____% of milk fat is in the form of triacylglycerides (TAGs)
98%
Other than TAG what are the other fat components in milk?
diacylglycerides
monoacylglycerides
cholesterol
cholesterol esters
FFA
phospholipids
What is enclosed within milk fat globules?
Core: TAG
Membranes: PL,CH, porteins
What % of milk energy do TAG make up?
55-60%
Infants need _______kg fat in the 1st 6 months
1.4 - 1.7
Fat has a low ______________________ cost. __% of energy of absorbed TAG invested for cost of adipose tissue vs. ___% for CHO
osmotic or metabolic
1%
25%
Where do milk FAs of ≤16C come from?
synthesized in the aveolar cells within the mammary gland from glucose
Where do milk FAs of ≥18C come from?
maternal adipose stores and diet
Maternal Milk Lipid synthesis increased ___________ activity just preceding and during lactation leads to increased _______________ in the mammary glands leaing to increased _____ uptake into the mammary gland
prolactin
lipoprotein lipase
FFA
Maternal Milk Lipid synthesis in maternal adipose tissue decreased ________________ activity leads to __________ FA uptake from ____________________into mammary tissue
lipoprotein lipase
channels
diet and internal stores
List advantages of human milk vs bovine milk in terms of fat absorption and composition.
higher proportion of palmitate at 2-position of TAGs
better lipolytic activity
higher oleic and lower SFA content
5x greater EFA content than cow's milk
linolenic acid content of 0.7-1.3% in breast milk vs 1-5% in formulas
better mineral bioavailibility
Better Ca:P ratio
lower solute load (Mg, Na, K, Citrate) in human breast milk
what is the primary SFA in cows milk and human milk?
palmitic acid in 2 position is an advantage in terms of absorption, why?
MAGs with palmitic acid are much netter absorbed than free palmitic acid
MAGs from better micelles with bile salts than free palmitic acid- lower melting point
SFA, PUFA, and MUFA have lower melting points what does this mean for their emulsification?
need lower bile salt concentration to emulsify them
What decreases SFA absorption?
SFA complex and form insoluble soaps with Ca and Mg leading to decreased absorption
inhibit Ca absorption
not soluble in alkaline pH --> non-absorbable
What lipases present in human breast milk improve fat absorption and lipolytic activity?
lipoprotein lipase from maternal serum
bile salt stimulated lipase
pancreatic like lipase
Which has more CH human milk or cow's milk?
human milk has 2x [CH] than cow's milk
Why is higher oleic and lower SFA content better?
oleic acid is better absorbed than saturated fat
T or F- EFA is 5x greater in breast milk then cows milk but it can be higher in infant formula
T
EFA in infant formula is 10-16% of energy
List the major factors that influence breast milk composition
gestational ages
length of lactation
increase in maternal fat content will lead to an increase in milk fat content
insufficient maternal fat reserves put on during pregnancy lead to fat content of breast milk going down significantly
malnutrition
How does malnutrition affect milk composition?
does not seem to affect the immune factors in mature milk but immune factors in colostrum are decreased
milk protein content is not easily affected by malnutrition unless prolonged and severe protein calorie malnutrition
no evidence that alteration in maternal diet will affect the total milk fat content nor milk volume
only severe malnutrition in the form of severe energy restriction will hinder milk volume
Long chain fatty acids are ______ higher in breast milk than infant formula
5 times
DHA accounts for ______% in breast milk
How can the amount be increased?
How much DHA is in formula?
0.1 - 0.3%
can increase by fish intake
negligible amounts in formula
What effects occur from DHA deficiency?
impaired vision and learning
Arachidonic acid _______% in omnivores
___________ levels are lower in formula fed infants than breast fed infants but __________ arachidonic acid content is similar in both groups
0.4- 0.6%
plasma
brain
low amounts of DHA --> low EPA, how does this effect infants?
low RBC PL content of arachidonic acid
associated with decreased growth
What can be done to formula to improve growth and cognitives performance?
enriching the formula with DHA only
Linolenic acid addition alone does not seem to optimally increase DHA in RBC PL
What is the second most abundant constituent in breast milk after water? What is its total concentration?
lactose
70 g/L
Lactose is the least variable component in milk its exerts _______% of osmotic pressure of milk.
60-70%
What does lactose's contribution to osmotic pressure result in?
leads to milk isoosmotic to plasma
leading to low energy cost to maintain osmolarity
stimulates beneficial microorganisms in the gut (e.g. lactobacilli)
What is the function of amalyase in breast milk?
aids in lactose digestion
Besides contributing to osmotic pressure what is another function of Lactose in breast milk?
aids in mineral absorption by forming soluble chelates with minerals
What compounds aid in mineral bioavailability in breast milk? What mineral does each one aid in digestion?
lactalbumin metalloenzyme binds Ca and Zn
xanthine oxidase- Fe and Mo
glutathione peroxidase Se carrier
alkaline phosphataste: Zn and Mg
lactoferrin Fe (high bioavailable form)
What is the Ca:P ratio in breast milk?
2:1
What is the Ca:P ratio in cows milk?
1.5:1
What effects does having a low P relative to Ca have on infants?
increased gut excretion of Ca thus less Ca is excreted in gut with breast milk
What effect does having a lower solute loas in human breast milk have on infants?
less stress on infants kidneys when combined with the lesser protein content of human breast milk
What are the characteristics of preterm milk?
higher energy, protein, Na and Cl
lower lactose
insufficient in Ca, P, Mg, vit D --> milk should be fortified
Why does preterm milk have higher protein and energy?
preterm infants have a rapid growth rate approximating in utero growth
What happens to breast milk with increasing length of lactation?
lower total protein, Ig's and fat soluble vitamins
increased lactose, fat, energy, and water soluble vitamins
There is an increased proportion of which FAs in mature milk from colostrum? Why?
C8:0, 10:0, 12:0, 14:0, and 16:1
less contribution from dietary and maternal stores
changing needs of infants: decreased rate of nerve cell division, myelination rate increases (need MCFA synthesized by mammary glands for myelin sheath synthesis)
What is milk fat content influenced by?
length of time between feedings and time of nursing
foremilk= low fat
hindmilk = 3x increase in milk fat content
What result does insufficient maternal fat reserves put on during pregnancy have on breast milk?
fat content of breast milk can significantly decrease to 1.0g/100mL
What is the influence of diet on milk composition?
CH and PL content is unaffect by changes in diet
milk FA composition is affected by dietary fat composition
linoleic acid content in human breast milk depends on diet
fat soluble vitamins are not much affected by maternal malnutrition
water soluble vitamins generally affected by malnutrition
When is milk CH content affected/changed?
milk CH is increased in severe hypercholestolemia
CH and PL are integral components of milk _____________
Their secretion rate correspond to the total quantity of ________________________
fat globules
milk fat secretion
What precent linoleic acid do vegetarian mothers have in their diet?
>30%
What precent linoleic acid do omnivore mothers have in their diet?
>6.9 to 18%
What precent linoleic acid do very low fat mothers have in their diet?
<1%
What are the effects of a low fat energy restricted diet on milk composition?
increased proportion of C16
saturated LCFA predominant
indicates that stored fat is used for fat synthesis
What are the effects of vegan mothers on infants FA profile?
insufficient DHA (decreased n-3 FA intakes and reserves in vegan mothers
high intakes of arachadonic acid (high intake of linoleic acid in vegan mothers)
Which fat soluble vitamin content changes in in milk? What conditions cause it to change?
Vit D
decreases with decreased exposure and decreased dietary intake
maternal supplementation can cause toxicity in the infant
What does excessive vit D in maternal milk result in?
hypercalcemia
failure to thrive
vomiting
constipation
anorexia
What population has infantile B12 deficiency been observed in?
vegetarians who breast fed their infants
What population has infantile beri-beri been observed in?
in infants nursed by mother with Beri-Beri
T or F Folate milk content is affected by deficiencies in mother?
False
Folate milk content is unaffected
How does low maternal B6 occur? What are the implementation for their infants?
Low maternal B6 is associated with a protein poor diet
This leads to an increased risk of B6 deficiency in the infant and decreased attentiveness in infants
What are the results of low maternal vitamin C intake?
decreased Vit C content in milk
Se and Id milk content is closely linked to ____________________________
maternal dietary intake
T or F maternal supplementation of water soluble vitamins will continually increase their content in milk
F
they will cause an increase until a plateau is reached
In general what is the relationship between maternal dietary mineral intake and their content in milk?
no significant relationship b/w maternal intake and breast milk content
What major minerals are maintained as a constant over a wide range of intakes?
Major minerals: Ca
Trace minerals: Cu, Zn, Fe
What is considered excessive I intake? and what will it result in?
60% from salt 25% from dairy especially from milk 100 to 1300 ug/L
leads to excessive I content in breast milk
What are the disadvantages to breast feeding?
environmental contaminants
vit K deficiency
PKU
Galactosemia
HIV infection
premature infants require fortified breast milk
breast milk jaundice
development of moderate to severe eczema due to breast milk allergy
Why may the risk of environmental contaminants be greater for the fetus then breast fed infants?
fetuses have more sensitive CNS, higher does per kg body weight and less fat tissue to store contaminants
What are the implications of heavy metals and pesticides in breast milk?
does not seem to be toxicologically siginifcant quantities except in the case of an environmental catastrophe (Minamata Bay, Japan --> Hg into water supply --> severe neurological disordered)
What implications do dioxins and PCBs have on the newborn?
suggested that dioxins and PCBs may interfere with vit. K metabolism; may contribute to late hemorrhagic disease of new borns (bleeding, easy bruising, mucosal bleeding and severe intracranial hemorrhaging)
When are PCBs and dioxins excreted in higher amounts?
1st week after birth
What is the source of PCBs and dioxins?
from stored levels in maternal adipose tissue
no difference b/w a high dioxin diet and low dioxin diet during lactation
daily intake contributes only 14% of the total excretion of dioxins in breast milk
Breast milk is low in vit K, what effects could this have on new borns?
late hemorrhagic disease of newborns
developmental immaturity to synthesized prothrombin
low prothrombin levels (20% of adult values) 1-7 days postpardum
newborns have sterile gut- no bacterial contribution to vit K intake
poor Vit K stores at birth
How much more Vit K is there in cows milk than breast milk?
4x
What is done to help infant vit K status?
it is injected after birth
i.m. injection (0.5-1mg dose)
required by law
this lead to an increase of late hemorrhagic disease
How do PCB interfere with vit K metabolism?
PCBs induce microsomal cytochromes P-450 activity leading to microsomal gamma-glutamyl carboxylase of which Vit K is a substrate and a cofactor
vitamin K is not recycled in the normal salvage pathway but is metabolize and excreted due to induction of Cytochromes P450
observed with anti convulsants and phenobarbital
LHD is ___ times higher in Japan than in western countries
Why is this?
2 times higher
in Japan increase in fish consumption lead to an increase in PCB thus a higher rate of LHD
Most commonly used drugs are excreted into milk but only a handful pose a significant health risk. What characteristics are desirable for drugs taken while breast feeding?
drugs with short half life cleared from system between feedings
drugs less readily excretable in milk
Dose and duration of drug use are important regarding their effect on breast milk. What are the effects of chronic asprin that dont occur with just one dose.
rashes, acidosis, and altered platelet function
What are the effects of hallucinogenic drugs such as heroin and cocaine on infants?
tumors
irritability
withdrawal symptoms in infants
What is a side affect for the infant of a mother taking anti-convulsants?
infants need supplementation of Vit K
What are some side effects of a lactating mother taking oral contraceptives?
gynecomastia (enlarged breasts) in young infants
suppress lactation
What are some side effects of a lactating mother taking antibiotics?
allergic reactions
vomiting
refusal to eat
What are the effects of 1-2 cups caffeine a day on infants
accumulates in infants over time
may interfere with Fe availability and status in infant
restlessness
irritability
sleepiness
What are some side effects of a lactating mother taking seditives?
lethargy in infants
What are some side effects of a lactating mother smoking?
decreased milk volume
less weight gain in infants
associated with SIDS (sudden infant death syndrome)
What are some side effects of a lactating mother consuming hot spices and garlic?
distress in infant
alteration of the milk flavor
What are some side effects of a lactating mother consuming alcohol?
decreased infant milk intake
decreased milk production
What are some side effects of a lactating mother exercising?
compatible with breast feeding
intense exercise leads to lactic acid which leads to increased acidity in breast milk
What is PKU?
Phenylketouria
an autosomal recessive metabolic genetic disorder
enzyme phenylalanine hydroxylase (PAH) is non-functional
PHA is necessary to metabolize phenylalanine and tyrosine
phenylalanine accumulates and is converted to phenylpyruvate which is detected in urine
How is PKU dectected and treated in infants? What happens if it is not treated?
infants screened at birth with a number of other inborn errors of metabolism
Lafenalac is preferred source of infant formula with low PHE content
otherwise infants will get severe mental retardation
What is galactosemia?
a rare autosomal recessive disorder
occurs in 1/60,000
inability to metabolize galactose sugar produced from lactose
galactitol, a reduced form of galactose that is highly toxic and causes severe mental retardation, cataracts and liver damage
How is galactitol produced in people with galactosemia?
Galactose + ATP ---> galactose–1-P + ADP + Pi
galactose–1-P ---> UDP-Galactose + glucose–1-P converted via 1-P uridyl transferase (deficient) -> cannot convert galactose to UDP-Galactose
Galactose–1-P accumulates producing galactitol, a reduced form of galactose that is highly toxic
should women with HIV breast feed?
it is not recommended except in developing countries since there have been 1.5 million deaths/ year due to poor sterilization of drinking water
How many people do not have enough safe drinking water?
1.2 billion people
Why do premature infants require fortified breast milk?
breast milk is insufficient in Ca and P for skeletal growth
How often does breast milk jaundice occur? How long does it last? Why does it occur? How is it treated
uncommon 2-4% of infants
starts day 4 and ends day 5-15
metabolite of progesterone, pregnane-3-α-20-β-diol; inhibits bilirubin conjugated by glucoronyl transferase
treatment is extra water, phototherapy
if hyperbilirubinemia persists or is excessively high-> withhold milk for short period of time
What does a baby getting eczema while breast feeding indicate?
onset of allergies associated with blunting of growth
after breastfeeding was discontinued symtoms of atopic eczema improved as did rates of growth
What are the effects of prolonged feeding of breast milk without introduction of solids beyond 6 months.
reduced growth rate
feeding adversion
What precent of energy should solids account for in a 6 month old infant and a 10 month old infant?
20% at 6 months
50% at 10 months
Iron deficiencies may occur after _____months of age if Fe rich foods are not introduced
4-6
T or F formulas are fortified with Fe
T
T or F It is agreed upon that breast fed infants should receive Fe supplementation
F
it is controversial as Fe deficiency is less common in breastfed infants
How much Vit D should breast fed infants be supplemented? Why?
10µg/day
recommended due to generally poor exposure to sunlight in Northern climates even though breast fed infants are more protected from Vit D deficiency
