Assessment of Human Vitamin C Status

Jacob, Robert A.

doi:10.1093/jn/120.suppl_11.1480

Cited by 98 publications

(71 citation statements)

References 18 publications

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“…59 Among other effects, ascorbate deficiency impairs phagocytosis, 56 and some re- ports link vitamin C status with antibody response to viral antigens, lymphocyte blastogenesis, and circulating levels of the immune modulator C1q. 38 Protein deficiency in the impoverished rural children with and without noma ( Table 2) would impair various parameters of specific and nonspecific immunity. 56,60 There are many questions to be answered as to the altered host immunologic responses in the development of noma.…”

Section: Discussionmentioning

confidence: 99%

“…For interpretation of the data, we considered plasma ascorbic acid values Ͻ11 mol/L to signify frank deficiency, values between 11 and 23 mol/L as a marginal or moderate risk of developing clinical deficiency signs, and values Ͼ 23 mol/L as normal. 38 Retinol assay. The measurement of plasma concentration of retinol was done according to the method described by Conley and others, 39 using the Beckman high-performance liquid chromatography (HPLC; Beckman System Gold, 166 Detector, Beckman Instruments).…”

Section: Methodsmentioning

confidence: 99%

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Pathogenesis of cancrum oris (noma): confounding interactions of malnutrition with infection.

Enwonwu¹,

Falkler²,

Idigbe³

et al. 1999

The American Journal of Tropical Medicine and Hygiene

108

129

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Abstract. This study showed that impoverished Nigerian children at risk for cancrum oris (noma) had significantly reduced plasma concentrations of zinc (Ͻ 10.8 mol/L), retinol (Ͻ 1.05 mol/L), ascorbate (Ͻ 11 mol/L), and the essential amino acids, with prominently increased plasma and saliva levels of free cortisol, compared with their healthy counterparts. The nutrient deficiencies, in concert with previously reported widespread viral infections (measles, herpesviruses) in the children, would impair oral mucosal immunity. We postulate, subject to additional studies, that evolution of the oral mucosal ulcers including acute necrotizing gingivitis to noma is triggered by a consortium of microorganisms of which Fusobacterium necrophorum is a key component. Fusobacterium necrophorum elaborates several dermonecrotic toxic metabolites and is acquired by the impoverished children via fecal contamination resulting from shared residential facilities with animals and very poor environmental sanitation.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Pathogenesis of cancrum oris (noma): confounding interactions of malnutrition with infection.

Enwonwu¹,

Falkler²,

Idigbe³

et al. 1999

The American Journal of Tropical Medicine and Hygiene

108

129

View full text Add to dashboard Cite

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“…Moreover, infertile men with specific lifestyles may also be at risk for antioxidant or vitamin deficiency (e.g. smoking, increased alcohol intake, dieting) [45,46].…”

Section: Semen Antioxidants and Sperm Dna Damagementioning

confidence: 99%

Antioxidants and sperm DNA damage: a clinical perspective

Zini

Gabriel

Baazeem

2009

J Assist Reprod Genet

175

110

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Purpose Infertile men possess substantially more sperm DNA damage than do fertile men, damage that may impact negatively on reproductive outcomes. In this era of assisted reproductive technologies there is mounting concern regarding the safety of utilizing DNA-damaged spermatozoa in this setting. Therefore, it is important to identify strategies that may reduce sperm DNA damage. The purpose of this review is to discuss the rationale for antioxidant therapy in men with sperm DNA damage and to evaluate the data on the efficacy of dietary and in vitro antioxidant preparations on sperm DNA damage. Methods We reviewed the literature on antioxidants and sperm DNA damage. Results To date, the data suggest that dietary antioxidants may be beneficial in reducing sperm DNA damage, particularly, in men with high levels of DNA fragmentation. However, the mechanism of action of dietary antioxidants has not been established and most of the clinical studies are small. A beneficial effect of in vitro antioxidant supplements in protecting sperm DNA from exogenous oxidants has been demonstrated, however, the effect of these antioxidants in protecting sperm from endogenous ROS, gentle sperm processing and cryopreservation has not been established.

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“…32 We suspect that infertile men with specific lifestyles (e.g., smoking, increased alcohol intake and dieting) may be at high risk for antioxidant or vitamin deficiency, but this remains to be tested. 33,34 Recently, investigators evaluated dietary antioxidant intake (vitamins C, E or b-carotene) and sperm DNA damage in a cohort of fertile men, but failed to identify any relationships between these parameters. …”

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confidence: 99%

Antioxidant therapy in male infertility: fact or fiction?

Zini¹,

Alhathal²

2011

Asian J Androl

110

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Infertile men have higher levels of semen reactive oxygen species (ROS) than do fertile men. High levels of semen ROS can cause sperm dysfunction, sperm DNA damage and reduced male reproductive potential. This observation has led clinicians to treat infertile men with antioxidant supplements. The purpose of this article is to discuss the rationale for antioxidant therapy in infertile men and to evaluate the data on the efficacy of dietary and in vitro antioxidant preparations on sperm function and DNA damage. To date, most clinical studies suggest that dietary antioxidant supplements are beneficial in terms of improving sperm function and DNA integrity. However, the exact mechanism of action of dietary antioxidants and the optimal dietary supplement have not been established. Moreover, most of the clinical studies are small and few have evaluated pregnancy rates. A beneficial effect of in vitro antioxidant supplements in protecting spermatozoa from exogenous oxidants has been demonstrated in most studies; however, the effect of these antioxidants in protecting sperm from endogenous ROS, gentle sperm processing and cryopreservation has not been established conclusively. Keywords: antioxidant; male infertility; oxidative stress; sperm DNA fragmentation; vitamins RELATIONSHIP BETWEEN OXIDATIVE STRESS AND SPERM DYSFUNCTION Seminal oxidative stress (OS) results from an imbalance between reactive oxygen species (ROS) production and ROS scavenging by seminal antioxidants. Seminal OS is believed to be one of the main factors in the pathogenesis of sperm dysfunction and sperm DNA damage in male infertility.1-4 Indeed, it is estimated that 25% of infertile men possess high levels of semen ROS, whereas fertile men do not have high levels of semen ROS.1,4-6 Although a controlled production of these ROS is required for sperm physiology (sperm hyperactivation, capacitation and acrosome reaction) and for natural fertilization, [7][8][9] the excessive production of ROS by immature germ cells and leukocytes causes sperm dysfunction (lipid peroxidation, loss of motility and sperm DNA damage). 9,10 Spermatozoa are particularly susceptible to oxidative injury due to the abundance of plasma membrane polyunsaturated fatty acids. [10][11][12] These unsaturated fatty acids provide fluidity that is necessary for membrane fusion events (e.g., the acrosome reaction and sperm-egg interaction) and for sperm motility. However, the unsaturated nature of these molecules predisposes them to free radical attack and ongoing lipid peroxidation throughout the sperm plasma membrane. Once this process has been initiated, accumulation of lipid peroxides occurs on the sperm surface (this results in loss of sperm motility) and oxidative damage to DNA can ensue. 13,14SEMINAL ANTIOXIDANT CAPACITY AND SPERM DYSFUNCTION Seminal plasma and spermatozoa themselves are well endowed with an array of protective antioxidants to protect spermatozoa from OS, especially, at the post-testicular level. 6,15,16 Seminal plasma contains a number of high-molecular weigh...

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Assessment of Human Vitamin C Status

Cited by 98 publications

References 18 publications

Pathogenesis of cancrum oris (noma): confounding interactions of malnutrition with infection.

Pathogenesis of cancrum oris (noma): confounding interactions of malnutrition with infection.

Antioxidants and sperm DNA damage: a clinical perspective

Antioxidant therapy in male infertility: fact or fiction?

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