TABLE 1.
Summary of BM nutrients1
| Infant reliance on BM | Concentrations trend | Affected by maternal status | Affected by maternal diet | Affected by maternal supplementation | Maternal factors influencing BM concentrations | Comments | |
|---|---|---|---|---|---|---|---|
| Thiamin | + | Increases over first several months | − | + | +/− (+ in case of maternal dietary insufficiency) | Insufficient data | The body does not store thiamin so continuous supply is needed to mother and infant |
| Riboflavin | + | Decreases vs. stable | +/− (mixed evidence) | + | + | Insufficient data | Very limited infant reserves at birth |
| Vitamin B-6 | +/− | Increases during first weeks postpartum, followed by gradual decline | + | + | + | Insufficient data | Gestational reserves help support infant vitamin B-6 needs through first months of lactation; after 6 mo, BM alone may be insufficient to meet infant needs (1) |
| Vitamin B-12 | + | Decreases during first 3–4 mo of lactation | + | + | +/− | Veganism/vegetarianism/low consumption of animal source foods (−), pernicious anemia (−) | Limited infant reserves at birth |
| Folate | + | Peaks at 2–3 mo of lactation | − | − | − | Insufficient data | Supplemental folate may affect BM folate concentrations in undernourished women (2); more data are needed; only severe maternal deficiency compromises BM concentrations |
| Choline | + | Increases rapidly from 7 to 22 d postpartum and remains stable in mature milk | + | + | + | SNPs in MTHFR (−), preterm delivery (−), inflammation (+), hormones (+/−) | Gene polymorphisms may explain variation in BM choline concentrations in women with similar intakes (3) |
| Vitamin C | + | Highest in colostrum, decreases with progression of lactation | − | +/− | +/− | Preterm delivery (+), smoking (−), diabetes (−) | Greater effect of diet and supplementation in women with poor status; the body does not store vitamin C so continuous supply is needed to mother and infant |
| Vitamin A | + | Highest in colostrum, stabilizes in mature milk | − (unless maternal reserves are depleted) | +/− (+ if maternal reserves are inadequate) | + | Preterm delivery (−), adolescence (−), parity (+) | BM vitamin A derived from circulating as well as dietary retinol (4) |
| Vitamin D | +/− [vitamin D3, but not active 25(OH)D] | Little 25(OH)D in BM | +/− (conflicting data) | +/− [diet may affect BM vitamin D3, but not active 25(OH)D] | + | Season, sun exposure (+), obesity (−) | Primary form passed from maternal circulation to BM is vitamin D3, the biological precursor of 25(OH)D (5, 6) |
| Vitamin E | + | Decreases from colostrum to mature milk, then stable | − | − | + | Preterm delivery (−) | Limited infant reserves at birth; Greater increase in BM vitamin E concentrations with natural (RRR-α-tocopherol) vs. synthetic all-rac-α-tocopherol) supplementation (7) |
| Vitamin K | — | Low concentrations in BM | − | − | + | Insufficient data | — |
| Iron | — | Low concentrations in BM, declines through first year of lactation | − | − | − | No consistent evidence | Infants depend on hepatic reserves to meet iron needs (8) |
| Copper | — | Low concentrations in BM, declines as lactation progresses | − | − | − | BM selenium concentrations (+) | Hepatic reserves protect infants from deficiency in early infancy (9) |
| Zinc | +/− (+ in early lactation) | Sharp initial decrease followed by gradual decline | − | − | − | Age (−), parity (−), iron deficiency (−) | Infant zinc stores are limited (9) |
| Calcium | + | Increases in first week, subsequent gradual decline for duration of lactation | − | +/− (+ where habitual calcium intake is low) | − | Adolescence (−), iron deficiency anemia (−) | — |
| Phosphorus | + | Increases in first week, subsequent gradual decline for duration of lactation | +/− (+ only in case of genetic anomalies) | − | No data | Familial hypophosphatemia (−), hyperparathyroidism (−) | BM phosphorus is tightly regulated (10) |
| Magnesium | + | Stable during lactation | − | − | − | Adolescence (−) | — |
| Iodine | + | Initial decline, stable after 1 mo | − | + | + | Smoking (−) | Influenced by environment (soil iodine, salt iodization, etc.); infants are born with limited reserves |
| Selenium | + | Decreases throughout lactation | +/− (weak correlation, if present) | + | + | No consistent evidence | Influenced by environment (soil selenium); infants are born with limited reserves |
| Protein | + | Brief, sharp decrease, then stable from 2 to 6 mo until weaning | − | +/− (amino acid composition varies by maternal intake) | N/A | Milk volume (−) | Similar concentrations in BM of well-nourished and undernourished mothers |
| Lipids | + | Sharp increase in first week, then stable | + | +/− (FA composition varies by maternal intake) | N/A | %IBW (+), milk volume (−) | Large intraindividual CV |
| Carbohydrates | + | Lactose is lowest in colostrum, stabilizes as milk matures | − | − | N/A | BMI (−), milk volume (+), preterm delivery (−) | Non-nutritive HMOs decrease from colostrum to mature milk |
1BM, breast milk; HMO, human-milk oligosaccharide; IBW, ideal body weight; MTHFR, methylenetetrahydrofolate reductase; N/A, Not available; SNP, single nucleotide polymorphism; 25(OH)D, 25-hydroxyvitamin D; +, Yes; −, No.