NU FS 223: MODULE 5,6,7

lactose

milk sugar lactose —> prime source of carbohydrates for all young mammals, inculding human infants

digestion of lactose

lactase hydrolyzes lactose into glucose and galactose.

lactase non-persistence (intolerance)

• continued production of lactase after childhood is a genetically determined trait

• the inability to digest lactose occurs in adulthood (adults are lactose intolerant)

• phenotype is homozygous and received 2 copies of the low lactase-activity allele 

what happens if you cannot digest lactose

• lactose fermented by bacteria in the colon: produces gases such as CO2, methane, hydrogen 

• lactose osmotically attracts fluid into bowel lumen: DIARRHEA

lactase persistence (tolerance)

• genetically programmed continued activity of the lactase enzyme into adulthood

• dominant trait

I can drink a glass milk without any unpleasant side effects

non-muntant

if i drink a glass of milk I have unpleasant side effects

mutant

lactose tolerance

the prevalence of lactose tolerance is highest in populations with long history of cosuming milk products

gene culture coevolution hypothesis

pastoralism —→ lactase persistence and vice versa. They are related to each other

bacterial fermentation of milk products

• there is evidence that fermented ilk produects (yogurt, cheese) have been produced since around 10,000 BCE 

• individuals may lack the allele for lactase persustence but can still tolerate dairy products in which lactose is broken down by lactic acid fermentation process

• lactic acid bacteria ferment lactose to produce lactic acid

calcium for skeletal integrity

• important mineral for skeletal integrity

• over 99% of body calcium is calcium hydroxyapatite in bones and teeth

• teh bioavailability of calcium is an important factor to consider beyond simple the calcium content of food

other needs for skeletal integrity

• vitamin D —> increases calcium absorption in small intestine and kidney and increase bone mineralization

• protein

other reasons to consume milk and dairy products 

• relatively clean liquid 

• multiple nutrients (vitamins A,D, B12, riboflavin, calcium, phosphorus) 

• energy, fat 

• rather than killing animals for meat, you milk them

ethanol

• known as ethyl alchohol or drinking alcohol

• is a toxin and a CNS depressant

alcohol metabolism

• the key liver enzymes involved are alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH)

• ADH catalyzes the oxidation of ethanol into acetaldehyde.

• Acetaldehyde is then oxidized to non-toxic acetate (acetic acid) by ALDH.

steps in oxidation of alcohol

1. ethanol —→ acetaldehyde 

2. acetaldehyde —> acetate 

3. acetate —→ CO2 + H2O

alcohol intolerance

genic polymorphisms may prevent alcohol addiction

• new gene variants arise and sprea across populations if they have a reproductive advantage

• heavy drinkers may not leave as many offspring

• genetic polymorphisms is ADH and ALDH may protect against alcoholism

• ALDH variants may protect againts alcoholism in East Asia

• Variants of ADH may protect against alcoholism in Asia and Africa

ALDH2 variant

• reduction in the capacity of acetaldehyde clearance leads to accumulation of acetaldehyde in circulation

• prevalent among northieastern Asian populations (China, Taiwan, Japan, Korea)

• causes the asian alcohol flushing syndrome characterized by facial flushing, tachycardia (rapid heartbeat), nausea, and unpleasant feelings when alcohol is consumed

• alcohol flushing and its associated unpleasant feelings due to acetaldehyde accumulation is often a strong deterrent against heavy drinking

alcohol flush reaction

• red flushes or blotches on the face, neck, shoulders afterr consuming alcohololic beverages 

• due to an accumulation of acetaldehyde in ALDH-deficient individuals

disease risk

ALDH2 deficient populations may be more susceptible to the carcinogenic effect of consuming alcohol with most evidence coming from studies of esophageal cancer and head and neck cancer

why do asians with the variant allele continue to drink

• Heterozygotes can develop tolerance to acetaldehyde and the flushing response and can become habitual heavy drinkers.

• In Korea, Japan and China, it is important, especially for men, to socialize and drink heavily, which may result in acceptance of heavy drinking and alcohol problems.

• Economic growth and increasing social openness in China over the last 30 years have increased alcohol consumption, and consequently,the incidence of alcoholic liver disease in China has increased

canivore

only eats animal flesh like red meat, poultry, or fish

omnivore

eats plants and animal flesh (may eat eggs and dairy)

plant-based diets

foundation of the diet is plants (grains, fruits, veggies)

• pescatarian (fish)

• mediterranean diet

• semi-vegetarian diet

• felxitarian diet

vegan 

those who eat plants only NO animal flesh, eggs, or diary

ovo-vegetarian

those who eats eggs in addition to plants

lacto-vegetarian 

those who eat dairy in addition to plants (buddhists, hinduism, some skihs)

lacto-ovo vegetarians

those who eat eggs and diary in addition to plants

east and southeast asian vegetarian foods 

seitan (wheat gluten), tofu (soybean curd), and tempeh (fermented soybeans) 

• many vegetarian diets in these cultures do not contain dairy 

vegetarianism among youths

6.6% vegetarian, 4.5% pescatarian, and 2.5% vegan

problems with meat free diets

• diets that are plant-based and contain whole foods have health benefits

• diets with minimal dietary diversity or many highly processed foods are unhealthy

planetary health diet 

• a healthy diet should optimise health, defined broadly by WHO as being a state of complete physical, mental, and social wellbeing, and not just absence of disease

• a sustainable diet should minimize climate change, biodiversity loss, land-system change, freshwater use and use of nitrogen and phosphorus fertilizer. 

planetary plate

• 50% fruits and vegetables

• 50% whole grains, plant protein sources (beans), unsaturated oils, moderate amounts of animal proteins

• consume more plant-based protein