vitamins E and C are safe for the general population. Because these nutrients supply antioxidant and other functions for homeostasis and protection against free radical damage, supplementation has been intensively studied. Because of perceived benefits, many persons consume quantities of vitamins E and C well above the recommended dietary allowances. As safety guidance, tolerable upper intake levels have been established by the Food and Nutrition Board, Institute of Medicine, at 1000 mg for vitamin E and 2000 mg for vitamin C in adults. Many clinical trials with these vitamins have involved subjects with various diseases, and no consistent pattern of adverse effects has occurred at any intake. Numerous studies of vitamin C supplementation have provided no pattern of evidence to support concerns about safety other than occasional gastrointestinal upset or mild diarrhea resulting from the osmotic effects of unabsorbed quantities of vitamin C. Evidence of bleeding effects and other potential adverse effects of high vitamin E intakes in humans is not convincing. Evidence of adverse effects of vitamin C that result from its effects on iron absorption and metabolism has not been confirmed in clinical trials. Thus, we conclude from clinical trial evidence that vitamin E supplements appear safe for most adults in amounts

Vitamin C deficiency and depletion in the United States: the Third National Health and Nutrition Examination Survey, 1988 to 1994.

OBJECTIVES: We sought to determine prevalence rates of vitamin C deficiency and depletion in the United States. METHODS: We used data from the Third National Health and Nutrition Examination Survey to assess intake of dietary, supplemental, and serum vitamin C. RESULTS: Mean intakes and serum levels of vitamin C were normal; however, vitamin C deficiency and depletion were common (occurring among 5%-17% and 13%-23% of respondents, respectively). Smokers, those who did not use supplements, and non-Hispanic Black males had elevated risks of vitamin C deficiency, while Mexican Americans had lower risks. CONCLUSIONS: Health professionals should recommend consumption of vegetables and fruits rich in vitamin C and should recommend supplementation for individuals at risk of vitamin C deficiency.

Orange juice ingestion and supplemental vitamin C are equally effective at reducing plasma lipid peroxidation in healthy adult women.

OBJECTIVE: To directly examine the contribution of vitamin C to the antioxidant potential of fruits and vegetables, the antioxidant effect of orange juice consumption (8 and 16 fl. oz.) was compared to the antioxidant effect of supplemental vitamin C (dosage equivalent to that supplied by 8 fl. oz. of orange juice). METHODS: Subjects (n = 11; 28.6 +/- 2.1 years) received each treatment in a 3 x 3 randomized crossover design, and each two-week treatment was preceded by a two-week washout. During the entire trial, subjects restricted fruit and vegetable consumption to < or =3 servings per day except the vitamin C-rich foods (items containing >20 mg/serving), which were restricted to < or =3 servings per week. A fasting blood sample was collected at the end of each washout and each treatment period. RESULTS: Following washouts, plasma vitamin C and lipid peroxidation (plasma TBARS) were similar by treatment group and averaged 25.4 +/- 3.6 micromol/L and 3.82 +/- 0.10 nmol/mL respectively. Plasma vitamin C concentrations were similar following each treatment period, 37.9 +/- 8.1, 45.8 +/- 9.4, and 38.3 +/- 12.4 micromol/L for the 8 and 16 fl. oz. orange juice treatments and the supplement treatment, respectively. All intervention treatments reduced plasma TBARS as compared to pretreatment values: -47% (p = 0.013), -40% (p = 0.083), and -46% (p = 0.015) for the 8 and 16 fl. oz. orange juice treatments and supplement treatment respectively. CONCLUSIONS: These data indicate that the regular consumption of 8 fl. oz. orange juice or supplemental vitamin C ( approximately 70 mg/day) effectively reduced a marker of lipid peroxidation in plasma.