HUMAN MILK

HUMAN MILK

Constituents

Nutrient composition

Nitrogen retention (mg/kg/day) The nutrient compositions of pre-

term and term human milk are dis- played in Box 1.3.1. There was no information located about stratifi-

cation by gestational age or birth

Energy intake (kcal/kg/day)

weight. Also, no information was located which described the nutrient

content of the milk of mothers who delivered infant can reduce some of this solute load. The

SGA infants.

estimated renal solute load (ERSL) takes into Breastmilk meets almost all these require- account the growth of the infant and can be

ments. There may be specific need of addi- calculated as the potential renal solute load

tional minerals and vitamins for breastfed minus 90% of the weight gain in grams (ERSL

LBW infants during certain periods of life. For = PRSL – [0.9 x weight gain in grams]) (42).

instance, pre-term infants of <32 weeks gesta- tion need additional phosphorus, calcium and

vitamin D from the time feeding is established Recommended nutrient intakes (RNIs) for

1.2 Nutritional requirements

until they reach term post-menstrual age. It pre-term and SGA infants have been published

should be noted that breastmilk has great vari- by a number of groups (43–45). The RNIs have

ability in composition as seen from the stand- been developed by calculating nutrient intakes

ard deviations (Box 1.3.1). In general, if the that approximate the rate of growth for a nor-

breastmilk volume is high, the concentration mal fetus of the same gestational age without

of nutrients will be lower. inducing metabolic stress; factorial equations;

provision of idealized nutrient requirements

Anti-infective constituents

and measurement of utilization and excretion. Term and pre-term human milk contains live Published nutrient requirements for pre-term

cells (macrophages, polymorphonuclear leu- infants are shown in Box 1.2.1.

cocytes, T and B lymphocytes) and a range of Although the published RNIs provide some

antimicrobial factors (secretory IgA, lactofer- indications, they cannot be used as the only

rin, lysozyme, B 12 and folate-binding proteins, basis of guidelines for feeding the LBW infant.

complement, fibronectin, mucin, and antiviral This is because outcomes vary widely accord-

factors) (47). Human milk cells and antimi- ing to the basic substrate provided. In par-

crobial factors play a major role in conferring ticular, the absorption and bioavailability of

local immunological protection to the infant’s nutrients in different types of milk vary widely

gastrointestinal tract (47, 48). Enzymes, anti- (43–44). This is particularly important for

oxidants, and cellular components in human human milk. Bioavailability of many nutrients

milk all improve the host defence of the LBW is higher from human milk than from infant

infant (49).

14 OPTIMAL FEEDING OF LOW-BIRTH-WEIGHT INFANTS: TECHNICAL REVIEW

BOX 1.2.1 Recommended daily nutrient intakes for pre-term infants >1000 g at birth

Period after birth; RNI per day

Term to

to 7 days

(stabilization to term)

1 year of age

Macronutrients

Energy, kJ/kg (kcal/kg)

417–501 (100–120) Protein, g/kg

2.2 Fat, g/kg

4.4–7.3 Carbohydrate, g/kg

Calcium, mmol/kg

6.3 mmol/d (breast fed)

9.4 mmol/d (formula fed) Phosphorus, mmol/kg

3.4 mmol/d (breast fed)

8.8 mmol/d (formula fed) Magnesium, mmol/kg

0.20–0.40 a 0.20–0.60 a Sodium, b mmol/kg

2.0–3.0 Chloride, b mmol/kg

2.0–3.0 Potassium, mmol/kg

2.5–3.5 Iron, mg/kg

0 2.0–3.0 c 2.0–3.0 c Zinc, µmol/kg

15.0 (estimate) Copper, µmol/kg

1. 1–1.9 Selenium, µmol/kg

0.04–0.06 Chromium, nmol/kg

1.0–1.9 Manganese, nmol/kg

10–20 Molybdenum, nmol/kg

2.0–4.0 Iodine, µmol/kg

Vitamin A, IU/kg

600–1400 Vitamin E, IU/kg

6–12 Vitamin K, µg/kg

8–10 Vitamin D, lU

400 Vitamin C, mg/kg

400 (800 d )

20 Vitamin B 1 , mg/kg

0.05 Vitamin B 2 , mg/kg

0.05 Vitamin B 6 , mg/g of protein intake

0.015 Vitamin B 12 , µg

0.15 0.15 0.15 Niacin, NE e /5000 U

8.6 8.6 8.6 Folate, µg

50 50 25 Biotin, µg/kg

1.5 1.5 1.5 Pantothenic acid, mg/kg

0.8–1.3 a Amount required is higher if milk from the premature infant’s mother is fortified with other minerals that may diminish the bioavailability and absorption of magnesium.

b In specific clinical situations, sodium and chlorine may need to be omitted for short periods. c From 6 wk after birth.

d Amount may be increased in particular clinical syndromes. e NE = niacin equivalents.

Adapted from reference number 43.

RESULTS

BOX 1.3.1 Concentration of nutrients in transitional and mature pre-term human milk compared with mature term milk

Component (unit/L)

Pre-term transitional

Pre-term stable

Term mature

640 ± 80 Protein, g/L

Energy, kcal/L

660 ± 60

690 ± 50

12 ± 1.5 Fat, g/L

19 ± 0.5

15 ± 1

34 ± 4 Carbohydrate, g/L

Calcium, mmol/L

6.5 ± 1.5 Phosphorus, mmol/L

8.0 ± 1.8

7.2 ± 1.3

4.8 ± 0.8 Magnesium, mmol/L

4.9 ± 1.4

3.0 ± 0.8

1.3 ± 0.3 Sodium, mmol/L

1.1 ± 0.2

1.0 ± 0.3

9.0 ± 4.1 Chloride, mmol/L

11.6 ± 6.0

8.8 ± 2.0

12.8 ± 1.5 Potassium, mmol/L

21.3 ± 3.5

14.8 ± 2.1

13.9 ± 2.0 Iron, mmol/L

13.5 ± 2.2

12.5 ± 3.2

23 22 22 Iron, mg/L

0.4 0.4 0.4 Zinc, µmol/L

15 – 46 Copper, µmol/L

58 ± 13

33 ± 14

3.2–6.3 Manganese, nmol/kg

9.2 ± 2.1

8.0 ± 3.1

3–6 Iodine, µmol/L

6 ± 8.9

7.3 ± 6.6

1.25 — Iodine, µg/L

70

Vitamins

600–2,000 Vitamin E, mg/L

Vitamin A, IU/L

500–4000

500–4000

2–3 Vitamin K, µg/L

2.9–14.5

2.9–14.5

1.2–9.2 Vitamin D, IU

Vitamin D, µg/L

0.01 0.01 0.01 Vitamin B 2 , mg/L

— Folate, mg/L

0.055 mg/418 kj

0.055 mg/418 kj

33 33 1.8 Values are mean ± SD.

From: Reference number 46