Milk Composition
Minerals & Vitamins
Leo Timms
Iowa State University
Composition of Milk
• Water, CHO (lactose), fat, protein,
• MINERALS
– Milk contains most minerals found and
needed in the body!
• VITAMINS
– Milk contains all vitamins found and needed in
the body!
• It really is the most perfect food!
Minerals
• Role in the body:
–
–
–
–
–
–
Metabolism
Bone formation and growth
Oxygen transport
Water balance and maintenance
Immune system
Antioxidants
• Mineral interactions
• Toxicity vs. Deficiency
Minerals
• Functions in the mammary gland:
– Maintain
• pH
• Ionic strength
• Osmotic pressure
– Contribute to buffering capacity
MINERALS
•
20 MINERALS ESSENTIAL TO HUMANS?
• MACRO
• MICRO
MINERALS
20 MINERALS ESSENTIAL TO HUMANS?
• MACRO
Sodium
Potassium
Chloride
Calcium
Magnesium Phosphorus
•
• MICRO
Iron
copper
zinc
manganese
Selenium
iodine
chromium cobalt
Molybdenum
Fluoride
arsenic
Nickel
silicon
boron
Animal Science 337: Extra Credit #3
1. Look at the handout that shows milk composition
of different species. Look at species with high and
low lactose and compare other components. Also,
why would you expect other components to be
associated positive or negative to lactose? (7 pt)
2. Some people react to cows milk and it is stated
that they are lactose intolerant. When they change
to goat milk, they feel better. Is it psychological or
real and does lactose drive this response? If not,
then what? (6 pt)
2. I want more Calcium in milk products naturally?
Can I do it with diet? Answer either way /justify! (7)
• DUE DAY OF 2ND EXAM
Constituent
mg/100ml milk
Calcium (Ca)
123
Phosphorous (P)
95
Magnesium (Mg)
12
Potassium (K)
141
Sodium (Na)
58
Chlorine (Cl)
119
Sulfur (S)
30
Citric acid
160
Cow
(Paul &
Southgate 1978)
Human (DHSS,
1977)
Sow (Elliot et al.
1971: Bowland,
1966)
Sodium
50
45
50
Potassium
150
55
80
Calcium
120
33
210
Magnesium
12
3
30
Chloride
95
43
100
Phosphorus
95
45
150
Calcium/
Phosphorus
1.26
2.20
1.40
Milk MACROminerals
•
•
•
•
Sodium Potassium Chloride
Calcium Magnesium Phosphorus
Independent of dietary intake!!!
Colostrum: higher in everything but K
3 days in milk: normal but K high
Little variation across lactation
Sodium, Potassium, Chloride
• Normal milk:
– higher in [K]
– lower in [Na]
• compared to blood plasma
• Membrane Na-K pump eliminates Na and concentrates K
– Na, K, Cl follow the concentration gradient into the
vacuole or alveolar lumen
– Cl is actively pumped by a membrane pump into the
cell against a gradient
– Na: primary regulator of extracellular fluids
• Na / K / Cl: free ions in milk- totally absorbed
– concern for human neonate – renal
Calcium and Phosphorus
• Required in large quantities for the growing
neonate
• Calcium is found as:
– Free calcium
– Casein-bound calcium (majority; up to 90%)
– Calcium--inorganic anions
• Ca / P / Mg : 40-90% assoc. w/ casein micelle
– highly absorbed due to casein / lactose inter.
Calcium transport
• Little movement from milk to blood
– Cannot pass through tight junctions
• Golgi
– Bulk of uptake
• Calcium pumps
– Up and down regulated depending on stage of
lactation
• Can you change Ca content of milk through
diet? (Extra credit #3!!!!!)
Milk MICROminerals
• Trace minerals enter the milk by
– Diet
– Contamination
• Metal containers
• Environment
• Many are co-factors for enzymes
Iron
• Low in milk
• Bound to:
– Lactoferrin (humans – better absorption)
• Protein
• Anti-microbial
– Some caseins
*** no correlation with intake!!!!!!!!!
Copper
• Bound to:
– Caseins
– β-lactoglobulin
– Lactoferrin
– Milk fat membrane proteins
Zinc
• Bound to:
– Casein
– Lactoferrin
– Formation and maintenance of keratin in teat
canal
Sulfur
• Transported into cell as part of AA
•Met, Cys
• Milk protein
Molybdenum
• Bound to:
– Xanthine oxidase
• Cell membrane
• Inner surface of milk fat globule membrane
Manganese
– 67% casein bound
– Milk fat membrane proteins
Cobalt
– Vitamin B-12
– Incorporated into protein in RER
– High in colostrum
– Propionate  Glucose
Iodine
• Organic Iodine
– Chelated
– EDDI
• Iodine dips/foot rot treatment
• Mammary tissue sequesters iodine
– Iodine totally available
• Legal limits
– Toxicity
• Decreases immune function
• Cause of acne??
SELENIUM (Se)
• Essential for all animals
• Often in conjunction with Vit E
• Animal products great source for humans
• Increase levels in milk through feeding
• Organic selenium (yeast)
• Increased levels in animals (health bene?)
• Toxicity in animals to serve people??
Vitamins
• Vita – Latin word for “life”
• Amine – compound containing nitrogen
• Roles in the body include:
–
–
–
–
–
Metabolism
Oxygen transport
Antioxidants
Immune system
Help the body use
• CHOs
• Protein
• Fat
• Milk contains all vitamins required by mammals
Mastitis
• Infection of mammary gland
• Clinical mastitis: visible signs
• Subclinical mastitis: elevated SCC
What do vitamins have to do with it?
53,000 IU/d vitamin A; 173,000 IU/d, 53,000
IU/d + 300 mg beta-carotene
•Less new mammary gland infections
(clinical mastitis)
Fat-soluble Vitamins
• Includes Vitamins:
–A
–D
–E
–K
• Associated with the milk fat globule
Vitamin A
•
•
•
•
Yellow color of milk fat is from ß-carotene
Lower efficiency of conversion
Some countries fortify with vitamin A
Species differences
– Cows, humans, and mares contain both Vit.
A. & b-carotene
– Goat, ewe, buffalo, and sows milk contains
Vit. A only
Vitamin D
• Antirachitic activity
• Levels related to ergosterol in
feed/sunlight
– Feeds drop in ½ during winter
– Summer milk higher
• Higher in Guernseys, Jerseys, colostrum
• Ca absorption from the intestine
• Milk is often vitamin D fortified in US
Vitamin E and Vitamin K
• Vitamin E : tocopherol
–
–
–
–
–
Antioxidant, protects lipids in milk fat
Related to diet (summer pasture > winter feed)
Highest in colostrum
Low levels in milk
Associated with selenium
• Vitamin K :
– Very low levels in milk
HOW MANY
B VITAMINS
ARE THERE?
12
8
Water-soluble Vitamins
- found in the aqueous phase
• B-Vitamins
– Thiamin, riboflavin, folate, B12, etc.
• All are found in milk
• Influenced by diet & breed and species
– Change to pasture
– Guernsey/Jersey higher than Holstein
– Colostrum higher than normal milk
• Synthesized by rumen microflora and large
intestine
• Many are enzymatic co-factors
• Extremely important in nutrient metabolism!
Vitamin C
• Synthesized by ruminants
• Two forms
– Ascorbic acid
– Dehydroascorbic acid
• Colostrum higher than normal milk
• Much is destroyed during milk processing
Other normal constituents in milk:
• Hormones
– Levels follow trends of blood levels
– Changes with estrous cycle, pregnancy, etc.
– Usually lower than blood
• Oligosaccharides
– Breakdown products of glycosylated proteins
• Cell Metabolites
– Gases, alcohols, aldehydes, ketones, carboxylic
acids, nonprotein nitrogen, sulfur-containing
compounds, phosphate esters, nucleotides and
nucleic acids
• Epithelial cells
– Sloughed off from duct linings
Abnormal constituents in milk:
• Toxins
– Plants, metals (lead, arsenic, etc.)
•
•
•
•
Viruses
Pesticides and Herbicides
Radionuclides
Bacterial Organisms
– Johnnes, Mycoplasma, Salmonella
•
Drugs
– Antibiotics
•
Off-flavors
– Weeds, poor barn ventilation, ketosis, etc.
• Oxidized flavors
– Exposure to Cu and Fe
• Exposure to light
– Causes lipid oxidation, rancid flavors