Nutritional Aspects Of Lactation

Question 1

What is the purpose of prolactin?

Answer 1

Prolactin leads to mammary gland development and to milk production.

Prolactin stimulates the synthesis of milk proteins and lactogenic enzymes.
The high prolactin level during pregnancy is not maintained after delivery.

During nursing, however, prolactin release surges after suckling

Question 2

Prolactin and oxytocin are…

Answer 2

Essential for lactation

Question 3

What is the use of oxytocin?

Answer 3

Oxytocin causes the release of milk into the lactiferous ducts and sinuses so that it can be removed by suckling.

This is known as milk ejection or let-down reflex.

Release of oxytocin happens after suckling but can become a conditioned response by visual stimulation or conscious thought.

Question 4

Describe milk

Answer 4

Milk is a dispersion of
1. milk fat globules with TAGs
2. casein micelles with protein,
calcium and phosphorus

all in a phase of milk serum with lactose,whey protein, vitamins and minerals

Water: 87%
Fat: 4%, large variability
Protein:1%
Lactose: 7%

Question 5

How does human milk change from colostrum, transition milk to mature milk?

Answer 5

• Colostrum (first milk is the best for the newborn)
• Produced during pregnancy and up to 4-5 days postpartum
• Primary functions are supporting the immune system and cellular growth • Viscous fluid with yellow color due to high vitamin A content
• Highest protein content mainly from secretory IgA and lactoferrin.
• Lower in lactose than mature milk

Question 6

Human milk…

Answer 6

A dynamic body fluid which changes in composition

Question 7

What is transition milk?

Answer 7

Transition milk

• Produced after first week of lactation (5-14 days postpartum)
• Protein content and secretory IgA is less than in colostrum, whereas the content of lactose, lipid, water-soluble vitamins, and calories is greater.
• The volume increases by the end of the second week postpartum

Question 8

What fats are in human milk?

Answer 8

TAGs and cholesterol
Fatty acid composition in TAGs includes medium- and long chain fatty acids synthesized in the lactating mammary gland. TAGs are rich in oleic acid (36%) and contain PUFA (w6 > w3) from maternal diet including arachidonic acid (ARA) and DHA

Question 9

W(at carbs are in human milk?

Answer 9

Lactose and prebiotic HMO

Question 10

What proteins are in human milk?

Answer 10

High whey to casein ratio in comparison to cow’s milk Nutrients rich in essential and conditional essential amino acids Proteins with non-nutritive functions

Question 11

What are the vitamins in human milk?

Answer 11

Rich in vitamin A, B-vitamins and vitamin C
Low in vitamin K and vitamin D, sunlight exposure of infant
recommended

Question 12

Whaat enzymes are found in human milk?

Answer 12

Enzymes

1. Lysozyme
2. Bile-dependent lipase
3. Many different enzymes, some with unknown functions

Question 13

What bioactive functions are in human milk?

Answer 13

1. Leukocytes protect the infant against infections
2. Immunoglobulin secretory IgA protects mucosal surface of the intestine of the infant
3. Lactoferrin, cytokines, growth factors and hormones
4. Many more

Question 14

Describe whey protein

Answer 14

• Mostlya-lactalbumin

• Easier to digest than casein. It
does not precipitate at acid pH.

• Especially rich in leucine for stimulation of protein synthesis.

Question 15

Describe Casein

Answer 15

• Caseinmicellescontainwater, calcium and phosphorus
• Slow digestion of the protein, precipitates at acid pH (curd)
• Especially rich in proline for collagen synthesis

Question 16

What milk has highest whey:casein ratio?

Answer 16

Highest in colostrum

Question 17

What are the advantages of whey in human milk?

Answer 17

a. a-lactalbumin: is the predominant protein in whey and is often referred to
as the whey protein. It is rich in cysteine and tryptophan.

b. Lactoferrin: binds iron and inhibits growth of iron-dependent bacteria in the
GI tract of neonates and infants.

c. Lysozyme: is an enzyme that protects the infant against E. coli and Salmonella. It promotes the growth of healthy intestinal flora and has anti-inflammatory functions.
d. Immunoglobulins: mostly IgA which inhibits binding of pathogens, and protects the intestin

Question 18

Whaat are 3 main types of infant formulas?

Answer 18

1. Cow milk-based formula (often whey added)
2. Soy-based formula (not for premature infants)
3. Specialized formula (hypoallergenic or lactose-free)

Additives may include:
Lactoferrin, HMO, ARA, DHA, lutein, taurine, choline, vitamins,
and many other components dependent on the chosen formula

Question 19

What is the correlation of HIV and breastfeeding?

Answer 19

• “The CDC and American Academy of Pediatrics recommend that in the US, where mothers have access to clean water and affordable infant formula, HIV-infected mothers completely avoid breastfeeding their infants, regardless of anti-retroviral therapy (ART) and maternal viral load.”
• “In resource-limited settings like in some parts of Afrika, the WHO recommends that HIV- infected mothers breastfeed exclusively for the first 6 months of life, and continue breast- feeding for at least 12 months, with addition of supplementation of complementary foods. These mothers should be given ART to reduce the risk of transmission through breastfeeding.”

• WHO: “Breastfeeding is one of the foundations of child health, development and survival, especially when diarrhea, pneumonia and undernutrition are common causes of mortality
among children younger than five years.