Human Nutrition

1. Human Nutrition (Cambridge Biology Chapter 4)

2. First of all… • Why do we need to eat? • Why do we need to eat a balanced diet?

3. Nutrition is: • From Latin: “nutrire” = “nourishing” • Obtaining organic substances and mineral ions from which organisms obtain their energy and raw materials for growth and tissue repair.

4. 6 Types of Nutrients • Carbohydrates • Proteins • Fats • Vitamins • Inorganic Ions (“Minerals”) • Water

5. Organic vs. Inorganic Nutrients Organic Inorganic No Carbon Typically “stand-alone” substances. For example: Salt (mineral of NaCl) • Molecules contain Carbon • Typically components of plant or animal tissues. • For example: Pepper (ground plant fruits)

6. Organic or Inorganic? • Sugar • Iron • Wood • Water • Oxygen • Alcohol • O • I • O • I • I • O

7. Why Do Humans Need Nutrients? • To give us ENERGY! • We need energy for heat, movement, and chemical reactions in our bodies. • Carbs + Fats. • To give us Building Materials: • We need to build the cells in our bodies. • Proteins.

8. Why Else? • To give us Chemicals for Reactions • We need chemicals to make chemical reactions take place in our bodies. • Proteins, vitamins, minerals, and water.

9. Carbohydrates • Carbo = carbon • Hydrate = water = hydrogen and oxygen • So “carbs” are molecules of C, H, and O.

10. I bet you can do this… • What’s a saccharide? • A monosaccharide? • A disaccharide? • A polysaccharide? • “sugar” • “one sugar” • “two sugars” • “many sugars”

11. Simple Sugars: Monosaccharides • A single ring of C, O, and H. • Glucose (yum!)  • Fructose • Galactose

12. Complex Sugars: Disaccharides • Two sugar rings linked together. • Glucose + • Galactose = • Lactose

13. Complex Sugars: Polysaccharides • 3 Types: • Cellulose • Makes up plant cell walls • Starch • Stored as food reserve in plant cells • Glycogen • Stored as food reserve in animal liver and muscle cells

14. Cellulose

15. Starch

16. Glycogen (in liver cells)

17. Why do we need Carbs? • One reason: Energy! • Plants take energy from the Sun, and turn it into carbohydrates. • Animals eat plants and use the energy to do work (survive). • Extra carbohydrates are changed into Fat.

19. What is a Low-Carb Diet? • Low-carbohydrate diets restrict caloric intake by reducing the consumption of carbohydrates to 20 to 60 g per day (typically less than 20 percent of the daily caloric intake). The consumption of protein and fat is increased to compensate for part of the calories that formerly came from carbohydrates. • … but what are calories?

20. Calories • Energy in food is measured in Calories. • Average need is 2,000 calories per day. • Carbs have lots of energy (lots of calories). • Going on a low-carb diet means you get less energy out of your food. • Is that a good idea?

21. Proteins • A long molecule made of smaller molecules called amino acids.

22. Amino Acids • There are only 20 different amino acids. • They can be linked in any order. • A protein’s “identity” is based on the number and order of amino acids.

23. Amino Acids

24. Protein Chains

25. Protein Molecules

26. Where Do We Get Proteins? • We make them from amino acids. • When we eat proteins, the molecules are chopped up into amino acids. • Then we put them back together to make the proteins we need.

27. Sources of Proteins

28. Why Do We Need Proteins? • Building Blocks for our cells: • Cell membranes • Muscle: for cells to produce movement • Bones/Skin: Collagen • Hair/Nails: Keratin

29. Keratin

30. Proteins are also… • Enzymes! (remember those?) • Help chemical reactions take place • Hemoglobin • Red stuff in our blood; carries Oxygen • Antibodies • Attack bacteria and viruses • Hormones – like Insulin • Energy – but not usually

31. Hemoglobin

32. Amino Acids in Food • Nonessential AA’s • Our body can make them on its own. • Essential AA’s • Body can’t make them; they must come from foods we eat. • Meat, milk, and eggs contain all the essential amino acids we need. • Fruit, grains, and vegetables contain only some.

33. What about Vegetarians? • They just have to make sure they get all the essential amino acids from a diet that includes a lot different kinds of foods, especially grains and legumes (beans, etc.)

34. Fat • One Fat molecule is made of: • 1 molecule of Glycerol • 3 fatty acids

35. Sources of Fat From Animals From Plants Peanut Oil Olive Oil Corn/ Vegetable Oil Unsaturated Fats • Lard (pig fat) • Fish Oil • Butter (from milk) • Saturated Fats

36. Saturated vs. Unsaturated Fats

37. Why Do We Need Fats? • Energy! • We can use it or store it. • Fat contains more energy than carbohydrates. • 1 gram of Fat = 2x the energy in 1 gram of Carbs • Cell Membranes • Heat Insulation

38. Fat as Insulation

39. Vitamins • Organic substances that we only need in very small amounts in our diet.

40. Vitamin C

41. Vitamin C • Helps make the protein Collagen. • Collagen is part of bones, skin, and blood vessels. • Without Vitamin C, skin and blood vessels become weak due to lack of Collagen. • Without enough Vitamin C, you can get a disease called Scurvy! • Bruises and ulcers on skin; weak gums

42. Scurvy

43. Vitamin D

44. Vitamin D • Helps us absorb Calcium from food to make bones and teeth. • We can eat it from both plants and animals. • We can also make it when we get enough sunshine. • Without enough Vitamin D, you can get a disease called Rickets! • Bone is soft and grows into bent shapes

45. Rickets

46. Vitamin A • Helps with a LOT of functions in the body. • Without enough Vitamin A, impaired vision or blindness can occur.

47. Vitamin A

48. Inorganic Ions • Sometimes called Minerals. • We only need them in small amounts.

49. Iron • Helps us make Hemoglobin. • Makes our blood red! • Carries Oxygen in our blood. • Without enough Iron, you can get a disease called Anemia! • Feel tired very easily

50. Iron in Blood