Vitamin C in human and guinea pig aqueous, lens and plasma in relation to intake

Taylor, Allen; Jacques, Paul F.; Nowell, Thomas; Perrone, Gayle; Blumberg, Jeffrey B.; Handelman, Garry J.; Jóźwiak, Barbara; Nadler, Daniel J.

doi:10.1076/ceyr.16.9.857.5039

Cited by 60 publications

(44 citation statements)

References 15 publications

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“…This finding is important since it shows that it is possible to alter the lenticular ascorbate concentration with dietary intake. The linear dependence of lens ascorbate concentration on dietary intake in the rat reported in this study is different from the dependence reported in the guinea pig [36]. In the guinea pig, the increase is nonlinear and saturable.…”

Section: Discussioncontrasting

confidence: 55%

“…The method of HPLC with UVR detection has been used for over a decade to analyze ascorbate from a number of tissues and plasma [34]. HPLC with electrochemical detection has been applied to measure ascorbate in the lens tissue from Emory mice [35], guinea pigs and humans [36]. We decided to apply the technique of HPLC with UVR detection to ascorbate measurement in rat lens samples processed and purified using ultrafiltration.…”

Section: Measurement Of Ascorbatementioning

confidence: 99%

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Ascorbate in the Rat Lens: Dependence on Dietary Intake

Mody

Kakar²,

Elfving³

et al. 2005

Ophthalmic Res

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Purpose: To establish a method for sample preparation to measure ascorbate in whole lenses and to investigate whether lens ascorbate concentration is dependent on dietary ascorbate intake. Methods: Four groups of 3 young Sprague-Dawley rats each were fed chow containing L-ascorbate, either 0.0, 5.7, 57.0 or 114.0 mmol/kg for a duration of 4 weeks. Thereafter, each rat was sacrificed. The lens was extracted, photographed, and lens wet weight was measured. The lens was homogenized in 1.0 ml of 0.25% metaphosphoric acid, the homogenate was centrifuged and the supernatant ultrafiltered. The filtrate was injected into an ion exchange, reversed-phase Polypore H HPLC column equipped with a 254-nm ultraviolet detector. Samples were calibrated against an L-ascorbate standard. Polynomial regression analysis was performed on the data. Results: All lenses were devoid of cataract. A 95% confidence interval for baseline content of ascorbate without any dietary intake was estimated to be 0.16 ± 0.01 µmol/g wet weight of lens. The lens ascorbate concentration increased linearly with dietary ascorbate intake with an increased rate, estimated as a 95% confidence interval of 0.33 ± 0.18 (µmol ascorbate) (g lens)^–1(mol ascorbate)^–1 (kg chow) with r² = 0.62. Conclusion: Lens ascorbate concentration linearly increases with dietary ascorbate intake without cataract development in the rat. The currently presented method for sample preparation to measure the whole-lens content of ascorbate is applicable.

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Section: Discussioncontrasting

confidence: 55%

Section: Measurement Of Ascorbatementioning

confidence: 99%

Ascorbate in the Rat Lens: Dependence on Dietary Intake

Mody

Kakar²,

Elfving³

et al. 2005

Ophthalmic Res

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“…These data are consistent with the prior observation that human eye tissues saturate at intakes of vitamin C between 200 and 300 mg/d. 41 The intake data are also supported by our plasma measures that suggest a lower prevalence of nuclear opacification with increasing plasma ascorbic acid concentrations.…”

Section: Plasma Nutrients and Prevalence Of Opacitiesmentioning

confidence: 50%

Long-term Nutrient Intake and Early Age-Related Nuclear Lens Opacities

Jacques

Chylack²,

Hankinson³

et al. 2001

Arch Ophthalmol

185

104

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To assess the relation between usual nutrient intake and subsequently diagnosed age-related nuclear lens opacities.Subjects: Four hundred seventy-eight nondiabetic women aged 53 to 73 years from the Boston, Mass, area without previously diagnosed cataracts sampled from the Nurses' Health Study cohort.Methods: Usual nutrient intake was calculated as the average intake from 5 food frequency questionnaires that were collected during a 13-to 15-year period before the evaluation of lens opacities. The duration of vitamin supplement use was determined from 7 questionnaires collected during this same period. We defined nuclear opacities as a nuclear opalescence grade of 2.5 or higher using the Lens Opacification Classification System III. Results:The prevalence of nuclear opacification was significantly lower in the highest nutrient intake quintile category relative to the lowest quintile category for vitamin C (PϽ.001), vitamin E (P = .02), riboflavin (P=.005), folate (P=.009), ␤-carotene (P=.04), and lutein/ zeaxanthin (P = .03). After adjustment for other nutrients, only vitamin C intake remained significantly associated (P=.003 for trend) with the prevalence of nuclear

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“…Previous studies show that ascorbic acid concentrations are much higher in aqueous humor than in plasma [12, 13]. This concentration gradient is a result of active transport in the ciliary epithelium [14].…”

Section: Discussionmentioning

confidence: 99%

Ascorbic acid concentrations in aqueous humor after systemic vitamin C supplementation in patients with cataract: pilot study

et al. 2017

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BackgroundTo measure ascorbic acid concentration in aqueous humor of patients with cataract after oral or intravenous vitamin C supplementation.MethodsForty-two eyes of 42 patients with senile cataract who underwent uncomplicated cataract surgery were enrolled. Patients (n = 14 each) were administered oral vitamin C (2 g), intravenous vitamin C (20 g) or no treatment (control group) on the day before surgery. Samples of aqueous humor (0.1 cm3) were obtained by anterior chamber aspiration at the beginning of surgery and stored at −80 °C. Ascorbic acid concentration in aqueous humor was measured by high-pressure liquid chromatography.ResultsThe mean age at surgery was 62.5 years, with no difference among the three groups. The mean ± standard deviation concentrations of ascorbic acid in aqueous humor in the control and oral and intravenous vitamin C groups were 1347 ± 331 μmol/L, 1859 ± 408 μmol/L and 2387 ± 445 μmol/L, respectively. Ascorbic acid concentration was significantly lower in the control than in the oral (P < 0.01) and intravenous (P < 0.001) vitamin C groups and was significantly higher in the intravenous than in the oral vitamin C group (P < 0.05).ConclusionsAscorbic acid concentration in aqueous humor is increased by systemic vitamin C supplementation, with intravenous administration being more effective than oral administration.

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Vitamin C in human and guinea pig aqueous, lens and plasma in relation to intake

Cited by 60 publications

References 15 publications

Ascorbate in the Rat Lens: Dependence on Dietary Intake

Ascorbate in the Rat Lens: Dependence on Dietary Intake

Long-term Nutrient Intake and Early Age-Related Nuclear Lens Opacities

Ascorbic acid concentrations in aqueous humor after systemic vitamin C supplementation in patients with cataract: pilot study

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