Transcript Chapter 9: Vitamins: Vital Keys to Health

Understanding Vitamins
• Vitamins
– Needed in small amounts (ug or mg)
– Not an energy source
– Vita(life)amine(containing N), are organic
molecules needed as cofactors for enzymes
– Essential for normal functioning, growth, and
maintenance
Understanding Vitamins
• Fat-soluble vs. water-soluble
– Fat-soluble: vitamins A, D, E, K
• Absorbed with fat, into lymphatic system
• Stored in larger quantities
• Less vulnerable to cooking losses
– Water-soluble: 8 B vitamins and vitamin C
• Absorbed into bloodstream
• Stored in small amounts
• Vulnerable to cooking losses
Understanding Vitamins
• Food preparation affects vit content in food
• Factors that determine amounts
–Source (animal vs. plant)
–Sunlight
–Moisture
–Growing conditions
–Plant’s maturity at harvest
–Packaging and storage
Bioavailability – quantity & absorption
Efficiency of dig. & transit time
nutrient status
other foods eaten
food preparation
source of nutrients
Organic – can be destroyed by:
- Temp
- UV
- Oxygen
- Water
Understanding Vitamins
• Vitamins in foods
– Enrichment and fortification
• Enriched—replacing lost ingredients
• Fortified—adding extra nutrients to foods
• Some is required by law
– Provitamins
• Inactive
Would your body have requirements that
are greater than what you can receive in a
balanced diet?
Who thinks RDA is too low?
Is benevolent industry CEOs thinking of
your best interest?
So is more better?
Argument against supplements
Toxicity
Reduce bioavailability of other nutrients
False sense of security
Interfere with action of some medications
Who may need supplements?
People with nutritional deficiencies
Low food intake diets
Vegans
Women of child bearing age
Infants
Certain medications
People with certain diseases, infections or injuries
People with genetic disorders
Vitamin A: The Retinoids
• Food sources
– Preformed vitamin A: liver, milk, egg yolks
– Beta-carotene: yellow/orange fruits and
vegetables
Vitamin A
• Forms of vitamin A
– Active forms (retinoids)
• Retinol
• Retinal
• Retinoic acid
– Carotenoids
Vitamin A
• Functions of
vitamin A
– Vision: night
and day
• Night and
color vision
• Becomes
part of the
retina
Vitamin A
• Functions of vitamin A
– Cell production and differentiation
– Skin
– Immune function
– Reproduction
– Bones
• Dietary recommendations
– Retinol activity equivalent (RAE)
Vitamin A
• Vitamin A deficiency
– The eyes
• Xerophthalmia
– The skin and other epithelial cells
• Keratin
– Immune function
• Vulnerable to infection
– Other effects
• Growth retardation, bone deformities,
defective teeth, and kidney stones
Vitamin A Toxicity
• Symptoms: loss of appetite, skin disorders,
blurred or double vision, and liver damage
• Teratogen
– Causes birth defects
– Discoloration of skin
• Acne treatment
– Retin-A and Accutane—use with caution
The Carotenoids-Plant pigments
• Convert vitamin A
• Functions
– Antioxident
– Lower risk of certain
cancer
– Orange and yellow fruit
and vegetables, dark
green vegetables
– Dietary fat increases
absorption
Photo © PhotoDisc
Vitamin C, also known as ascorbic
acid, is a water-soluble vitamin.
Unlike most mammals and other
animals, humans do not have the
ability to make their own vitamin C.
Therefore, we must obtain vitamin C
through our diet.
Vit C is required for synthesis of
collagen, an important structural
component of blood vessels, tendons,
ligaments, and bone.
- a highly effective antioxidant.
- regenerate other antioxidants such
as vit E
Antioxidants block some of the damage
caused by free radicals.
They are made when you breaks down
food or when exposed to tobacco smoke
or radiation.
The buildup of free radicals over time is
maybe responsible for aging.
Free radicals may play a role in cancer,
heart disease, and conditions like
arthritis
A number of possible problems with
very large doses of vitamin C have
been suggested, including:
atherosclerosis, kidney stones,
excess iron absorption,
vitamin B12 deficiency,
erosion of dental enamel
Table 1: Recommended Dietary Allowances (RDAs) for Vitamin C
Age
Male
Female
Pregnancy
Lactation
0–6 months
40 mg*
40 mg*
7–12 months
50 mg*
50 mg*
1–3 years
15 mg
15 mg
4–8 years
25 mg
25 mg
9–13 years
45 mg
45 mg
14–18 years
75 mg
65 mg
80 mg
115 mg
19+ years
90 mg
75 mg
85 mg
120 mg
Smokers
Individuals who smoke require 35 mg/day
more vitamin C than nonsmokers.
Selected Food Sources of Vitamin C [12]
Milligrams (mg) per serving
Percent (%) DV*
Red pepper, sweet, raw, ½ cup
95
158
Orange juice, ¾ cup
Orange, 1 medium
Grapefruit juice, ¾ cup
Kiwifruit, 1 medium
93
70
70
64
155
117
117
107
Green pepper, sweet, raw, ½ cup
60
100
Food
51
85
Strawberries, fresh, sliced, ½ cup
49
82
Brussels sprouts, cooked, ½ cup
48
80
Grapefruit, ½ medium
Broccoli, raw, ½ cup
Tomato juice, ¾ cup
Cantaloupe, ½ cup
39
39
33
29
65
65
55
48
Cabbage, cooked, ½ cup
28
47
Cauliflower, raw, ½ cup
26
43
Potato, baked, 1 medium
17
28
Tomato, raw, 1 medium
17
28
Spinach, cooked, ½ cup
9
15
Green peas, frozen, cooked, ½ cup
8
13
Broccoli, cooked, ½ cup