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 nutrientsOrganic – 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

ToxicityReduce bioavailability of other nutrientsFalse sense of securityInterfere with action of some medications

Who may need supplements?People with nutritional deficienciesLow food intake dietsVegansWomen of child bearing ageInfantsCertain medicationsPeople with certain diseases, infections or injuriesPeople 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

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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

SmokersIndividuals who smoke require 35 mg/daymore 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 93 155

Orange, 1 medium 70 117

Grapefruit juice, ¾ cup 70 117

Kiwifruit, 1 medium 64 107

Green pepper, sweet, raw, ½ cup 60 100

Broccoli, cooked, ½ cupFood

5185

Strawberries, fresh, sliced, ½ cup 49 82

Brussels sprouts, cooked, ½ cup 48 80

Grapefruit, ½ medium 39 65

Broccoli, raw, ½ cup 39 65

Tomato juice, ¾ cup 33 55

Cantaloupe, ½ cup 29 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