1. Option A:
Human
Nutrition and
Health
A1: Components of a
human diet

2. Jamie Oliver’s TED talk
 http://www.youtube.com/watch?v=go_Q
Ozc79Uc

3. Nutrients

4. Essential vs. Non-essential
 Nutrients are chemical substances, found
in foods, that are used in the human
body.
 Essential: foods are the only possible
source of the nutrient. Ex.: some amino
acids, calcium, vitamins, water
 Non-essential: either another nutrient can
be used for the same purpose or they can
be made in the body from another
nutrient. Ex: some amino acids, glucose.

5. Types of nutrients

6. Protein deficiency malnutrition
Malnutrition Undernutrition
 A diet lacking one or A person whose
more essential diet is deficient in
nutrients. Example: Calories. Eventually
scurvy, a disease the body begins
that causes swollen
breaking down its
gums, loose teeth,
own protein
and small black and
blue spots on the skin molecules for fuel.

7. Protein deficiency malnutrition
 If there is shortage of one or more essential amino
acids in the diet, then the body cannot make
enough proteins such as plasma proteins,
extracellular proteins, DNA and plasma
membranes in the body.
 Protein deficiency malnutrition is a key factor in
kwashiorkor. Symptoms include:
 Stunted growth
 Muscle and skin problems
 Impaired mental development
 Immune system impairment
 Edema (swelling in the abdomen and legs as plasma
proteins responsible for balancing tissue fluids are not
produced, so fluid builds up)

8. Phenylketonuria
 PKU is a genetic disease caused by a
mutation of a gene coding for the
enzyme that converts phenylalanine into
tyrosine. Phenylalanine is not converted
into tyrosine.

9. Phenylketonuria
 PKUis autosomal (any chromosome that is
not a sex chromosome) and recessive (it
only occurs in individuals with two
recessive mutant alleles)
 This
disorder is progressive : its effects build
up over time and lead to ongoing
deterioration.

10. Phenylketonuria
 Sincephenylalanine is not converted it
builds up in the body causing potentially
serious consequences:
 skin disorders
 intellectual disability
 heart problems
 microcephaly can also develop in severe
cases.

11. Phenylketonuria
 PKUbabies are unaffected at birth
because their mother’s metabolism has
kept phenylalanine and tyrosine at
normal levels. This allows for early
diagnosis during the first days after birth.
http://www.nandoperettifound.org/en/pa
ge.php?project=143

12. Phenylketonuria
 Treatment:
A diet low in phenylalanine: small dosis of
meat, fish, dairy, nuts, peas and beans.
No aspartame sweeteners.
 Tyrosine supplements

13. Fatty acids

14. Molecular structure of fatty
acids
The
difference is
in the double
bonds!
All possible valences
have been
occupied

15. Molecular structure of fatty
acids
- High density energy store
- Solid at room temperature
- Animal products, palm
and coconut oil. - Usually oils at room temperature
- High risk of coronoary - Usually from plant sources
heart disease (CHD) - Olive oil
- Less risk of CHD

16. Molecular structure of fatty There is also
variation in
acids
the omega-number indicates the position of
the first double bond, from the CH3 group the structure
of
unsaturated
fatty acids.
cis- isomers
have the
hydrogen
atoms on the
same side of
the C=C
double bond,
whereas trans-
isomers have
the hydrogen
atoms on
opposite
sides. Most
trans- fats are
created
artificially.

17. Summary
 Saturated vs. Un-saturated fatty acids:
which is healthier?
 Omega 3 and Omega 6: what’s the
difference?
 Cis- vs. Trans- fatty acids: what’s the
difference? Which is healthier?

18. Evaluate the health
consequences of diets rich in the
various types of fatty acids

19. Fatty acids and health
 Many claims about the effects of different
types of fatty acids on human health. Difficult
to control experiments to show clear causal
links, instead: correlations.
 Positive correlation between saturated fatty
acid intake and rates of coronary heart
disease (CHD).
 Ex: Olive oil – contains cis-monounsaturated
fatty acids  low rates of CHD.
 However it could also be other aspects like tu
high consumption of tomatoes or genetic
factors.

20.  Positive correlation
between intake of trans
fatty acids and CHD:
Fatty deposits in arteries
of people who died
from CHD were found to
contain high
concentrations of trans
fats.
 Other risk factors do not
account for the
correlation: therefore,
trans fats probably
cause CHD

21. Omegas?
 Several long chain omega-3 fatty acids
are essential, particularly for the
development of the brain and the eye.
 There’s little or no evidence that
supplementation of a normal diet
enhances brain or eye development.

22. Vitamins and minerals

23. Minerals: Inorganic ions,
Vitamins: Organic mostly found in water, soil
compounds made by and many organic food
plant or animals. types as a result of uptake.
Vitamin C: ascorbic acid
Both are needed in the diet in relatively small quantities – mg or µg
per day. If any is lacking from the diet, a deficiency disease results.
Ex.:
mineral iodine  thyroid gland: thyroxin metabolic rate.
No iodine  iodine deficiency disorder (IDD)  goiter
development and mental impairment

24. Vitamin C
 Needed for the synthesis of the collagen fibers
that form many parts and tissues in the body
(cartilage, bones, hair, skin, blood vessel
walls).
 Linus Pauling, a distinguished chemist and
double Nobel laureate, claimed that taking
massive doses of vitamin C protects the body
against upper respiratory tract infections.
 Others have issued counter-claims: if intake is
high and later drops down to normal levels,
symptoms of scurvy develop: rebound
malnutrition.

25. How to determine the
recommended daily intake of
vitamin C
 Recommended Daily Intakes (RDI) of
vitamin C are set at 45-60mg day-1.
 These levels were determined based on a
number of experiments into levels of
vitamin C that gave optimum benefit.
 Humans and guinea pigs cannot
synthesize vitamin C, so it is possible to
measure the effects of varying vitamin C
doses in carefully controlled experiments.

26. Human trials
 Conscientious objectors from WWII volunteered to take part in a
series of medical trials in Sheffield over a four-year period.
 20 volunteers were used to measure the effects of varying vitamin
C concentrations.
 Weeks 1-6: No vitamin C in foods, but all given 70mg supplement
Weeks 7-end (8 months): 3 kept on 70mg per day, 7 were given
10mg per day and 10 were given no vitamin C at all.
 Measurement: periodic incisions were made on volunteer’s
thighs, and healing time and strength of healed tissue were
observed. Blood and urine vitamin C concentrations were
recorded.
 Outcomes: no ill effects were recorded in the 70mg or 10mg
groups. The 0mg group developed scurvy within 6-8 months and
some serious side effects were recorded, including one who
experienced heart problems, which were rectified after he was
given vitamin C.

27. Guinea pig trials
 Observe the effect of vitamin C
concentration on collagen structure
 After periods of varying vitamin C
supplementation and measurement of blood
and urine vitamin C levels, guinea pigs were
sacrificed and the structure of collagen fibers
observed.
 Guinea pigs with restricted vitamin C showed
weaker collagen.

29. Vitamin D
 Needed for calcium absorption from food in
the intestines.
 Deficiency in vitamin D is similar to deficiency
in calcium, with children developing skeletal
deformities (rickets)
 It can be synthesized in the skin with a light
source containing UV light (sunlight)
 Children, elderly and pregnant women are
recommended to eat 10µg/day.
 However, UV light has some harmful
consequences, like skin cancer. Melanin
intercepts and absorbs UV light giving good
protection against cancer, but also reducing
vitamin D synthesis.