Chapter 7

Genetically engineered to produce beta-carotene, a source of vitamin A

benefits reduce blindness and improve pregnancy

The primary effect of vitamin A deficiency is impaired vision.

Biofortification - process by which the nutritional quality of food crops is improved through land management, conventional plant breeding, or modern biotechnology.

Vitamins

Organic compounds (carbon-carbon & carbon-hydrogen bond)

Micronutrients

Essential nutrients

Individual units

Not source of energy (calories)

Fat-Soluble Vitamins

Vitamin A

Vitamin D

Vitamin E

Vitamin K

Water-Soluble Vitamins

B-complex vitamins

  • Thiamine (vitamin B1)
  • Riboflavin (vitamin B2)
  • Niacin (vitamin B3)
  • Vitamin B6 (pyridoxine)
  • Folate
  • Vitamin B12
  • Biotin
  • Pantothenic acid

Vitamin C

  • Choline (vitamin-like)

Vitamins are classified according to their solubility

  • disperse or dissolve in water or lipid
  • how absorbed and transported in body
  • where they are stored

Fat-soluble vitamins have diverse functions in the body but share common characteristics

The fat-soluble vitamins and their primary functions

Vitamin A group of fat-soluble compounds

Retinoid compounds

  • retinal
  • retinol
  • retinoic acid

Carotenoids

  • Provitamin: has vitamin activity only after conversion to the active form in the body
  • Beta-carotene
Bioavailability of vitamin A

Preformed vitamin A (retinol)

  • More readily absorbed
  • Animal foods and fortified foods

Provitamin A carotenoids

  • Yellow-, orange-, and red-pigmented fruits and vegetables

RDA given as mcg of retinol activityequivalents (RAE)

  • Conversion of beta-carotene to retinol is never complete
Vitamin A biochemical and physiological functions in the body

Vision

Functions as a hormone in:

  • Cell development
  • Immune function
  • Growth
  • Bone health
  • Reproduction

Vitamin A key for rhodopsin requires to absorb light

Beta-carotene has an important role as a phytochemical with potent antioxidant properties

High levels of free radicals can cause cellular damage (oxidation)

Hypovitaminosis A

Night blindness Permanent blindness Impaired immunity Rough, dry, or scaly skin Keratinization

Consuming too much vitamin A can result in hypervitaminosis A

Vitamin D can be produced in the skin from cholesterol and exposure to UV light

“Sunshine vitamin” Lack of sun exposure makes it essential to consume this vitamin in the diet Also consumed through the diet Must be activated in the kidneys and liver to function in the body

The RDAs for vitamin D intake through food sources are established on the basis of minimal sun exposure

Function of Vitamin D

Acts as a hormone Helps bone growth and maintenance Regulates calcium metabolism Blood levels Absorption Excretion Regulates the synthesis of certain proteins Possibly regulates cardiovascular function Ongoing research is looking into other roles in the body

Vitamin D must be activated in the kidneys and liver to fulfill its biological functions in the body

Vitamin D functions as a hormone to regulate calcium metabolism and blood concentration

Vitamin D is considered a nutrient of concern in the Dietary Guidelines for Americans

6% of Americans older than 11 may be deficient

low levels may cause bone disease

  • rickets
  • osteomalacia
  • type 2 diabetes

Vitamin E is found in a variety of foods, but the best sources are many nuts and some oils

Dietary sources: Plant-based oils Nuts and seeds Wheat germ Fortified foods

vitamin E supplementation reduces risk of heart disease or cancer

Vitamin E functions as anmantioxidant within cellular membranes

vitamin e is less likely to be toxic than a or d

UL = 1000 mg or 1500 IU 60 times the RDA

Leafy greens are the most significant dietary source of vitamin K

  • has a role in blood clotting
  • reduces risk of hemorrhage in newborns
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