metabolism

1. Module 8: Food Chemistry,
Nutrition, and Traditional Foods
Food: Any substances that can be metabolized
by an organism to give energy and build
tissue
Types: Carbohydrates, Proteins, Fats & Oils
Others: Vitamins, Minerals, Salts

2. Molecules of Food: Carbohydrates
6-C rings, 5-C rings
Mono-saccharides (sugar, fructose)
Dissacharides (lactose, sucrose)
Polysaccharides (starch, fibre, glycogen)
Carbohydrates are assimilated in the body
as “mono-saccharides” following digestion

4. Glucose: Body’s Primary Fuels
Lactic Acid + ATP + H2O
Glycogens Glucose (anaerobic)
(Branched polymers (monomers)
for short-term storage (soluble)
in liver) Pyruvic Acid  CO2 + H20 + ATP
(aerobic)
•Glucose level in blood stream is highly regulated
•Aerobic respiration is releasing 90% of the energy stored in
glucose

5. Glycogen

6. Anaerobic
Metabolism
Aerobic
Pyruvic Acid  CO2 + H20 + 32ATP
Metabolism

7. Molecules of Food: Lipids and Fats
Fats: Large biological molecules, diverse
compositions, insoluble in water (i.e. non-polar in
nature)
Types:
– Fatty acids (assimilable form)
– Triglycerides (in blood)
– Phospholipids (cell membranes)
– Sterols (e.g. cholesterol)
Roles:
– Source of energy (during sustained activity)
– Structure of cell membrane

8. Free Fatty Acids (one chain)
• Saturated
• Unsaturated (e.g. Omega-3, Omega-6)

9. Fatty Acids
• Long-chain fatty acids (12+ carbons) are abundant
in meats and fish
• Short-chain fatty acids (12 carbons or less) are
abundant in dairy products
• Cold-water fish are rich in essential omega fatty
acids
• Unsaturated fatty acids, when cooked, change
conformation to a “trans” shape (which tend to
accumulate in blood vessels)
• Unsaturated fats are more prone to react with
oxygen, causing rancidity (common in stored fish)

10. Triglycerides

11. Phospholipids
• Phospholipids are “modified” triglycerides
where one fatty acid chain is replaced by a
phosphate group
• Soluble in water
• Important in cell membrane

12. Phospholipids

13. Sterols
• Multiple rings of carbon
• Best-known sterols: cholesterol (the
building block for all other sterols)
• Bile acids, some hormones, Vitamin C

14. Sterols
Cholesterol Sitosterol (the most
abundant and common plant
sterol)

15. Absorption of Lipids
• Fat breakdown occurs in intestines
• Smaller units: fatty acids, glycerol, and
sterols
• Cholesterol and triglycerides are non-polar,
hence need “lipoproteins” to carry them in
the bloodstream

16. Molecules of Food: Proteins
• Chains of Amino Acids
• Diverse roles: enzymes, hormones,
regulators, molecular transports, antibodies,
building tissue like muscles, and energy
• Made up of C, H, O, N, other ions

17. Amino Acids
• Four components
around a central
carbon (C)
• One hydrogen
• An amino group (-
NH2)
• An acid (-COOH)
Glycine
• A functional group

18. Amino Acids
Essential Amino Non-essential
Acid: Leucine Amino Acid:
Asparagine

19. Molecules of Food: Vitamins
• Essential organic compounds to ensure
proper metabolism
• Little caloric value
• Water-soluble vitamins (enter directly into
bloodstream)
• Fat-soluble vitamins (must be transported
by carrier proteins)
• Several diseases are associated with vitamin
deficiencies

21. Caloric Contents of Food Molecules
Food Type Caloric %
Content (Cal/g) Recommended
Caloric Intake
Fats and Oils 9 30
Carbohydrates 4 58
Proteins 4 10
Vitamins Trace Not Applicable

22. Subsistence Food Provisioning
• Nutrition for indigenous people in the Arctic is
changing rapidly; from 100% to <50% “country
food”.
• Presence of larger communities, presence of “Co-
op” or “Bay” stores, and an increasing cash
economy contribute to changes in feeding habits.
• Lastly, hunting activities are costly when modern
technologies are used  the “pay off” of
traditional food provisioning is decreasing.

23. Concepts
Subsistence activities: The hunting, fishing, and
gathering of local foods for consumption, sharing,
and trade or barter.
e.g. caribou, whales, seals, marine birds, waterfowls,
eggs, fruits (largely a carnivore diet)
Note: Commercial trapping or fishing is generally
not viewed as traditional food gathering; although
they could be traditional activities.

24. Example of Subsistence Food
Economy
Inupiat households in Barrow, Alaska

29. Production vs. Sharing
• Food provisioning is crucial, but sharing is
an intricate part of subsistence
• Sharing touches upon all members of a
community, and represents a way of
establishing and maintaining ties to family
and within the community at large (e.g.
support of elders, non-hunting members)
• Sharing is viewed as part of the “culture” of
indigenous society

30. Quality Food: Arctic Char
Body Part Meat Skin Head Eggs
Excellent Protein, Iron Protein, Iron, Protein, B Protein,
Source Calcium, Fat Vitamins Vitamin C,
(25% or Fat, Iron, B
more of Vitamins
daily need)
Good B Vitamins Calcium
Source (15-
24% of
daily need)
Fair Source Vitamin C Vitamin A, Calcium
(5-14% of Fat, Iron
daily need)

31. Quality Food: Beluga
Body Part Meat Blubber Skin
Excellent Iron, Protein Fat Protein
Source (25% or
more of daily
need)
Good Source Protein, Omega-
(15-24% of 3 fatty acid
daily need)
Fair Source (5- Fat Iron Fat, Vitamin A
14% of daily
need)

32. Quality Food: Caribou
Body Part Meat Blood Liver Bone Stomach Fat
Marrow Contents
Excellent Protein Iron Protein, Fat
Source (25% Iron,
or more of Vitamin
daily need) A
Good Source Iron, B Protein Iron, Fat Iron, Iron
(15-24% of Vitamins Vitamin A
daily need)
Fair Source Fat, B Fat, Protein, Fat, Protein, Protein
(5-14% of Calcium Vitamins Calcium Vitamin A Fat, B
daily need) Vitamins,
Calcium

33. Quality Food: Muskox
Body Part Meat
Excellent Protein, Iron
Source (25% or
more of daily
need)
Good Source B Vitamins
(15-24% of
daily need)
Fair Source (5- Vitamin C
14% of daily
need)

34. Quality Food: Polar Bear
Body Part Meat Blubber
Excellent Source Iron, Protein Vitamin A, Fat
(25% or more of
daily need)
Good Source (15- Omega-3 fatty acid
24% of daily need)
Fair Source (5-14% Fat Iron, Protein
of daily need)

35. Quality Food: Ring Seal
Body Intestine Liver Blubber Meat Brain Eyes
Part
Excellent Protein Iron, Fat, Iron, Iron, Vitamin A,
Source Protein, Vitamin A, Protein, B Protein Protein,
(25% or Vitamin A Omega-3 Vitamins Iron
more of fatty acid
daily need)
Good Iron Vitamin C Iron, Fat
Source Vitamin C
(15-24% of
daily need)
Fair Fat Fat Protein Fat
Source (5-
14% of
daily need)

36. What is special about a
subsistence diet in the North?