Components of the Human Diet

1. Components of the Human Diet By Josh Negrit and Alexandre Duguay

2. Assessment Statements • Distinguish between minerals and vitamins in terms of their chemical nature • Outline two of the methods that have been used to determine the recommended daily intake of vitamin C • Discuss the amount of vitamin C that an adult should consume per day, including the level needed to prevent scurvy; claims that higher intakes give protection against upper respiratory tract infections; and the danger of rebound malnutrition • List the sources of vitamin D in human diets • Discuss how the risk of vitamin D deficiency from insufficient exposure to sunlight can be balanced against the risk of contracting malignant melanoma • Explain the benefits of artificial dietary supplementation as a means of preventing malnutrition, using iodine as an example • Outline the importance of fiber as a component of a balanced diet

3. Vitamins and Minerals

4. So why are minerals and vitamins always grouped together? • Because they are both needed in small quantities • Also because they both prevent deficiency diseases

5. How much vitamin C do we need? • Two ways to determine this: • Animal testing • and testing on human subjects

6. Animal Testing • Carried out on laboratory mice • Aim is to feed varying amounts of vitamin C to several groups of mice • Everything is the same in their diets except the amount of vitamin C • Health of mice is compared after a certain time • Those with insufficient levels are expected to be more prone to infections and illnesses. • Those with sufficient levels would be healthy • Those with levels of vitamin C too high, will have undesirable side effects.

7. Human Testing • Presents many ethical questions • Experimentation is done with consenting volunteers who sign a contract acknowledging that they are aware of the potential risks • Same process from the mice applies to the human experimentation

8. Minimum intake of vitamin C • To prevent scurvy (a deficiency disease), to protect against upper respiratory tract infections, and to prevent undesirable side-effects (such as diarrhea), it is recommended to consume around 30mg to 60mg of vitamin C

9. Vitamin D • Sources in our diets: • Salmon • Tuna • Sardines • Eggs (vitamin D is in the yolk) • Many ready-to-eat breakfast cereals are fortified with vitamin D • Liver • Milk is often fortified with vitamin D (especially in the U.S.)

10. Balancing two Risks • Without exposure to sun, there is less intake of vitamin D, due to reduced synthesis of vitamin D • Too much exposure to sunlight leads sunburns, and after many years, skin cancer, which is called malignant melanoma • What is wanted is a balance between the two • It is not needed to be outdoor for very long • If exposure to sunlight is to be extended, the use of sunblock can protect the skin, while maintaining the synthesis of vitamin D in your body

11. Artificial Dietary Supplements? Yes? Or No? • Iodine, a component of thyroxin, a hormone made by the thyroid gland, is rich in areas near sea water • For instance, in places near the shore where eating seafood and kelp on a regular basis allows for people to not have a deficiency in iodine • But in places far from the shore, the access to regular seafood put people in risk of not getting enough iodine • This can lead to the inflation of the thyroid gland, which is called goitre • Babies born from mothers with iodine deficiency can suffer from cretinism, resulting in stunted growth and varying degrees of mental problems

12. To solve this problem, iodine has been added to both table and cooking salt • Solution was first proposed by a French chemist in the first half of the 19th century • There are risks of toxicity from excess iodine • But benefits of iodizing salt outweigh the dangers of excess iodine intake

13. Fiber • Provides bulk, helping the digestive system to function better • By eating fiber, you create a sufficient amount of volume of material for your muscles in your intestines to apply pressure to • A diet high in fiber: • Reduces likelihood of constipation • Appendicitis • Cancer • Diabetes • Cardiovascular diseases • Helps to manage body mass better • One recommendation is to five to eight servings of fruit or vegetables each day