What do systematic reviews say?

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

Vitamin A supplementation (200,000 to 400,000 IU) vs placebo or no treatment

Vitamin A supplementation (200,000 to 400,000 IU) showed no clear difference in infant adverse effects: bulging fontanelle compared with placebo or no treatment (low certainty).

• Vitamin A supplementation for postpartum women 2016 · Cochrane Headline outcomes only
  RR 2 [0.61, 6.55]
  1 study · 444 participants
  Low

Vitamin A supplementation (200,000 to 400,000 IU) vs placebo or no treatment

Vitamin A supplementation (200,000 to 400,000 IU) showed no clear difference in maternal adverse effects after administration: abdominal pain compared with placebo or no treatment (low certainty).

• Vitamin A supplementation for postpartum women 2016 · Cochrane Headline outcomes only
  RR 1.28 [0.95, 1.73]
  1 study · 786 participants
  Low

Interventions (vitamin B1, mefenamic acid, tranexamic acid) vs placebo or active comparators (desmopressin, sodium diclofenac, flavonoids)

The review found no eligible studies for this question.

• Interventions to prevent or treat heavy menstrual bleeding or pain associated with intrauterine‐device use 2022 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

Pyridoxal 5 phosphate (vitamin B6) vs placebo

Pyridoxal 5 phosphate (vitamin B6) showed no clear difference in global: Other adverse effects than tardive dyskinesia Self‐report by… compared with placebo (low certainty).

• Pyridoxal 5 phosphate for neuroleptic‐induced tardive dyskinesia 2015 · Cochrane Headline outcomes only
  RR 3.97 [0.2, 78.59]
  2 studies · 65 participants
  Low

Vitamin A or retinoids (systemic or topical; incl. 13-cis-retinoic acid, acitretin) vs placebo or no treatment

• Interventions for treating oral leukoplakia to prevent oral cancer 2016 · Cochrane All outcomes

  4 to 12 months
  SoF 1, Safety of the intervention at 4 to 12 months: '3 studies (1 each evaluating topical acitretin, topical 13-cis-retinoic acid, 200,000 IU per week of vitamin A) found no adverse effects. Systemic 13-cis-retinoic…
  4 studies
  GRADE not reported

Provision of maize flour or maize flour products fortified with iron plus other vitamins and minerals vs unfortified maize flours or maize flour products

The review found no eligible studies for this question.

• Fortification of maize flour with iron for controlling anaemia and iron deficiency in populations 2018 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

Lutein with or without zeaxanthin vs placebo

It is very uncertain whether lutein with or without zeaxanthin 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
  OR 1.06
  Studies not reported
  Very low

Zinc vs placebo

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

Beta‐carotene vs placebo

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

High‐dose vs low‐dose coenzyme Q10 and vitamin E

• Treatment for speech disorder in Friedreich ataxia and other hereditary ataxia syndromes 2014 · Cochrane Headline outcomes only
  no estimate extracted
  1 study · 50 participants
  GRADE not reported

Intervention not reported

The intervention showed no clear difference in adverse effects: fever 48 to 72 hours (low certainty).

• Vitamin A supplementation for the prevention of morbidity and mortality in infants one to six months of age 2016 · Cochrane Headline outcomes only
  RR 0.94 [0.83, 1.07]
  3 studies · 3187 participants
  Low

Intervention not reported

The intervention showed no clear difference in adverse effects: vomiting 48 to 72 hours (low certainty).

• Vitamin A supplementation for the prevention of morbidity and mortality in infants one to six months of age 2016 · Cochrane Headline outcomes only
  RR 0.95 [0.67, 1.35]
  2 studies · 2187 participants
  Low

Intervention not reported

The intervention showed no clear difference in adverse effects: diarrhoea 48 to 72 hours (low certainty).

• Vitamin A supplementation for the prevention of morbidity and mortality in infants one to six months of age 2016 · Cochrane Headline outcomes only
  RR 1.07 [0.82, 1.4]
  3 studies · 2176 participants
  Low

Rice fortified with iron alone or in combination with other micronutrients vs unfortified rice (no micronutrients added)

Rice fortified with iron alone or in combination with other… may leads to higher any adverse effects (hookworm infection risk) compared with unfortified rice (no micronutrients added) (low certainty).

• Fortification of rice with vitamins and minerals for addressing micronutrient malnutrition 2019 · Cochrane Headline outcomes only
  RR 1.78 [1.18, 2.7]
  1 study · 785 participants
  Low

Intervention not reported

The intervention leads to higher adverse effects: bulging fontanelle within 48 to 72 hours (high certainty).

• Vitamin A supplementation for the prevention of morbidity and mortality in infants one to six months of age 2016 · Cochrane Headline outcomes only
  RR 3.1 [1.89, 5.09]
  9 studies · 13493 participants
  High