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Components of the
Human Diet
By Josh Negrit and Alexandre Duguay
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
Vitamins and Minerals
Vitamins
Minerals
Organic
Inorganic
Contains carbon
Do not contain carbon
Synthesized in living plants and
animals
Not synthesized in living plants and
animals
Found in forms of compounds
Found in forms of ions
So why are minerals and
vitamins always grouped
together?
Because they are both needed in small quantities
Also because they both prevent deficiency diseases
How much vitamin C do we
need?
Two ways to determine this:
Animal testing
and testing on human subjects
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.
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
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
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.)
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
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
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
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