Vitamin C | Memorial Sloan Kettering Most cancers Middle
Vitamin C, also called ascorbic acid, exists as both ascorbic acid or ascorbate. It’s a water-soluble vitamin that’s discovered in lots of recent vegetables and fruit, and is crucial for quite a lot of physiologic features together with formation of collagen and catecholamines, and carnitine and peptide synthesis (1). It’s not synthesized within the human physique, and deficiency could cause scurvy. Oral vitamin C is consumed as an antioxidant complement for immune safety towards colds and the flu, wound therapeutic, cardiovascular well being, and most cancers prevention. Excessive-dose intravenous (IV) vitamin C is being studied as a most cancers therapy.
Vitamin C has been investigated in lots of scientific and epidemiologic research. Common consumption of vitamin C dietary supplements might scale back length and severity of the frequent chilly. Nonetheless, the impact is minimal besides in individuals uncovered to acute extreme bodily stress (2). In sufferers with septic shock, vitamin C mixed with corticosteroids and thiamine didn’t defend towards organ harm (85). However in adults present process oral surgical procedure, vitamin C decreased postoperative ache with out elevated side-effects (72). It’s also believed to advertise cardiovascular well being however findings are inconsistent. Earlier research counsel that dietary vitamin C, however not dietary supplements, might scale back the danger of coronary coronary heart ailments (3). Nonetheless, two large-scale randomized trials didn’t discover any advantages (4) (5). Additional, supplementation with nutritional vitamins C and E elevated threat of mortality and nonfatal myocardial infarction in sufferers with coronary artery illness (6). Information of vitamin C’s results in lowering blood stress are conflicting as nicely (7) (8). Extra research don’t assist prophylactic vitamin C to decrease postoperative atrial fibrillation incidence amongst cardiac surgical procedure sufferers (69) (70), however conflicting information present a discount in different post-surgical uncomfortable side effects (71), and a scientific overview reported reductions within the size of hospital keep, length of mechanical air flow, and decreased incidence of atrial fibrillation (80).
In a examine of sufferers with sepsis and acute respiratory misery syndrome (ARDS), intravenous vitamin C had no important impact on organ dysfunction or inflammatory markers (84), however it could assist forestall postoperative pulmonary issues in low-risk cardiac surgical procedure sufferers (86); enhance ventricular perform in sufferers present process coronary artery bypass grafting together with lowering the size of ICU keep (87); in addition to decrease oxidative imbalance and vascular reworking brought on by psychological stress (88).
Vitamin C supplementation might scale back blood glucose and lipids in sort 2 diabetes sufferers (9). It additionally decreases urinary an infection charges in pregnant girls (10); lowers incidence of organ failure and shortens ICU keep after surgical procedure (11); and protects towards Alzheimer’s illness (12) (13). Vitamin C may help eradicate H. pylori an infection when added to a typical remedy routine (14) and supplementation might potentiate therapy efficacy in some sufferers with thalassemia (68). Nonetheless, antioxidants together with vitamin C don’t forestall or gradual the development of age-related cataracts (15) or macular degeneration (16). Vitamin C may scale back endurance coaching effectivity (17).
The function of vitamin C in most cancers prevention shouldn’t be definitive. Conclusions of a scientific overview counsel its security (81) and one other examine confirmed its skill to scale back oxidative stress (18). Additional, excessive plasma ranges of vitamin C have been related to decrease gastrointestinal most cancers incidence most likely because of its protecting results towards dietary carcinogenic nitroso compounds (19). Consumption of nutritional vitamins A, C, or E decreased the danger of cervical most cancers (20), however they didn’t forestall gastrointestinal (21), prostate (22), lung cancers (23) , or different most cancers incidences, or have an effect on most cancers mortality (24) (73). As well as, vitamin C supplementation was related to elevated threat of liver most cancers, though this impact was not noticed with vitamin C from dietary sources (25).
Excessive-dose vitamin C has been lengthy been used instead most cancers therapy (26) based mostly on the speculation that the formation of latest collagen resists malignant infiltration (27). Early experiences utilizing parenteral plus oral ascorbic acid confirmed promising outcomes (28), however subsequent randomized placebo-controlled trials in superior most cancers sufferers utilizing 10 g per day of oral vitamin C didn’t show important advantages (29) (30). This lack of impact is defined by the discovering of a pharmacokinetic examine that ascorbic acid can solely attain a restricted plasma focus via oral administration (31). The next pharmacologic focus, achieved solely through intravenous injection, had selective cytotoxic results on most cancers cell traces (32) (33). Ascorbic acid is postulated to behave as a provider of hydrogen peroxide to the extracelluar fluid (32) the place it generates free radicals towards tumor cells (33). Excessive-dose IV ascorbic acid as much as 1.5 g /kg/day (34), or used with chemotherapy (74) seems to be well-tolerated. It could enhance the standard of lifetime of terminal most cancers sufferers (35), and scale back chemotherapy-associated toxicity (67). This led to a renewed curiosity in finding out high-dose IV vitamin C as an anticancer therapy (34) (36). Nonetheless, it must be thought to be an investigational drug and used solely in a scientific trial setting.
There are conflicting theories towards the usage of vitamin C dietary supplements throughout chemotherapy. Preclinical research discovered that most cancers cells preferentially uptake vitamin C (37) and render some chemotherapy medicine much less efficient (38). Additionally, a serious concern surrounding the usage of antioxidants reminiscent of vitamin C is that they will intrude with the actions of chemotherapy and radiation remedy that depend on the manufacturing of reactive oxygen species for his or her cytotoxic actions (39). Nonetheless, a scientific examine confirmed that ascorbic acid doesn’t scale back the therapeutic results of paclitaxel and carboplatin (40). One other examine discovered a rise in chemotherapy-associated opposed results with insufficient consumption of vitamin C in kids with acute lymphoblastic leukemia (41). Preliminary findings point out that short-term vitamin C plus E supplementation throughout radiotherapy had a protecting impact towards xerostomia in sufferers with head and neck most cancers (75); a mixture of nutritional vitamins C, E, and selenium lowered radioiodine-induced oxidative stress in thyroid most cancers sufferers (76); and supplementation might improve the organic results of DNA methyl transferase inhibitors in sufferers with myeloid most cancers (89).
Adversarial results from vitamin C are uncommon however there are experiences of gastrointestinal upset, kidney stone formation (42) , and hemolytic anemia in sufferers with G6PDH deficiency (43) (44). Sufferers with a historical past of oxalate kidney stones, renal insufficiency, hematochromatosis, or these present process chemotherapy ought to seek the advice of their physicians earlier than taking vitamin C dietary supplements.