Vitamin C in pregnancy: evidence and safety

How does vitamin C work?

Humans, unlike most animals, cannot synthesize vitamin C, which is what makes it an essential part of the diet rather than something the body produces on demand. NIH ODS describes it as required for the biosynthesis of collagen, L-carnitine, and certain neurotransmitters, with a further role in protein metabolism. It acts as an important physiological antioxidant and regenerates other antioxidants inside the body, including alpha-tocopherol, which is vitamin E. It also has a role in immune function and improves the absorption of nonheme iron, the pairing that puts vitamin C next to iron in a prenatal.

What does the evidence say about vitamin C in pregnancy?

• The recommended amount of vitamin C in pregnancy is 85 mg a day (80 mg for ages 14 to 18), with an upper limit of 2,000 mg a day. 1
• Vitamin C helps your body make collagen, recover from wounds, and absorb iron, which is why it's often paired with iron in prenatal vitamins. 1
• Getting enough vitamin C supports normal immune function, though taking extra on top of that hasn't shown a consistent pregnancy-specific benefit against colds or respiratory infections. 2
• Taking more than the upper limit can cause diarrhea, nausea, and stomach discomfort. 1
• Pregnancy Smart's Immune & Respiratory Support formula lists vitamin C (ascorbic acid) at 750 mg per three-capsule serving. 3

What's on the label?

Absorption is why the big numbers on a label stop scaling. NIH ODS puts uptake at roughly 70 to 90 percent at moderate intakes of 30 to 180 mg a day, falling below 50 percent above 1 gram a day, with the unmetabolized ascorbic acid excreted in urine. On form, ascorbic acid is the most common and has bioavailability equivalent to the ascorbic acid naturally present in food. ODS concludes that simple ascorbic acid is the preferred source of supplemental vitamin C over sodium ascorbate, calcium ascorbate, other mineral ascorbates, or ascorbic acid with bioflavonoids.

• Immune and Respiratory Support lists Vitamin C at 750 mg per serving, as printed on the Supplement Facts panel.

When comparing any brand, read the Supplement Facts panel for the exact per-serving amount and look for third-party test results. Add any prenatal-vitamin amount of the same ingredient to your daily total before comparing against a pregnancy upper limit.

What should I know before taking vitamin C?

Please consult your healthcare provider before adding this supplement to a prenatal regimen, particularly if you are on prescription medication or have a scheduled procedure. Supplement contents are not FDA-verified, so a labeled dose and an actual dose can differ; look for third-party-tested brands.