Vitamin C and Cancer - Medicine or Politics?

2010

in 1976 an article co-authored by linus Pauling described that 100 terminal cancer patients treated with intravenous vitamin c, followed by oral maintenance, lived four times longer than a control group of 1,000 patients who did not receive vitamin c. the study was strongly criticized because the control group was very different from the group treated with vitamin c. the latter were declared terminally ill much sooner than the control group thus resulting in an artificially longer survival for the vitamin c group. three double blind placebo controlled randomized trials performed at Mayo clinic using oral vitamin c for cancer patients were negative. in a phase i-ii trial performed by riordan et al, none of 24 cancer patients treated with iv vitamin c responded. at this point we don't have information as to which is the actual plasma level of vitamin c that can produce tumor shrinkage. we don't have consistent information either regarding what is the clinical dose necessary to...

PR Health Sci J, 2010

Journal of restorative medicine, 2019

Frontiers in Bioscience, 2013

Though most animals are able to endogenously synthesize large quantities of vitamin C, humans do not have the capability to synthesize vitamin C due to a series of mutations of the gene encoding gulonolactone oxidase which catalyses the last enzymatic step in ascorbate synthesis (3, 4). However, the requirement for vitamin C is satisfied by natural sources and vitamin C supplements existing in the ordinary diet. The lack of vitamin C causes scurvy, a pathological condition leading to blood vessel fragility, connective tissue damage, fatigue, and, finally, death. In addition to poor dietary intake of vitamin C, alcoholism (5), elderly age, socioeconomic deprivation (6), mental illness , malabsorption disorders, kidney failure, hemodialysis (8), and peritoneal dialysis (9) have been identified as risk factors for low vitamin C endogen levels and developing clinical symptoms of scurvy (10-12). Intake of 10 mg per day of vitamin C is appropriate to prevent scurvy. This amount results in plasma concentrations of vitamin below 10 µM, already higher than that necessary to prevent scurvy (13). However, the current recommended dietary allowance (RDA) for vitamin C for adult men and women, is set at 75 mg/day for women and 90 mg/day for men .

2021

Vitamin C is associated with history of the cause of the ancient hemorrhagic disease scurvy. Vitamin C is an essential nutrient with important antioxidant properties. It is required by the body for normal physiological function. The body cannot synthesize vitamin C, it is present in nature through foods and other natural sources and it exists as a nutritional food supplement. The antioxidant activity of vitamin C protects the body from free radical damage. Vitamin C is essential for the development and maintenance of connective tissues. It is used as therapeutic agent in many diseases and disorders. Vitamin C plays an important role in several metabolic functions, as the conversion of the amino acid, tryptophan, to the neurotransmitter, serotonin, and the conversion of cholesterol to bile acids. Vitamin C supplementation resulted in a significant increase in vitamin C levels in populations; its high intake is associated with positive effects on cardiovascular risk factors. Vitamin C...

Genes & Nutrition, 2011

Although vitamin C deficiency and scurvy are generally considered as pure nutritional disorders, only a minority of the vitamin C concentration is determined by food intake. In the presence of transition metals (iron and copper), the antiscorbutic factor shifts from an antioxidant to a pro-oxidant function. Haptoglobin (Hp) is a plasma α-2 glycoprotein characterized by 3 common phenotypes (Hp 1–1, Hp 2–1 and Hp 2–2). Its free hemoglobin (Hb)-binding capacity prevents Hb-driven oxidative damage. When the antioxidant capacity of Hp is insufficient, its role is taken over by hemopexin (heme-binding protein) and by vitamin C (free radical scavenger). The Hp 2–2 phenotype has a lower capacity to inhibit oxidation and vitamin C depletion. In this article, two consequences of this major finding are tackled. The Hp polymorphism is an important non-nutritional modifying factor in the pathogenesis of vitamin C deficiency and scurvy, which may explain the success of long-range human migration by the natural selection of some populations characterized by high Hp 1 allele frequencies. Moreover, we propose tailoring the recommended dietary allowance (RDA) values of vitamin C, taking into consideration the Hp phenotype dependency.

American Journal of Epidemiology, 2009

A cross-sectional study of the 979 nonsmoking women and men aged 20-29 years who participated in the Toronto Nutrigenomics and Health Study from 2004 to 2008 was conducted to determine the prevalence of serum ascorbic acid (vitamin C) deficiency and its association with markers of chronic disease in a population of young Canadian adults. High performance liquid chromatography was used to determine serum ascorbic acid concentrations from overnight fasting blood samples. A 1-month, 196-item food frequency questionnaire was used to assess dietary intakes. Results showed that 53% of subjects had adequate, 33% had suboptimal, and 14% had deficient levels of serum ascorbic acid. Subjects with deficiency had significantly higher measurements of mean C-reactive protein, waist circumference, body mass index, and blood pressure than did subjects with adequate levels of serum ascorbic acid. The odds ratio for serum ascorbic acid deficiency was 3.43 (95% confidence interval: 2.14, 5.50) for subjects who reported not meeting the recommended daily intake of vitamin C compared with those who did. Results suggest that 1 of 7 young adults has serum ascorbic acid deficiency, in part, because of unmet recommended dietary intakes. Furthermore, serum ascorbic acid deficiency is associated with elevated markers of chronic disease in this population of young adults, which may have long-term adverse health consequences. ascorbic acid; biological markers; chronic disease; ethnic groups; scurvy Abbreviation: RDA, recommended dietary allowance.

Journal of Food and Nutrition Research

Vitamin C is effective in strengthening the immune system, capillary blood vessels and protecting the dental health, as well as in the convenient use of iron, calcium, thiamine, riboflavin, folic acid, vitamin A and E in the body. Vitamin C also acts as a cofactor for 15 different enzymes, and shows antioxidant activity as a electron donor reducing agent. It acts as a powerful free radical scavenger by protecting tissues against oxidative stress and reduces inflammation. Obesity is defined as "mild inflammatory disease" due to the increase in inflammatory markers such as C reactive protein (CRP), tumor necrosis factor alpha (TNF) and IL-6. Since antioxidant enzyme activity and serum antioxidant levels decrease in obese individuals, the effect of antioxidant vitamins on weight loss is further investigated. In studies investigating the effectiveness of vitamin C in the treatment of obesity; vitamin C was found to reduce systemic inflammation by inhibiting CRP and TNF alpha pathways, shown to inhibit the hypoxia in adipose tissue with potential for protection against free radicals and decreasing lipid peroxidation. On the other hand, it was shown that vitamin C inhibits mature adipocyte formation and cell growth, inhibits lipolysis, and can be considered as a treatment model for obesity to offer solutions for abnormal fat accumulation. In this review, the action mechanism of vitamin C and its role in dietary treatment were investigated in order to prevent obesity complications and to provide weight loss.

2000

In the last couple of days, vitamin C and cancer has become a hot news topic. For people who have followed this matter, the media's sudden interest comes as something of a surprise: the evidence that vitamin C is a selective anticancer agent has been known for decades. This story is important, as it illustrates how the head-in-the-sand conventional view

AIMS medical science, 2015

Vitamin C or ascorbic acid has been proposed as an anticancer agent, as an intervention to reduce cancer incidence, and also as a medication to reduce cancer treatment-related side effects. While there has been significant basic science research that has evaluated the potential tumoricidal mechanisms of action, clinical studies have been underpowered, retrospective, or poorly designed. Current systematic reviews have suggested that the outcome data from vitamin C therapy is limited. There is an important need for prospective clinical trials and pharmacologic studies to fully evaluate the potential of vitamin C as an anticancer agent.