Feeding The World

Human Nutrition

- Humans are omnivores- Nutrients are divided into two main categories:

- Macro and Micronutrients- Macronutrients: provide body with energy- Measured in units called kilocalories (kcal)- A kilocalorie provides enough energy to raise the

temperature of one kilogram of water one degree Celsius.

- We usually just refer to these as Calories in the real world, i.e. food labels.

- Generally speaking the amount of calories found in food indicates how much energy the food provides.- The three types of macronutrients are, carbohydrates, proteins, and fats.- The USFDA (US food and drug administration) provides nutritional guidelines, in a typical looking pyramid.

The Big 3 macronutrients:

Carbohydrates- 1:2:1 ratio of carbons, hydrogens, and oxygens- Also know to us as “sugars”- Simple sugars are absorbed easily, complex are not and must

be broken down first- Sugars are broken down in the process of cellular respiration- Typically 4kcal per gram of sugar is available to the body.- Foods high in sugar: fruits, vegetables, bread, grains, (good

sugars) and deserts (bad sugars)

Proteins- Large compounds made of amino acids, or the building blocks of

everything!!- Based on nitrogen (remember the nitrogen cycle?)- Provide ab out 4kcal of energy, but not suggested as a good source for

obtaining energy.- 20 different amino acids, make up everything- Only 12 can be made by the human body the others must be

obtained from foods (called essential amino acids)- Problems with vegetarians:

- Most food from animals will provide all 8 EAA’s- Plants lack many, so combinations must be consumed to get all 8.

Fats- Also called lipids: long chains of fatty acids attached to a molecule of

glycerol- Phospholipids contain a phosphate group- Solids lipids are typically called fats- Liquid lipids are typically called oils- Provide 9kcals of energy per gram.- Saturated fats

- Firm at room temp- Most animal fats are highly saturated- Straight line bonds

- Unsaturated fats- Typically liquid at room temp- Most plant oils are highly unsaturated

Fats continued:- Monounsaturated and polyunsaturated are also seen, basically a

difference in their molecular structure.- Hydrogenated fats are liquid vegetable oils where hydrogens have

been added.- Saturated fats are typically the ones that contribute the most to

heart disease.Vitamins and minerals- Micronutrients- Do not provide direct energy, rather play key roles in the biochemical

reactions that release energy.- All can be obtained from food directly.- Unfortunately many are removed via improper cooking techniques,

or processing.

Nutritional deficiency- Typically the human diet should consist of 2000 to 2800 kcal

per day (depends on activities and such).- Less than 90 % per day constitutes undernourished. - Less than 80% per day constitutes seriously undernourished.- Estimated 800 million (probably more since book is so old) are

undernourished, and 500 million are chronically hungry.- Malnutrition is the lack of a specific type of nutrient (not

necessarily starvation).- Kwashiorkor (KWAH-shee-OR-kor) is a deficiency disease

caused by too little protein in an otherwise adequate diet. Bloated belly is one sign.

World food supplyThe Green revolution- Mid 1960’s with the development of wheat and rice (two main foods of the

world)- New varieties were very responsive to fertilizers and irrigation- Called “miracle” plants, drought and disease resistant- Also introduction of modern farming methods and tools- Products of this were huge amounts of food with less amounts (or same

amount) of land- Was typically not available in areas where food was needed the most though- Good for developed nations- Not viable for developing nations- Negative: drove down the price of grains, therefore small farms couldn’t afford

to stay in business.

Cash Crops- Crops that is grown for the purpose of sale

Food from water- Aquaculture is the commercial production of fish in a

controlled, maintained environment.- Alternative to commercial fishing, suspected to be more

sustainable- Fresh or saltwater- Asia is the leading area for fish farms

Industrialized agriculture- 1950 half a barrel of oil is used per ton of grain, by

1985, it is doubled- Highly efficient and productive at getting a product- However, requires huge amounts of energy, pesticides,

and fertilizers- Often run by corporations (called agribusinesses)- They also often control all the stages of production as

well, growing , packing and transporting

Continued:- Pesticides are great, for the farmers, not so great for

everything else- Pests develop resistance and become more of a problem- Runoff can cause problems for creeks and rivers, and then

for the fish, etc…- Monoculture: growing only one specific type of crop.

- Good, use the same things on entire crop (pesticides fertilizers etc..)

- Bad, everything is susceptible, i.e. one disease will wipe out entire crop- Depletes the soil much quicker

Sustainable agriculture: based on crop rotation, reduced soil erosion, integrated pest management (IPM), and minimal use of soil additives.

- erosion: careful irrigation, soil management, drip irrigation, less tilling vs intensive tilling.- Pest management, IPM: can help reduce pesticides for example: makes use of natural predators, wasps, ladybugs.