Lactose Tolerance- Student Guide
What did they think long-term feeding of lactose to people who are malabsorbers result in? Did it?
an increase in lactase activity; no change
What type of disorder lactose tolerance?
autosomal recessive condition
Loss or persistence of lactase is what type of change? What program is it apart of?
developmental change that is part of a genetic program
Which Miller Children are tolerant? Which are intolerant?
Fred, Niles, Linda are tolerant/ Jane is intolerant.
Does it appear that lactose intolerance (or tolerance) is an inherited characteristic? Explain!!
Yes, it is an autosomal recessive trait
What form is the Carbohydrates in
a form of lactose- a disaccharide
Plain unflavored yogurt with what types of cultures can be tolerated?
active bacteria cultures
Symptoms in lactose intolerant patients as result of lactose in colon
acute gastrointestinal distress
Onset of symptoms related to this condition varies as to __
age
Galactose and glucose are combined in ___ to yield __
b-linkage to yield the sugar lactose
Why can't frozen yogurt be tolerated?
been pasteurized and bacteria eliminated
How can 2 parents who are both tolerant produce children who do not? Why is the most probable mode of this inheritance?
both are heterozygous- autosomal recessive
Other foods to increase calcium?
broccoli, soybean products, canned salmon with the bones
What secretes the enzyme for lactase?
brush border cells of the intestinal epithelium
Special advantage of galactose in infant nutrition:
building material in brain information
What are the products of lactose digestion?
calcium & simple sugars
How can calcium foods be substituted?
canned fish with bones, dark green vegetables and beans
Purpose of lactase enzyme?
capable of splitting the molecule by hydrolysis. Without lactase, the lactose would pass into the colon undigested.
What does human mother's milk have more of compared to any other mammal?
carbohydrates
What does galactose in the liver do?
changes to glucose and elevates blood glucose levels
Define hydrolysis?
chemical breakdown of a compound due to reaction with water
What is the source of lactase enzyme?
cultured bacteria
What did they thin Depriving persons who are absorbers of lactose for months at a time results in? Did it?
decrease in lactase activity; no change
Parents are tolerant but children are intolerant. Explain?
Both parents heterozygous
Tests for Lactose intolerant (4)
-Hydrogen breath -lactose-loading test & fasting -blood glucose test -tolerance symptoms test drinking milk on empty stomach
3 options regarding intolerance dairy consumption?
1. consume less lactose 2. limit dairy consumption to fermented forms like yogurt and cheese 3. add lactase enzyme to milk
Rank in order from most intolerance to least: Caucasians, Asians, Mexican-Americans, American Indians, African Americans
1. indians 2. mexican-americans 3. asians 4. african americans 5. american caucasians
Dairy products developed to solve this problem? (2)
1. lactose-reduced products (70%) that have had lactase enzyme added 2. Tablets to remove lactose
Onset of symptoms usually occurs within what time?
15 minutes to 3 hours after consumption
What percent of Caucasians develop lactose intolerance? African American/Asians?
15% vs 80-90%
Which Wallace kids are intolerant? Which Wallace kids are tolerant?
Ann, David, Dan are intolerant. Nancy and Scott are tolerant.
Explain how some populations that relied on milk as their climate wasn't good to crops may have become lactose tolerant?
Areas where milk was the main food source become lactose tolerant areas where milk was not the main source of food the populations had no pressure from natural selection to adapt their bodies to lactose and they're still lactose intolerant
How can migration and gene flow affect a population?
As populations migrated new genes are introduced into the population which changes the relative Gene frequency of the population. Migration also disrupt the original gene flow.
When the body does not secrete lactase enzyme in the intestine, the lactose sugar is not digested. Bacteria that are a normal part of the colon use the lactose for food and produce gas. How does this contribute to the symptoms of lactose intolerance?
Buildup of gas in an intolerant patient b=produced by bacteria contributes to the gastrointestinal distress
What is a dietary concern for 7/10 African Americans whoa re lactose intolerant?
Calcium deficiency
From which parts of the world did the majority of early American settlers migrate?
Europe- US has low % of lactose intolerance because most European populations had pastoral ancestors
What is the effect of adding lactase enzyme to milk?
Lactase breaks down lactose in the digestive system into glucose and galactose allowing lactose intolerant people to process it
What reaction is catalyzed by the enzyme lactase?
Lactase digests lactose by splitting molecule. Lactose + Water + lactase enzyme= glucose + galactose
Growth factors for __ __ present in human milk may establish and maintain __ __
Lactobacillus bifudus; intestinal flora that are favorable
Equation for Hydrolysis of Lactose:
Lactose + Water = Galactose + Glucose
Parents Mike and Donna Miller are lactose ___.
Lactose Tolerant
Human mother's milk vs cow's milk?
Milk produced by human mammary glands contain about the same % of fat and less protein than cow's milk
How would explain the statistics that approximately 30% of all Americans are lactose intolerant compared to other parts of the world where that number is more than 80%?
Most Americans migrated from populations in Europe which were made up of most lactose absorbers because the people from those regions had pressure from natural selection to adapt to lactose. Meanwhile other countries have seen no such pressure and did not have to make that adaptation to lactose causing the variation of 30% of Americans to 80% and other parts of the world.
Is lactose intolerance an allergy? What is an allergy?
No; allergy associated with hypersensitivity to the protein component of milk
Do animals drink milk for the rest of their lives? Can they?
No; stop drinking after they are weaned; their body chemistry changes so that they can no longer digest the sugar in milk
How does the human body synthesis lactose?
molecule of glucose is converted to galactose, then joined with another glucose molecule
Evolution in Nigeria?
Southern region, where conditions are not favorable for cattle, no milk evolved lactose intolerance. Tribes with cattle are lactose tolerant.
Powdered milk has been shipped to areas of poverty but it causes further malnutrition due to high population of lactose intolerance: T or F
TRUE
T or F the presence of lactose in the colon is beneficial for organisms inhabiting that part of the digestive tract?
TRUE
Which type of sugar is lactose?
disaccharide
Lactase
enzyme that digests milk sugar
What evolution is thought to have produced the modern people who are lactose absorbers throughout adult life?
evolution in pastorall ancestors who kept dairy animals, in populations of Europeans and some Africans
Why is the milk from a mother's breast the best for the infant?
fresh, temperature-controlled, uncontaminated
What component of the disaccharide is not found free in nature
galactose
Equation for lactose? (words)
galactose + glucose = lactose + water
3 other symptoms of lactose intolerance consumption of milk?
gas pains, cramping, bloating
When lactase enzyme is present in sufficient quantity, lactose in the digestive system is broken down into what? (2)
glucose & galactose
Why is milk indigestable by a large majority of the world's population?
in most people the body does not continue to secrete large amounts of enzyme after weaning
Pedigree chart shows?
inheritance of a trait through several generations
If both parents were lactose intolerant the children can be expected to be?
intolerant
Joe and Lucy are lactose ___. Their four children are all __. Name the 4 children?
intolerant/ intolerant- Alicia, Eric, Ben, Rodney
Parent Mary Wallace is lactose __ and her husband John is lactose __.
intolerant; tolerant
What can reduce discomfort by lactose intolerance (2)
knowing what foods cause symptoms and monitoring one's intake of lactose
lactose in digestion-
lactose is digested and absorbed more slowly than other sugars and may improve calcium retention and absorption for increasing the mineral content in bone
Lactose intolerance is a condition that results from..
lactose malabsorption
Primary adult deficiency leads to
lactose malabsorption
Is lactose only in milk?
no in some medications, vitamins, and processed foods
Most African Americans are descendants from? Which makes them lactose what?
non pastoral tribes...lactose intolerant
Primary Adult Lactas Deficiency
normal condition for most people in whom lactose production has practically ceased
Mammalian infants depend on their mother's milk for...
nourishment and immunological protection
What was milk relied on for?
nutrition and food shortages
What does lactose act as to produce diarrhea?
osmotic laxative
Where did lactose tolerance probably first originate?
pastoral ancestors of Europeans and some African nomads who kept dairy animals
Process in which lactose is formed?
polymerization
the age at which lactase declines varies meaning?
presence of lactose in the diet induced the intestinal cells to continue lactase production
Hypothesis
reasoning in which the conclusions are drawn from particular instances or facts
The genetic difference is due to what type of gene?
regulatory gene
For Lactose tolerant people, what dooes milk help with?
strong bones and teeth, and help you grow healthy and tall
Secondary Lactase Deficiency
tempory and the result of a nutritional deficiency or digestive tract disease
What does blood glucose levels depend on?
the absorption of the lactose break down products
What is similar between animals and most humans in milk production?
there is a decline in the level production of lactase with aging
Which milk is tolerated better than skim milk?
whole
