Transcript IB Biology Option A

Human Nutrition and Health
Part One: A.1.1 through A.1.14
VOCABULARY LIST FOR A1.1. THROUGH A.1.14
Nutrient
Balanced diet
Lipid
Protein
Carbohydrate
Fatty acid
Mineral
Vitamin
Amino acid
Water
Malnutrition
Phenylalanine hydroxylase
Essential fatty acid
Vitamin A
Vitamin B
Vitamin C
Vitamin D
Iodine Deficiency disorder
A.1.1. Define nutrient: A chemical
substance found in foods that is used in
the human body. There are five main
types of nutrients: carbohydrate,
protein, lipid, minerals, and vitamins.
A.1.2 What nutrients
are essential in the
human diet?
Essential nutrients are those
that cannot be synthesized
by the body: amino acids,
fatty acids, minerals,
vitamins, and water.
Carbohydrates are not
included because in certain
human diets, the energy is
obtained from other sources
without ill effect.
A.1.3. State that non-essential amino acids can be
synthesized in the body from other nutrients.7
Many foods contain protein, such as beef, salmon,
seeds, nuts, and soybean products. Proteins food
are digested into amino acids, which are absorbed
and used in protein synthesis. Protein synthesis
allows growth, regeneration of hair, nails, blood,
and skin, and the repair of damaged tissues.
A.1.4. Outline the consequences of protein deficiency malnutrition.
Protein deficiency is the result of a shortage of essential amino acids:
it can cause a lack of BLOOD PLASMA PROTEINS and thus TISSUE
FLUID RETENTION, and SWELLING OF THE ABDOMEN.
Children who suffer from portein deficiency are more likely to be
mentally and physically retarded.
The most reliable sources
of essential amino acids are
meant, eggs, cheese, and
other animal products.
Protein deficiency seems most common in foreign
countries in Africa and Latin America. Malnutrition
can be caused by economic, environmental, social, and
cultural factors.
A.1.5 Explain the causes and consequences of phenylketonuria (PKU) and how early
diagnoses and a special diet can reduce the consequences.
Phenlyketonuria, or PKU, is an
autosomal recessive genetic
disorder in which the enzyme
phenylalanine hydroxylase
(PAH) is deficient and cannot
metabolize the amino acid
phenylalanine to the amino acid
tyrosene. When this occurs,
phenylalanine accumulates and
instead of being metabolized into
tyrosene, is converted into
phenylpyruvate. With no
treatment, it can cause problems
with brain development and lead
to mental retardations and cause
seizures. There is no known cure,
and the damage is irreversible.
Early diagnoses is crucial.
PKU is one of few genetic diseases that can be
controlled by diet: one who has PKU must eat a
diet low in phenylaline (staying away from
foods like meat, chicken, fish, and nuts) and
high in tyrosene.
A.1.6 Outline the variation in the molecular structure of fatty acids, including
saturated fatty acids, cis and trans unsaturated fatty acids, monounsaturated and
polyunsaturated fatty acids.
Example of a saturated fat:
saturated carbon atoms.
Example of a trans-unsaturated fatty
acid. Unsaturated carbon atoms.
Example of a cis-unsaturated fatty
acid: unsaturated carbon atoms.
Essential fatty acids, or EFAs, are fatty acids that cannot be constructed within an organism from other
components (generally all references are to humans) by any known chemical pathways; and therefore
must be obtained from the diet. The term refers to those involved in biological processes, and not fatty
acids which may just play a role as fuel. As many of the compounds created from essential fatty acids can
be taken directly in the diet, it is possible that the amounts required in the diet (if any) are overestimated. It
is also possible they can be underestimated as organisms can still survive in unideal, malnourished
conditions.
In biochemistry and nutrition, monounsaturated fats are fatty acids that have a single double
bond in the fatty acid chain and all the carbon atoms in the chain are single-bonded. By contrast,
polyunsaturated fatty acids have more than one double bond.
In nutrition, polyunsaturated fat is an abbreviation of polyunsaturated fatty acid. That is a fatty acid in
which more than one double bond exists within the representative molecule. That is, the molecule has
two or more points on its structure capable of supporting hydrogen atoms not currently part of the
structure. Polyunsaturated fatty acids can assume a cis or trans conformation depending on the
geometry of the double bond.
A.1.7 Evaluate the health consequences of diets rich in the different types of fatty acid.
Many animal products are
considered “complete,” meaning
they have all the essential
amino acids in their right
proportions. “Incomplete” foods
are deficient in one or more
essential amino acids. Corn, for
example, is deficient in the
amino acid lysine. People forced
by economic necessity or other
circumstances to obtain nearly
all of their calories from corn
would show symptoms of
protein deficiency, as would
those who eat only rice, wheat,
or potatoes. The problem can be
avoided by eating a
combination of plant foods that
can complement one another to
supply all essential amino acids
(Campbell 853).
For example, beans supply the
lysine that is missing in corn: and
while beans are deficient in
methionine, this essential amino
acid is present in corn.
A.1.8 Distinguish between mineral and vitamins in terms of their chemical nature.
A mineral is a chemical element. At least 20 different minerals are essential to the
human body, such as zinc, or iodine, and must be ingested in sufficient quantities to
prevent a deficiency disease.
A vitamin is an organic compound. They are needed in the body in small quantities,
but cannot be synthesized in the body . Examples include Retinol, Ascorbic Acid, and
Tocopherol.
A.1.9 Outline 2 of the methods that have been used to determine the
recommended daily intake of Vitamin C.
This includes in vitro research and retrospective research ( looking back at
diseases and events)
In vitro research adds vitamin C to various cellular components and looks at the
results. Retrospective research looks at the diseases caused, and the levels of
vitamin C in those suffering them.They also looked extensively at the diet of
Inuits, who do not each much plant matter at all, yet do not get scurvy.
A.1.10 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.
This is Vitamin C.
This is a more important vitamin C: 
RDA is 65-90 mg a day ( less for women)
Maximum dosage RDA is 2,000mg/day
Linus Pauling took 6,000-18,000 mg /day.
Some current scientists recommend up to 3,000
mg/day
Scurvy is prevented with 40 mg/day
Vitamin C, or ascorbic acid, is an essential nutrient to mammalian bodies. Vitamin C
is used as an antioxidant, acting to lessen oxidative stress. It acts as an “electron door”
for eight different enzymes, it is a substrate for ascorbic peroxidase, and an enzyme
cofactor for the biosynthesis of many important biochemicals.
Vitamin C helps prevent scurvy, which occurs when the lack of the
vitamin prevents collagen from functioning. Scurvy leads to liver spots
on the skin, spongy gums, and bleeding from mucous membranes.
To prevent scurvy and other potential sicknesses (it can be argued that a higher
intake can prevent respiratory infections, and also rebound malnutrition), there is
a recommended daily intake of vitamin C.
Vitamin C is used in collagen synthesis, and it aids in detoxification. It also improves iron
absorption, and as mentioned before, is an antioxidant.
The recommended daily intake of Vitamin C is almost as debated as Obama versus Hilary,
but the World Health Organization recommends 45 milligrams per day to prevent sickness.
However, too large of doses can cause indigestion and diarrhea.
Rebound malnutrition occurs when a normally adequate intake of a vitamin follows
a period of excessive intake and excretion.
Foods with Vitamin C:
fruits and vegetables
(esp. citrus fruits,
broccoli, cabbage,
tomatoes, and green
peppers.
A.1.11 List the sources of vitamin D in human diets.
Sources of Vitamin D: Vitamin D can be found in dairy products and egg yolks,
but is also made in the human skin in the presence of sunlight. Vitamin D is
needed for calcium absorption in the intestines. It helps keep calcium levels in the
blood within narrow limits and ensures that sufficient calcium is supplied to muscles
and bones.
A.1.12 The risk of Vitamin D deficiency from insufficient exposure to sunlight
balanced against the risk of contracting malignant melanoma.
Vitamin D regulates the calcium and phosphorus levels in the blood by promoting their absorption from food in the
intestines, and by promoting re-absorption of calcium in the kidneys.
It promotes bone formation and mineralization and is essential in the development of an intact and strong skeleton.
It inhibits parathyroid hormone secretion from the parathyroid gland.
Vitamin D affects the immune system by promoting phagocytosis, anti-tumor activity, and immunomodulatory
functions.
As mentioned previously, the presence of sunlight allows the human skin to produce Vitamin D in large quantities.
However, the ties between an overproduction in Vitamin D and the contraction of malignant melanomas are greatly
disputed: The use of sunscreen and sun protection factors can inhibit the production of Vitamin D up to 90%.
Studies have shown that those who do use protection against the sun regularly are more likely to become Vitamin D
deficient. However, and somewhat ironically, many other studies suggest that Vitamin D deficient individuals are
more likely to contract certain types of skin cancer: An estimate of premature cancer mortality in the U.S. due to
inadequate doses of solar ultraviolet-B radiation.
A.1.13 Explain the benefits of artificial dietary supplementation as a means of preventing
malnutrition, using iodine as an example.
Artificial dietary supplementation is the addition of a dietary supplement into the
diet of an individual to prevent a deficiency of that particular nutrient and thus
malnutrition.
An example would be the frequency of
iodine deficiency disorder (IDD),
which causes swelling of the thyroid in
the neck. This is called goiter, which is
most common in the Central African
Republic and Syria but can be found in
all parts of the world.
Goiter is very serious: if women are
affected during pregnancy, their
children are born with permanent
brain damage. If children suffer from
IDD after birth, their mental
development and intelligence are
impaired.
In 1990, a campaign was started to
eliminate IDD by adding it in small
quantities to salt sold for human
consumption. By adding iodine to
salt and providing that salt to
populations suffering from IDD,
the number of those suffering
diminished significantly. In 2000,
iodized salt was reaching more
than 3.3 billion people throughout
the world.
A.1.14 Outline the importance of fiber as a component of a balanced diet.
Many populations in undeveloped countries suffer from malnutrition and the
deficiency of nutrients. However, even in industrialized countries, individuals can
suffer from deficiencies.
Fiber cannot be digested in the small intestine. Cellulose from plant cell walls is
the main component of dietary fiber, but there are other components including
chitin, and lignin. Soluble fiber ferments in the large intestine, which provides
necessary short chain fatty acids from the bacteria.
Fiber has been shown to help prevent constipation by increasing the
bulk of material in the large intestine.
Fiber may reduce the risk of diseases of the large intestine including
appendicitis, cancer, and hemorrhoids. It can also prevent obesity by increasing
the bulk in the stomach, which reduces the desire to eat more food. Fiber can
increase the rate of absorption of calcium.