What is lactose?
Prime source of carbohydrates for all young mammals
How is lactose digested?
Lactose is a disaccharide; lactase hydrolyzes it
What is lactase non-persistence?
The ability to digest lactose ceases after childhood; they no longer produce lactase
What determines whether someone continually produces lactase after childhood?
Genetics
What happens if you cannot digest lactose?
Lactose is fermented by bacteria in the colon, which creates gas like carbon dioxide, methane, hydrogen
It osmotically attracts fluid into the bowel lumen; diarrhea
What is lactase persistence?
Genetically modified continued activity of lactase enzyme in adulthood
Is lactase persistence dominant or recessive?
dominant; only one copy is required for expression
What is the standard to know if someone has lactase persistance?
If they can drink a glass of milk without any unpleasant side effects
What did lactase persistance arise?
6-10 000 years ago
How is lactase persistence different in Europe as opposed to Africa?
Their gene variants are different; they have the same end result
What populations have the highest prevalences of lactose tolerance?
Population with a long history of consuming milk products
What is the gene-culture coevolution hypothesis starting with pastorlaism?
- Populations were practicing pastoralism
- The lactase persistence mutation occurred
- The allele offered a selective advantage and became fixed in the population
What is the gene-culture coevolution hypothesis starting with lactase persistence?
- The mutation occured
- The allele became fixed in the population at high frequencies
- Pastoralism spread
When did fermented milk products start to be produced?
10 000 BCE
What are the benefits of fermented milk products?
- Someone lactase non-persistence can tolerate products where lactose is broken down by the lactic acid fermentation process
- They can survive in warmer climates
What is the theory on the beginning of bacterial fermentation of milk products?
Milk was stored in a warmer climate, and due to the climate, and bacteria from where it was stored (ex. animal hides), it may have naturally fermented
What are the evolutionary advantages to being able to consume milk and dairy products?
- Calcium for skeletal integrity (most concentrated and bioavailable form of calcium)
- Relatively clean liquid
- Numerous nutrients (Vitamins A,D,B12; riboflavin, calcium, phosphorus)
- Energy, fat
- Longer use of animal (milking yields more than meat)
What requirements are needed for skeletal integrity?
- Vitamin D which increases calcium absorption (SI), reabsorption (Kidney), and bone mineralization
- Protein
- Strong bones before 30, and exercise
