Topic A.1: Components of the Human Diet

1. Topic A.1: Components of the Human Diet Page 208

2. Nutrients • Chemical substance found in foods and used in the human body • Absorbed to give you energy, strengthen bones, prevent you from getting a disease (vitamins) • Some amino acids and lipids can be synthesized by the body, many cannot • So, we get these from foods

3. Essential Nutrients • Nutrients obtained from foods because your body cannot synthesize them • Examples: • Essential amino acids • Essential fatty acids • Minerals • Most vitamins • Water • Carbohydrates are not essential nutrients b/c it is possible to live on diets with little to no carbohydrates • Not highly advised …

4. Amino Acids • 20 amino acids  proteins • Nine of these amino acids cannot be synthesized in the body • The human genome lacks the DNA sequence • Referred to as essential amino acids • The other 11 can be manufactured in the body; called nonessential amino acids

5. Protein Deficiency • Deficiency • A person is not getting enough of a certain nutrient • This causes a health problem • Protein deficiency • Can lead to insufficient production of blood plasma proteins • Retention of fluids in certain tissues • Notably the walls of the intestine • Example of malnutrition

6. Malnutrition • Imbalance in the diet which leads to one or more diseases • Typically caused by a deficiency; in some circumstances, caused by an excess of one or more essential nutrients • Example: Kwashiorkor Disease • Common in children in non-industrialized countries • Name comes from Ghana • A second born child receives milk from his mother, but leaves little to no milk for the first born • First born may develop Kwashiorkor (protein deficiency)

7. Kwashiorkor • Symptoms include: • Fatigue, growth failure, loss of muscle mass edema, decreased immunity • Complications: • Coma, shock, permanent mental and physical disability

9. A Simple Cure … ? • Eat more protein • However, sources of protein are expensive • Not an easy option for many families • Humanitarian efforts • High protein biscuits • Teach people how to raise chicken • Introduce eggs into diets

10. A Place at the Table

11. Turn and Talk • To what degree do you think the following are factors in malnutrition? • Poverty and wealth • Cultural differences concerning dietary preference • Climatic conditions • Poor distribution of food (i.e. insufficient roads, bridges, railways) • A nomadic lifestyle • Corrupt politicians misusing agriculture or aid money • Lack of health care leading to a cycle of disease and poverty

12. PKU • Genetic disease caused by a mutated gene • The gene codes for a specific enzyme which converts the amino acid phenylalanine to tyrosine • People with PKU cannot convert phenylalanine into tyrosine, so they have very high levels of phenylalanine • This affects brain development • Untreated PKU  severe mental problems and learning difficulties

13. Solution • PKU can be diagnosed early with a blood test at birth • Parents can be informed what treatment if necessary • Common to follow a diet low in protein to avoid phenylalanine (eliminate milk, peanuts, cheese, meat) • Aspartame contains phenylalanine (one reason to label all food products)

14. Fatty Acids • Not all fats are created equal • What is the same: • Carboxyl group (COOH) • Methyl group (CH3) • Hydrocarbon tail (in the middle) • See figures on pages 210-211 • 7.1, 7.2, 7.3

15. Saturated Fatty Acids • Saturated with hydrogen atoms • No double bonds between the carbon groups • The shape is straight – no kinks • Animal products: • Bacon, butter, fat in red meat • Generally solid at room temperature • Eat in extreme moderation …

16. Monounsaturated Fatty Acids • If one double bond exists in the chain of hydrocarbons, the fatty acid is NOT saturated • Monounsaturated fatty acids • Two or more double bonds … • Polyunsaturated fatty acids • Typically comes from plants • Olives, avocados, nuts • Tend to be liquid at room temperature

18. Cis vs. Trans fatty acids • In some processed foods (snacks, cake), polyunsaturated fats are hydrogenated • This means the double bonds are eliminated by adding hydrogen atoms • Straightens out the natural bent shape • Naturally curved fatty acids are called cis • The hydrogenated fatty acids are called trans • AVOID TRANS FATS!!

19. Omega 3 Fatty Acids • Example of cis fatty acids • Healthy • Good for your brain and heart • Salmon, sardines, mackerel (fish)

20. Diets rich in fats • The shape is important • Fatty acids that are curved are more easily picked up in the current of the blood stream • Straight fatty acids can lie flat against the walls • Deposits combine with cholesterol to form plaque • Inner lining of blood vessels

21. Plaque • Reduces blood flow • A chunk may break off, get lodged, so no blood can pass through • If this happens in the heart (heart attack) • If this happens in the brain (stroke)

23. Heart Attacks & Diet

24. So, about eating fats • A diet rich in saturated fats has a much higher chance of leading to serious cardiovascular problems later in life • Diets rich in polyunsaturated fats lead to lower quantities of plaque • Also tend to carry cholesterol away • Both types have high amounts of energy (CALORIES), so consuming a lot of either type is unhealthy

25. So, take away message • When you eat, look at the food labels • Look for cholesterol, saturated fatty acids, polyunsaturated acids, and trans fat • Your body needs healthy fat to function, but focus on eating a balanced diet • Cardiovascular disease is also influenced by genetics, amount of exercise, and smoking

26. Vitamins and minerals • Often grouped together, but structurally very different • Minerals are inorganic • Does not contain carbon • Not synthesized by organisms • Rocks, soil, or sea water • Vitamins are organic • Synthesized in plants and animals • Contain carbon

27. Examples • Minerals: • Sodium, calcium, iron • Vitamins: • Vitamin A, C, D, ... • Both are needed in very small amounts (we’re talking milligrams) • Both prevent dificiency diseases

28. Vitamin C • Recommended level 30-60 mg per day • Check your food labels • Vitamin C protects against infection, wound healing, and maintaining healthy gums, teeth, bones and blood vessels • Excess vitamin C can lead to kidney stones • Too little vitamin C can cause scurvy • Fluid retention, loss of teeth, bleeding into joints, and anemia • Untreated may be fatal

29. Vitamin D • Formation of bones • Insufficient supply of vitamin D may cause rickets. • Deformities in the bones • Children with rickets do not reach optimal height; legs are often bowed inward or outward at the knees (see picture on page 216)

30. Vitamin D • Sources: • Exposure to sunlight • Food (fish: salmon, tuna, sardines; eggs, liver, milk and cereal are often fortified) • Vitamin supplements • Risks? • Exposure to sun  UV radiation (may cause sunburn and skin cancer called malignant melanoma)

31. Dr. Oz & Vitamin D

32. Dietary Supplements • May be taken if the foods you eat do not provide you with vital minerals and nutrients

33. Iodine • Iodine is a component of thyroxin, a hormone made by the thyroid gland • Regulates growth • Too little iodine  inflammation of the thyroid gland • This is called a goiter • Babies may suffer from growth and mental retardation

34. Why don’t we see a lot of goiters in industrialized countries? • Iodine is added to salt • US; 1924 • By the 1950s, goiters were essentially nonexistent in the US

35. Fiber • “Roughage” – provides bulk • Cellulose in plant material • Reduces likelihood of constipation and chances of intestinal problems like colon cancer • Also links to reduced cardiovascular disease • Toxins bind to fiber and carried out of the body • Links to managing body mass  fiber helps you feel fuller longer • Many people do not get the amount of fiber they need on a daily basis.

36. Take away message • So what are some of the foods you should be eating? Why? • What are foods you should avoid, or eat in moderation? Why?

37. Take away message, from Dr. Oz