FoundMyFitness · 2020-05-13 · Rhonda Patrick (host)
Vitamin C: Oral vs. Intravenous, Immune Effects, Cancer, Exercise Adaptation & More
75 claims checked against research: 4 contradicted 4 overstated 7 needing context 50 supported 10 unverified
4 Overstated
A randomized controlled trial in 20 athletes found that supplementing with 250 mg of vitamin E, 15 mg of beta-carotene, and 1 g of vitamin C increased the activity of catalase, SOD, glutathione peroxidase, and glutathione reductase in neutrophils.
"For example, a randomized controlled study in 20 athletes in their early 20s who participated in duathlon-like competitions found that antioxidant supplementation increased the antioxidant defenses of neutrophils. The athletes took either an antioxidant cocktail consisting of 250 milligrams of vitamin E and 15 milligrams of beta-carotene or a placebo every day for 90 days. During the final 15 days of the study, the athletes took an additional supplement of 1 gram of vitamin C or a placebo. At the end of the study period, plasma antioxidant concentrations were considerably higher among the supplemented group than those of the placebo group. The activity of catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase in the supplemented group's neutrophils increased, too" (said at 0:44:05)
A randomized controlled trial investigated the effects of 90 days of antioxidant supplementation on neutrophil antioxidant defenses in athletes (PMID 11889577). However, the study administered 500 mg/day of vitamin E and 30 mg/day of beta-carotene (with 1 g/day of vitamin C added during the final 15 days), rather than 250 mg of vitamin E and 15 mg of beta-carotene. Furthermore, while the trial analyzed catalase, superoxide dismutase (SOD), glutathione peroxidase, and glutathione reductase, supplementation significantly increased the enzymatic activities of superoxide dismutase and catalase, not glutathione peroxidase or glutathione reductase.
In a 10-year study of nearly 5,400 participants aged 55 and older, every 54-milligram increase in daily dietary vitamin C intake was associated with an 18% reduction in the risk of Alzheimer's disease, and a 35% reduction in smokers.
"A 10-year-long study involving nearly 5,400 participants who were at least 55 years of age looked at whether dietary intake of antioxidants was related to the risk of developing Alzheimer's disease... For every 54-milligram increase in vitamin C intake, there was an 18% reduction in the risk of Alzheimer's disease. In smokers, the protective effect of vitamin C was even more robust, with a 35% decrease in Alzheimer's disease risk for every 54-milligram increase." (said at 0:49:43)
The cited figures (an 18% risk reduction overall and a 35% reduction among smokers in a cohort of 5,395 participants aged 55 and older) come from the Rotterdam Study published in 2002 after a mean follow-up of 6 years. However, in the subsequent 9.6-year follow-up of this exact same cohort published in 2010, dietary vitamin C intake was no longer significantly associated with a reduced risk of Alzheimer's disease or dementia after multivariate adjustment (P > .99 for trend).
- supports: Dietary intake of antioxidants and risk of Alzheimer disease. (JAMA 2002) · cited 1078x in the literature
"After a mean follow-up of 6 years, 197 participants developed dementia, of whom 146 had Alzheimer disease. When adjustments were made for age, sex, baseline Mini-Mental State Examination score, alcohol intake, education, smoking habits, pack-years of smoking, body mass index, total energy intake, presence of carotid plaques, and use of antioxidative supplements, high intake of vitamin C and vitamin E was associated with lower risk of Alzheimer disease (rate ratios [RRs] per 1-SD increase in intake were 0.82 [95% confidence interval [CI], 0.68-0.99] and 0.82 [95% CI, 0.66-1.00], respectively). Among current smokers, this relationship was most pronounced (RRs, 0.65 [95% CI, 0.37-1.14] and 0.58 [95% CI, 0.30-1.12], respectively)" (abstract, results, passage verified)
pubmedfull study (doi) - contradicts: Dietary antioxidants and long-term risk of dementia. (Archives of neurology 2010) · cited 276x in the literature
"During a mean follow-up period of 9.6 years, dementia developed in 465 participants, of whom 365 were diagnosed as having AD... Dietary intake levels of vitamin C, beta carotene, and flavonoids were not associated with dementia risk after multivariate adjustment (P > .99 for trend for vitamin C and beta carotene and P = .60 for trend for flavonoids). Results were similar when risk for AD was specifically assessed." (abstract, results, passage verified)
pubmedfull study (doi)
A retrospective study in patients with mononucleosis found that intravenous vitamin C reduced viral titers and replication, and decreased antibody levels by 42%.
"As far as mononucleosis goes, a retrospective study found that patients with mono who were given intravenous vitamin C showed decreased viral titers and replication, but their antibody levels decreased 42%, probably due to the reduced viral replication." (said at 0:51:48)
A retrospective study from the Riordan Clinic database (Mikirova and Hunninghake, 2014) evaluated patients with Epstein-Barr virus (EBV) infection, mononucleosis, and chronic fatigue syndrome receiving intravenous vitamin C, finding reductions in EBV antibody levels (EBV EA IgG and EBV VCA IgM) over time. However, the study was an uncontrolled retrospective chart review and did not directly measure viral titers or viral replication in patients; the idea that ascorbate suppresses viral replication was an inference drawn from prior in vitro literature. Claiming the clinical study demonstrated reductions in viral titers and replication overstates what was directly measured.
A meta-analysis found that intravenous vitamin C combined with conventional therapy is more effective than conventional therapy alone for treating viral myocarditis in children.
"A really large meta-analysis found that intravenous vitamin C combined with conventional therapy is better than conventional therapy alone for the treatment of viral myocarditis in children." (said at 0:52:18)
A systematic review and meta-analysis concluded that intravenous vitamin C combined with conventional therapy was more effective than conventional therapy alone for pediatric viral myocarditis, showing higher clinical effective rates and lower cardiac enzyme levels (LDH, CK, and CK-MB). However, characterizing this as a 'really large meta-analysis' overstates the size and strength of the evidence: the analysis included only 8 studies comprising a total of 789 children (426 treatment, 363 control). The overall evidence certainty is low due to small trial sample sizes and methodological limitations in the underlying literature.
Unverified means no publication matching the claim was located; it does not prove the claim false. Spotted an error? See the corrections policy - disputes from the people quoted are prioritized.