Components of breast milk (II)

In the previous presentation we referred to the macronutrients present in breast milk, in this one we will learn about the rest of the components: the micronutrients, the bioactive components and the microbiota of breast milk.

Micronutrients present in breast milk

The vitamin and mineral stocks contained in breast milk depend on the diet and maternal reserves, therefore it is recommended that during lactation the mother should increase the intakes of certain micronutrients, such as vitamins A, E, B1, B2, B3, B6, B9, B12, choline and C; and the minerals calcium, iron, iodine, zinc, magnesium and selenium.

Vitamins present in breast milk

A well-nourished mother provides sufficient amounts of most of the vitamins necessary for the proper growth and development of the child, however, in the following cases it is recommended to supplement the mother or the infant:

• Folic acid and Vitamin B12: Their concentrations are low in the milk of vegetarian and vegan mothers; therefore, supplements of both vitamins are recommended for the duration of breastfeeding.

• Vitamin C: Its concentration is low in the milk of smoking and diabetic mothers. Vitamin C supplements are recommended -especially for smoking mothers- while breastfeeding.

• Vitamin D: Its concentration is generally low in breast milk. When the infant does not receive the necessary daily intake due to the action of solar radiation on the skin, it is recommended to supplement with 15 IU per day.

• Vitamin K: Its concentration is low in breast milk, so a dose is administered to the infant at birth to prevent hemorrhage.

Minerals in breast milk

The concentration of minerals in breast milk is in correspondence with the infant's metabolic capacity and nutritional requirements.

The absorption rates of the minerals contained in breast milk are higher than the absorption rates in other substitute milks, such as cow's milk.

The following are some peculiarities of the content and assimilation of the main minerals contained in breast milk:

• Iron: The concentration of iron in breast milk is low, however about 70% is absorbed; a much higher proportion than in cow's milk, which is only 30%. Iron is involved -among other functions- in the production of red blood cells and brain development of the infant.

• Iodine: The iodine content in breast milk depends on the mother's diet. For this reason, it is recommended to use iodized salt in the preparation of food and to consume fish three times a week. In some cases, specialists recommend iodine supplements to the mother; this treatment should be well supervised since excesses of iodine could affect the health of the mother and the infant as much as deficiencies.

• Iodine is the essential constituent of the hormones synthesized in the thyroid gland, involved in the growth, neuromuscular processes, and cognitive development of the infant.

• Zinc: Its concentration in breast milk is lower than in cow's milk, but its assimilation is much higher. Zinc is involved in the development of the immune system, is part of some hormones and is a cofactor of enzymes involved in metabolic processes.

• Copper: Its concentration in breast milk is low, although copper deficiencies are not manifested in exclusively breastfed infants. About 25% of the copper contained in breast milk is absorbed, while only 18% is absorbed in cow's milk. Copper is a cofactor of enzymes involved in glucose metabolism and in the synthesis of hemoglobin, phospholipids and connective tissue.

• Calcium: About 55% of the calcium contained in breast milk is absorbed, while only 38% is absorbed in cow's milk. Breast milk enhances its optimal utilization since it provides phosphorus, with a calcium: phosphorus ratio of 2:1. Calcium is involved -among other functions- in the construction and maintenance of bone tissue, in nerve transmission and in the regulation of the heartbeat.

Bioactive elements present in breast milk

A bioactive component of a food is considered to be those elements that influence cellular activity and physiological mechanisms and that provide a health benefit beyond those considered as basic nutrition.

Some bioactive elements identified in breast milk are:

• Omega-3: Intervenes in the brain and visual development of the infant Antimicrobial molecules-lactoferrin, lysozymes. They fulfill defense and anti-inflammatory functions.

• Metabolic hormones-adiponectin, leptin, ghrelin. They act as messengers so that the organism can respond to stimuli and interact with the environment.

• Immunoglobulins A, G and M -IgA, IgG, IgM-. They act as a protective barrier against viruses and bacteria.

• Breast milk oligosaccharides (HMOs): favor the development of microorganisms that promote beneficial effects on health.

• Cytokines and growth factors: regulate inflammation, act as an intestinal barrier and modulate the immune system.

• The microbiota of breast milk: they favor the intestinal balance of the newborn and intervene so that the organism does not overreact to benign agents.

Microbiota present in breast milk

Contrary to what was believed until recently, human milk is not sterile; more than 700 different species of live microorganisms - called probiotics - have been identified in it, which promote many positive effects on health. Among the bacterial genera most represented in breast milk are Staphylococcus, Streptococcus and Bifidobacterium.

The probiotics contained in breast milk are different in each woman, depending on many factors, such as the type of birth, age, medical conditions, medications and the mother's diet, among others.

Milk also contains prebiotics - non-digestible substances that selectively stimulate the growth of probiotic organisms - for example, the oligosaccharides in breast milk favor the growth of bifidobacteria.

Importance of the microbiota in breast milk

• Contributes to the emergence and development of a strong immune system in the baby, protecting it from infectious diseases.

• Reduce the risk of allergies (asthma, allergic rhinitis, etc.).

• Reduce the risk of developing obesity and type 2 diabetes mellitus.