What do systematic reviews say?

Vitamin E vs placebo

It is very uncertain whether vitamin E changes adverse effects compared with placebo (very low certainty).

• Antioxidant vitamin and mineral supplements for slowing the progression of age‐related macular degeneration 2023 · Cochrane Headline outcomes only
  no estimate extracted
  4 participants
  Very low

Vitamin E vs placebo

• Antioxidant vitamin and mineral supplements for preventing age‐related macular degeneration 2017 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  Low

Vitamin E + vitamin C vs placebo

Vitamin C and vitamin E showed no clear difference in any adverse effects of vitamin supplementation sufficient to stop… compared with placebo (moderate certainty).

• Vitamin supplementation for preventing miscarriage 2016 · Cochrane Headline outcomes only
  RR 1.16 [0.39, 3.41]
  1 study · 739 participants
  Moderate

Vitamin C 1400 mg plus vitamin E 800 mg vs placebo

It is very uncertain whether vitamin C 1400 mg plus vitamin E 800 mg changes adverse effects compared with placebo (very low certainty).

• Antioxidant supplementation for sickle cell disease 2024 · Cochrane Headline outcomes only
  RR 0.56 [0.31, 1]
  1 study · 83 participants
  Very low

Vitamin C vs placebo

The review found no eligible studies for this question.

• Vitamin C supplementation for prevention and treatment of pneumonia 2021 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

Vitamin C vs placebo

The review found no eligible studies for this question.

• Antioxidant vitamin and mineral supplements for preventing age‐related macular degeneration 2017 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

Multivitamin vs placebo

• Antioxidant vitamin and mineral supplements for preventing age‐related macular degeneration 2017 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  Moderate

Staple foods fortified with vitamin A vs same unfortified staple foods

The review found no eligible studies for this question.

• Fortification of staple foods with vitamin A for vitamin A deficiency 2019 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

Staple food fortified with vitamin A plus other micronutrients vs no intervention

The review found no eligible studies for this question.

• Fortification of staple foods with vitamin A for vitamin A deficiency 2019 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

Staple food fortified with vitamin A plus other micronutrients vs same unfortified staple foods

The review found no eligible studies for this question.

• Fortification of staple foods with vitamin A for vitamin A deficiency 2019 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

Vitamin D given to infants vs placebo or no treatment

Vitamin D given to infants showed no clear difference in adverse effects (hypercalcaemia) compared with placebo or no treatment (low certainty).

• Vitamin D supplementation for term breastfed infants to prevent vitamin D deficiency and improve bone health 2020 · Cochrane Headline outcomes only
  RR 1.45 [0.54, 3.86]
  1 study · 98 participants
  Low

Vitamin C vs placebo

It is very uncertain whether vitamin C changes adverse effects (urticaria) Defined as participants reporting… compared with placebo (very low certainty).

• Vitamin C supplementation for prevention and treatment of pneumonia 2021 · Cochrane Headline outcomes only
  RR 3.11 [0.13, 76.03]
  1 study · 674 participants
  Very low

Vitamin D given to lactating mothers vs placebo or no treatment

Vitamin D given to lactating mothers showed no clear difference in adverse effects (hypercalcaemia) compared with placebo or no treatment (low certainty).

• Vitamin D supplementation for term breastfed infants to prevent vitamin D deficiency and improve bone health 2020 · Cochrane Headline outcomes only
  RR 1.31 [0.51, 3.32]
  3 studies · 557 participants
  Low

Vitamin A and fish oils (docosahexaenoic acid) vs placebo, vitamins, or no treatment

• Vitamin A and fish oils for preventing the progression of retinitis pigmentosa 2020 · Cochrane Headline outcomes only
  no estimate extracted
  4 studies · 944 participants
  Very low

Antioxidant multivitamin and mineral supplement vs placebo or no treatment

Antioxidant multivitamin and mineral supplement may leads to lower adverse effects compared with placebo or no treatment (low certainty).

• Antioxidant vitamin and mineral supplements for slowing the progression of age‐related macular degeneration 2023 · Cochrane Headline outcomes only
  OR 0.87
  0 participants
  Low

Vitamin A plus iron plus folate vs iron plus folate

The review found no eligible studies for this question.

• Vitamin supplementation for preventing miscarriage 2016 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

Multivitamin plus iron plus folate vs iron plus folate

The review found no eligible studies for this question.

• Vitamin supplementation for preventing miscarriage 2016 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

LongoVital (herbal plus vitamin component) vs LongoVital (herbal component alone)

• Systemic interventions for recurrent aphthous stomatitis (mouth ulcers) 2012 · Cochrane All outcomes

  4 months
  Reported adverse events were minor and evenly distributed between the groups (Kolseth 2005).
  1 study · 40 participants
  GRADE not reported

LongoVital (herbal plus vitamin component) vs placebo

• Systemic interventions for recurrent aphthous stomatitis (mouth ulcers) 2012 · Cochrane All outcomes

  4 months
  Reported adverse events were minor and evenly distributed between the groups.
  1 study · 40 participants
  GRADE not reported

Vitamin B12 (sublingual, 1000 mcg daily for 6 months) vs placebo

• Systemic interventions for recurrent aphthous stomatitis (mouth ulcers) 2012 · Cochrane All outcomes

  6 months
  No adverse events were associated with receiving vitamin B12 or placebo in this study.
  1 study · 58 participants
  GRADE not reported