Rizika a nežádoucí účinky supplementace vitamínem E
Ca plic u kuřáků
- VITamins And Lifestyle (VITAL) study prospectively
- Association between long-term use of supplemental vitamins (10-year intake) and the risk of lung cancer
- In a cohort of 77,126 men and women
- No relationships were reported between intake of multivitamins, vitamin C, vitamin E, or folate and the risk of lung cancer
- Suppl. vitamin E in current but not in former smokers
- Associated with an 11% increased risk of lung cancer for every 100 mg/day increase
- Intakes greater than 215 mg/day were specifically linked to a 29% increase in risk for non-small cell lung cancer [10] !!!
Ca prostaty
- One study suggested an increased risk of prostate cancer with vitamin E supplementation [9]
- Alpha-Tocopherol, Beta-Carotene cancer (ATBC) prevention study
- Four-arm, randomized, double-blind, placebo-controlled trial
- Investigate the effect of alpha-tocopherol supplementation on lung cancer development in 29,133 male smokers
- 32% reduction in the incidence of prostate cancer in participants given daily supplements
- 50 mg of synthetic alpha-tocopherol (equivalent to 25 mg of RRR-alpha-tocopherol) alone
- Or in combination with beta-carotene
- Compared to those given beta-carotene alone or a placebo [10]
- No differences in the incidence of prostate cancer were found
- Between alpha-tocopherol recipients and nonrecipients
- During the 18-year post-intervention period [10]
- Physicians’ Health Study II (PHS II)
- Followed 14,641 healthy men aged 50 years and older
- Supplementation with 400 IU of synthetic vitamin E (equivalent to 180 mg of RRR-alpha-tocopherol) every other day for 8 years
- Had no effect on the
- Risk of prostate cancer,
- Other site-specific cancers,
- Or total cancer [10]
- Multicenter, randomized, placebo-controlled SELECT trial (SELenium and vitamin E Cancer prevention Trial)
- Supplementation of vitamin E (equivalent to 180 mg/day of RRR-alpha-tocopherol), alone or in combination with selenium
- Halted because there was no evidence of benefit in preventing prostate cancer in 35,533 healthy men aged 50 years and older
- Median of seven years’ follow-up
- Risk of prostate cancer was found to be significantly increased by 17% in participants supplemented with vitamin E alone during the trial period
- But not when vitamin E was combined with selenium — compared to placebo
- Supplemental selenium with or without vitamin E
- Was associated with a significant increase in the risk of advanced prostate cancer
- In individuals with higher versus lower selenium status
- Risks of total and advanced prostate cancer were significantly elevated with vitamin E supplementation
- In subjects with low versus high selenium status [10]
Kardiovaskulární choroby
- A meta-analysis concluded that VE supplementation (400–800 IU)
- Decreased the risk of suffering both non-fatal and fatal myocardial infarction
- Preventive effect did not appear using other antioxidants [8]
- Stroke relative risk, supplementation with VE (50–800 IU) did not seem to affect the total stroke risk [8] !!!
- It did increase the risk of hemorrhagic stroke by 22% [8] !!!
- High-dose vitamin E supplements do not protect against cardiovascular disorders [9]
- Cigarette smokers (the Alpha-Tocopherol, Beta-Carotene cancer prevention [ATBC] study
- Potentially harmful effects of supplemental vitamin E were reported on the risk of hemorrhagic stroke in the ATBC trial [10]
- Individuals at-risk of CVD (the Heart Outcomes Prevention Evaluation [HOPE]-The Ongoing Outcomes [HOPE-TOO study]
- Risk of heart failure in the HOPE and GISSI trials [10]
- Patients who have suffered a myocardial infarction (Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto miocardico-GISSI-prevenzione trial
- Risk of heart failure in the HOPE and GISSI trials [10]
- Failed to find significant CVD risk reductions with alpha-tocopherol supplementation [10]
- 3-year randomized controlled trial in 160 patients with coronary heart disease (CHD)
- Low high-density-lipoprotein (HDL) levels
- Combination of simvastatin (Zocor) and niacin
- Increased the HDL2 subfraction level (considered the most cardioprotective)
- Inhibited the progression of coronary artery stenosis (narrowing)
- Decreased the frequency of cardiovascular events
- Myocardial infarction and stroke
- When an antioxidant combination of
- In a much larger randomized controlled trial of simvastatin in more than 20,000 men and women with CHD or diabetes
- And an antioxidant combination of
- 600 mg of all-rac-alpha-tocopherol (297 mg of RRR-alpha-tocopherol)
- 250 mg of vitamin C
- 20 mg of beta-carotene daily
- Antioxidant combination did not adversely affect the cardioprotective effects of simvastatin therapy over a five-year period [10]
Krvácivost
- High doses of supplemental alpha-tocopherol may interfere with the vitamin K-dependent blood clotting cascade
- Increase the risk of bleeding in individuals taking anticoagulant drugs
- Some physicians recommend discontinuing high-dose vitamin E supplementation 2-4 weeks before elective surgery
- Including dental procedures — to decrease the risk of hemorrhage [10]
Zvýšená krváciost při současné terapii antikoagulancii / antiagregancii
Should combine alpha-tocopherol supplements without close medical supervision because of the increased risk of hemorrhage
- Heparin
- Vitamin K antagonist, warfarin (Coumadin)
- Antiplatelet drugs
- Clopidogrel (Plavix)
- Ticlopidine (Ticlid)
- Tirofiban (Aggrastat)
- Dipyridamole (Aggrenox)
- Non-steroidal anti-inflammatory drugs (NSAIDs)
- Aspirin, ibuprofen, and others
- Vitamin K deficient due to liver failure
- Propensity to bleed (e.g., bleeding peptic ulcers)
- Inherited bleeding disorders (e.g., hemophilia)
- History of hemorrhagic stroke
Potentiate the antithrombotic activity of supplemental
- Fish oils
- Garlic
- Curcumin
- Ginkgo biloba [10]
Toxicita / Předávkování
- Few side effects have been noted in adults taking supplements of less than 2,000 mg of alpha-tocopherol daily
- Natural or synthetic vitamin E [10]
- Most studies assessing safety issues or toxicity of alpha-tocopherol supplementation
- Lasted only a few weeks to a few months
- Side effects associated with long-term alpha-tocopherol supplementation have not been adequately studied [10]
Impaired blood clotting
- Most worrisome possibility
- Increases the likelihood of hemorrhage in some individuals [10]
- A meta-analysis of randomized controlled trials
- Daily vitamin E supplementation — equivalent to 25 to 536 mg/day of RRR-alpha-tocopherol — for several years
- Resulted in a significant, 10% reduction in the risk of ischemic stroke (five trials, 91,393 participants)
- Nonsignificant trend towards an increased risk of hemorrhagic stroke (five trials, 100,748 participants) [10]
Retinopatie zhoršení
- One randomized controlled trial in 601 patients
- With common forms of RP
Daily supplementation with 400 IU of all-rac-alpha-tocopherol synthetic vitamin E (equivalent to 180 mg/day of RRR-?-tocopherol)
- 180 mg of RRR-a-tocopherol
- Modestly but significantly increased the loss of retinal function [10]
- Should therefore avoid taking high-dose vitamin E supplements if they are not deficient in vitamin E [10]
Daily supplementation with 15,000 IU of vitamin A
- 4,500 µg RAE of vit. A
- Significantly slowed the loss of retinal function over a period of 4-6 let
- Patients with common forms of RP may benefit from long-term vitamin A supplementation
- But should avoid high-dose supplemental vitamin E [10]
