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

Molecules of Food: Carbohydrates

6-C rings, 5-C ringsMono-saccharides (sugar, fructose)

Dissacharides (lactose, sucrose) Polysaccharides (starch, fibre, glycogen)

Carbohydrates are assimilated in the body as “mono-saccharides” following digestion

Glucose: Body’s Primary Fuels

Glycogens

(Branched polymers for short-term storage

in liver)

Glucose

(monomers) (soluble)

Lactic Acid + ATP + H2O

(anaerobic)

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

Glycogen

Anaerobic Metabolism

Aerobic Metabolism

Pyruvic Acid CO2 + H20 + 32ATP

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

Free Fatty Acids (one chain)

• Saturated• Unsaturated (e.g. Omega-3, Omega-6)

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)

Triglycerides

Phospholipids

• Phospholipids are “modified” triglycerides where one fatty acid chain is replaced by a phosphate group

• Soluble in water

• Important in cell membrane

Phospholipids

Sterols

• Multiple rings of carbon

• Best-known sterols: cholesterol (the building block for all other sterols)

• Bile acids, some hormones, Vitamin C

Sterols

Cholesterol Sitosterol (the most abundant and common plant

sterol)

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

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

Amino Acids

• Four components around a central carbon (C)

• One hydrogen• An amino group (-

NH2)

• An acid (-COOH)• A functional group

Glycine

Essential Amino Acid: Leucine

Non-essential Amino Acid: Asparagine

Amino Acids

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

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

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.

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.

Example of Subsistence Food Economy

Inupiat households in Barrow, Alaska

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

Body Part Meat Skin Head Eggs

Excellent Source

(25% or more of

daily need)

Protein, Iron Protein, Iron, Calcium, Fat

Protein, B Vitamins

Protein, Vitamin C, Fat, Iron, B Vitamins

Good Source (15-

24% of daily need)

B Vitamins Calcium

Fair Source (5-14% of daily need)

Vitamin C Vitamin A, Fat, Iron

Calcium

Quality Food: Arctic Char

Quality Food: Beluga

Body Part Meat Blubber Skin

Excellent Source (25% or

more of daily need)

Iron, Protein Fat Protein

Good Source (15-24% of daily need)

Protein, Omega-3 fatty acid

Fair Source (5-14% of daily

need)

Fat Iron Fat, Vitamin A

Quality Food: CaribouBody Part Meat Blood Liver Bone

MarrowStomach Contents

Fat

Excellent Source (25%

or more of daily need)

Protein Iron Protein, Iron,

Vitamin A

Fat

Good Source (15-24% of daily need)

Iron, B Vitamins

Protein Iron, Fat Iron, Vitamin A

Iron

Fair Source (5-14% of daily need)

Fat, Calcium

B Vitamins

Fat, Calcium

Protein, Fat, Vitamin A

Protein, Fat, B

Vitamins, Calcium

Protein

Quality Food: Muskox

Body Part Meat

Excellent Source (25% or

more of daily need)

Protein, Iron

Good Source (15-24% of daily need)

B Vitamins

Fair Source (5-14% of daily

need)

Vitamin C

Quality Food: Polar Bear

Body Part Meat Blubber

Excellent Source (25% or more of

daily need)

Iron, Protein Vitamin A, Fat

Good Source (15-24% of daily need)

Omega-3 fatty acid

Fair Source (5-14% of daily need)

Fat Iron, Protein

Quality Food: Ring Seal

Body Part

Intestine Liver Blubber Meat Brain Eyes

Excellent Source

(25% or more of

daily need)

Protein Iron, Protein,

Vitamin A

Fat, Vitamin A, Omega-3 fatty acid

Iron, Protein, B Vitamins

Iron, Protein

Vitamin A, Protein,

Iron

Good Source

(15-24% of daily need)

Iron Vitamin C Iron, Vitamin C

Fat

Fair Source (5-

14% of daily need)

Fat Fat Protein Fat

What is special about a subsistence diet in the North?