Vitamin C

Ascorbic acid and its calcium and sodium salts have the activity of vitamin C, an essential water-soluble vitamin, necessary for the normal functioning of the body. It is not produced or accumulated in the body (it is eliminated by the kidney) and must be ingested with the diet; it is very abundant in fruits and vegetables. It has antioxidant properties, improves iron absorption, keeps tissues, collagen, cartilage, bones, teeth and gums healthy, and is necessary for wound healing and immune system functioning. ^{(MedlinePlus 2019, Castro 2019)}

Breast milk contains controlled levels between 50 and 100 mg/L according to the amount of vitamin C in the diet ^{(Sauberan 2019, Tawfeek 2002)}. Levels are slightly higher in colostrum ^{(Ahmed 2011)} and in the milk of premature mothers ^{(Udipi 1985)} and decrease slightly throughout lactation. ^{(Karra 1986)}

Breast milk from malnourished mothers has levels below 50 mg/L that improve with supplements of 100 to 200 mg/day ^{(Daneel 2005, Bates 1983)}. In well-nourished mothers, supplements hardly modify vitamin C levels. ^{(Sauberan 2019, Daneel 2005, Thomas 1980 and 1979, Munks 1947)}

The relationship between vitamin C intake and breast milk levels is not well clarified ^{(Keikha 2021)}. Excessive intakes of vitamin C (even above 1,000 mg per day) do little to increase the levels in breast milk. ^{(Byerley 1985, Anderson 1985, Sneed 1981)}

There are lower levels of vitamin C in the milk of women who smoke or have diabetes. ^{(Heinz 1987)}

The daily needs of the nursing mother are 100 to 120 mg per day ^{(NIH 2021, MedlinePlus 2019, Ares 2015, Hall 2010)}. Needs in children younger than 6 months are 40 mg per day. ^{(NIH 2021, MedlinePlus 2019)}

Except in malnourished mothers and/or smokers, with a varied and balanced diet, no vitamin C supplements are needed. ^{(Ares 2015)}

The freezing ^{(Buss 2001, Bank 1985)} and pasteurization ^{(Castro 2019)} of breast milk variably decrease vitamin C levels, which can result in low plasma levels of vitamin C in premature infants fed with pasteurized bank milk who do not receive vitamin C supplements. ^{(Castro 2021 and 2019, Heinonen 1986)}

Increased concentration of vitamin C in breast milk could prevent the risk of atopy in infants. ^{(Hoppu 2005)}

The use of excessive amounts of vitamin C intravenously should be avoided in mothers with renal impairment, a history of kidney stones, G6PD deficiency or paroxysmal nocturnal hematuria, as well as in mothers of infants with kidney problems or G6PD deficiency. ^{(Khoshnam 2019, Quinn 2017, Huang 2014, Rees 1993)}

List of essential medicines WHO: compatible with breastfeeding. ^{(WHO 2002).}