2 Human NutritionHumans are omnivoresNutrients are divided into two main categories:Macro and MicronutrientsMacronutrients: provide body with energyMeasured 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.
3 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.
4 The Big 3 macronutrients: Carbohydrates1:2:1 ratio of carbons, hydrogens, and oxygensAlso know to us as “sugars”Simple sugars are absorbed easily, complex are not and must be broken down firstSugars are broken down in the process of cellular respirationTypically 4kcal per gram of sugar is available to the body.Foods high in sugar: fruits, vegetables, bread, grains, (good sugars) and deserts (bad sugars)
5 ProteinsLarge 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 everythingOnly 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’sPlants lack many, so combinations must be consumed to get all 8.
6 FatsAlso called lipids: long chains of fatty acids attached to a molecule of glycerolPhospholipids contain a phosphate groupSolids lipids are typically called fatsLiquid lipids are typically called oilsProvide 9kcals of energy per gram.Saturated fatsFirm at room tempMost animal fats are highly saturatedStraight line bondsUnsaturated fatsTypically liquid at room tempMost plant oils are highly unsaturated
7 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 mineralsMicronutrientsDo 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.
8 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.
9 World food supplyThe Green revolutionMid 1960’s with the development of wheat and rice (two main foods of the world)New varieties were very responsive to fertilizers and irrigationCalled “miracle” plants, drought and disease resistantAlso introduction of modern farming methods and toolsProducts of this were huge amounts of food with less amounts (or same amount) of landWas typically not available in areas where food was needed the most thoughGood for developed nationsNot viable for developing nationsNegative: drove down the price of grains, therefore small farms couldn’t afford to stay in business.
10 Cash CropsCrops that is grown for the purpose of saleFood from waterAquaculture is the commercial production of fish in a controlled, maintained environment.Alternative to commercial fishing, suspected to be more sustainableFresh or saltwaterAsia is the leading area for fish farms
11 Industrialized agriculture 1950 half a barrel of oil is used per ton of grain, by 1985, it is doubledHighly efficient and productive at getting a productHowever, requires huge amounts of energy, pesticides, and fertilizersOften run by corporations (called agribusinesses)They also often control all the stages of production as well, growing , packing and transporting
12 Continued:Pesticides are great, for the farmers, not so great for everything elsePests develop resistance and become more of a problemRunoff 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 cropDepletes the soil much quicker
13 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.