Infant feeding and nutrition effects
For the first few months, the babies are fed only one food, so its composition is much more critical than the compositions of the many different foods in a mixed diet.
Babies cannot eat ordinary adult food.
Breast and bottle feed
For the first 4-6 months of life the infant should be fed either by breast feeding or on a formula based on cows’ milk modified to make its composition suitable for infants—that is, more like breast milk.
Advantages of breast feeding
Research about human milk
Docosahexaenoic acid (DHA)
- Breast feeding is natural.
- Breast milk is microbiologically clean.
- Breast milk’s nutrient composition is the standard against which infant formulas for bottle feeding must be judged.
- Only breast milk provides a complex range of anti-infective components: macrophages, lymphocytes, immunoglobulins (especially IgA), lactoferrin, lysozyme, complement, interferon, oligosaccharides (for example, bifidus factor), sialic acid, xanthine oxidase, gangliosides, glycoconjugates, growth factors, and enzymes.
- Breast feeding reduces the risk of gastrointestinal, respiratory and other infections (otitis media, meningitis, urinary tract infections), SIDS, childhood lymphomas, early allergic diseases,and type 1 diabetes.
- For most women breast feeding is a satisfying, convenient and enjoyable experience that is beneficial to the mother-child relationship.
- Mothers’ milk is always at the right temperature.
- A mother can always change from breast to bottle feeding but not the other way round.
The brain of the baby grows rapidly in infancy, from 350 g at birth to 1000 g at 12 months.
Sixty per cent of its solids are lipids and two very long chain polyunsaturated fatty acids are more abundant here and in the photoreceptors of the retina than elsewhere—DHA and AA.
DHA is present in human, not in cows’ milk. It is synthesised in the body from alpha-linolenic but probably not fast enough for the brain’s requirements especially in premature babies. Young infants fed on standard formulas had lower DHA concentration in red cells and brain (SIDS post-mortem) than breast fed infants
Lactose is not the only sugar in human milk. The concentration of oligosaccharides is higher than the protein.
Over 100 of these oligosaccharides have been chemically defined—all made up of five monosaccharides: fucose, galactose, glucose, N-acetylglucosamine, and sialic acid (NANA) and ranging from three to ten residues in length. Cows’ milk, and infant formulas, contain only trace amounts.
These human milk oligosaccharides (HMOs) are not digested in the small intestine. Small amounts are absorbed and found in the urinary tract. Most passes to the large intestine where it acts like dietary fibre.
Oligosaccharides containing N-acetylglucosamine promote the growth of bifidobacteria, which are the dominant colonic bacteria in breast fed infants.
Micro-organisms and their toxins gain entry to cells by attaching to specific sugars on the cell surface. Oligosaccharides in mucus and in human milk include particular sugars that can act as decoys for many specific microorganisms and so prevent their access to the body. HMOs have been shown to include receptors for E. coli, E. coli toxins, Campylobacter, Candida, Rotavirus and Strep pneumoniae.
How to manage breast feeding
The mother should be adequately nourished during pregnancy.
She should have watched others breast feeding and talked about it.
The baby should be put to the breast as soon as possible after delivery.
Frequent suckling stimulates prolactin secretion. Sucking more than six times a day maintains high basal prolactin as well as initiating prolactin surges with feeding.
Feeding should be on demand or baby-led.
Colostrum is a concentrated anti-infective fluid.
Relaxation and privacy are needed.
The baby should not be given other complementary milk or juice—only water if necessary.
The baby should feed from both breasts each time and start the feed with the breast used last.
Advice may be needed about sore nipples or breasts, oversupply, or undersupply.
Nutrition for the lactating mother
Except in malnourished communities, there is little evidence that dietary calories, protein, fat, water, or anything else have a consistent effect on milk volume. Regular and fairly frequent suckling is the well established stimulus. Human lactation works more by pull than by push.
Some constituents in the milk are affected by the mother’s intake.
Fatty acid pattern, vitamin A, thiamin, riboflavin, biotin, folate, vitamin B-12, and vitamin C are affected, especially downwards if the mother’s diet is deficient.
Zinc, iron, fluoride, and vitamin D may be responsive in some circumstances, but more research is needed.
Protein, lactose, total fat content, calcium—that is, the major proximate constituents of milk—do not appear to be affected.
Specific proteins in the mother’s diet might be excreted intact in small amounts and an allergic (IgE) reaction occasionally occurs in the baby.
The amount of caffeine in the milk after a cup of coffee is only about 2% of the maternal dose. Likewise, the alcohol concentration of breast milk is about the same as that of plasma so single drinks of coffee or alcohol, well spaced out, are harmless, but the babies of alcoholics can be affected. Beer stimulates prolactin secretion (at least in non-lactating women) and so might increase lactation. Milk production is reduced in heavy smokers.
The fat-soluble environmental contaminants, polychlorinated biphenyls, dry cleaning solvents, and organochlorine insecticides (DDT, etc), are stored in adipose tissue and excreted in the cream of breast milk (though the DDT group is fairly innocuous in man).
The mother’s need for extra nutrients
A good average production of breast milk is 800 ml/day, and the mother’s extra nutritional requirements are calculated from this and the average composition of milk, taking into account the available information about efficiency of absorption. The gross energy value of average human milk is 280 kJ/100 g and efficiency of conversion from maternal dietary energy to milk energy is assumed to be 80%.
Hence the energy lost in exclusive breast feeding in the first three months is:
800ml * 280KJ * 100 / 80 * 2.8MJ (675 Kcal)^13
If the mother does not eat the full amount of this extra energy she will lose some of the body fat put on during pregnancy. When the infant is getting other foods the energy expenditure on breast milk usually declines.
Most of the nutrients come along with the extra calories; lactating women usually have a good appetite and if this is satisfied by a mixed diet the nutrients that need watching (because there is little excess in the diets of non-lactating women) are calcium, iron, folate, and vitamin D.
The extra calcium can come from a pint of milk or two cartons of yoghurt. Calcium metabolism changes during lactation. There is some loss of bone density, which is apparently not prevented by calcium supplements. These changes are reversed when lactation ceases. There is no evidence that women who have breast fed have increased incidence of osteoporosis. Iron supplements may be advisable, and vitamin D supplements are recommended for any mother whose vitamin D status is in doubt.
Folate deficiency incurred during pregnancy may first show as anaemia in the puerperium. Zinc is secreted in the milk but staple isotope studies show increased zinc absorption during lactation.
A few mothers continue breast feeding towards or beyond 12 months.The major reasons for stopping in the first six weeks were insufficient milk (54%) and painful breasts or painful or inverted nipples (18%); the commonest reason for stopping between 6 and 16 weeks was also insufficient milk (66%). Those with insufficient milk early on never got lactation well established. Those with insufficient milk later may have had normal volume production but the baby’s energy needs started to outgrow this.
Some mothers choose to bottle feed from the start and others will change over from breast to bottle feeding after weeks or months, so they need practical advice.
A cows’ milk formula specially modified for infants should be used in which the protein has been reduced, the casein partly replaced by whey protein, the fat made more unsaturated, the lactose increased, sodium and calcium reduced, and enough of all the essential micronutrients added.
Bottles and teats should be washed in water and detergent, rinsed and sterilised by boiling in water or by standing covered in sterilising solution (usually hypochlorite) in a plastic container. It saves time to prepare several bottles at once. Empty the water out of each bottle, without touching the inside, then fill to the mark with recently boiled water that has cooled some minutes, not too hot or it will destroy some vitamins and may produce clumping.
Exactly the amount of power in the manufacturer’s instructions should be put into the bottle, using the scoop provided.
If the hole in the teat is too small it can lead to aerophagia or underfeeding. Milk should drip from the inverted teat at about one drop per second. Teats need replacing every few weeks.
Babies do not mind cold milk but usually prefer it warm. The bottle should be not warmed for too long and the milk’s temperature should be checked by dropping some on the parent’s skin. Infant feed should be not warmed in a microwave oven once it is in the feeding bottle. Very hot fluid at the centre of the bottle may be missed and may scald the baby.5 For about the first eight weeks of life babies need to be fed every three to four hours, including the small hours of the morning.
By the end of the first week most babies are taking 120-200 ml/kg per day (160 ml/kg corresponds to the old two-and-half fluid ounces per lb bodyweight).
Cereals or rusks should not be added to milk in the bottle and babies should not be left to sleep with a bottle in their mouth.
In the first six months
Young infants cannot deal properly with solid foods (in reality semisolid foods at first) for the first four months. The natural time for starting solids is when the energy provided by well established breast feeding starts to become insufficient.
Weight in the lower half of the standard percentiles without other symptoms is not an indication to augment breast feeding. Breast fed babies tend to put on weight (and length) a little more slowly than bottle fed infants.
six months body stores of several nutrients, such as iron, zinc, and vitamin C, are often falling in exclusively milk fed infants, whether from breast or bottle.
When solids are introduced, single ingredient foods should be used and started one at a time at half weekly intervals so that there is time to recognise allergy or other intolerance to each food. A little of the food on the tip of a teaspoon is enough at first, given after a milk feed when the baby is wide awake.
In the second six months
In the second six months other liquids can be given from a cup, especially citrus fruit juices. Untreated cows’ milk can sometimes cause gastrointestinal bleeding from irritation by the bovine serum albumin. This does not happen with boiled milk or infant formulas (which have been heat treated). Iron-fortified infant formula contributes to iron intake, which is critical in the second six months of life. It is wrong to add any salt to the foods given to infants.
An increasing range of foods is given in the second six months. Variety is likely to cover the needs for most nutrients and provide a basis for healthy food habits. Some fruits or vegetables should be given each day, but the most critical nutrients at this stage are protein and iron: finely minced beef and legumes should be given regularly and the protein in cereal foods should not usually be diluted by refining or by added fat or sugar.