1. Jamie Pope, Steven Nizielski, and Alison McCook
NUTRITION
for a Changing World
FIRST EDITION
Chapter 10
Fat-Soluble Vitamins
Soak Up the Sun?
© 2016 by W. H. Freeman and Company & Scientific American

2. Chapter 10
Objectives
Identify the fat-soluble vitamins and their primary functions
Describe the properties of the fat-soluble vitamins
Describe the role of vitamin D in blood calcium regulation
Identify excellent dietary sources of the fat-soluble vitamins
Describe the role of vitamin A in healthy vision
List sources of free radicals and describe how antioxidants can block oxidative damage
Explain how vitamin E works as an antioxidant in the cell membrane

3. Kimani the Gorilla Dying from vitamin D deficiency Has rickets
Bone malformation and muscle weakness
Treated with tenfold the normal dose of vitamin D supplementation
In 2005 Michael Holick, PhD, MD, (an endocrinologist) was called to see a 7-month-old gorilla born in captivity at Franklin Park Zoo. The gorilla exhibited signs of rickets, but a normal dose of vitamin D didn’t make much difference. Dr. Holick recommended tenfold the normal dose, and she responded. She will likely never be as tall as other gorillas, but she improved.

4. Vitamins Organic compounds Micronutrients Essential nutrients
Individual units

5. Vitamins Bioavailability Solubility
Determinant of absorption and transportation process
Affects where they are stored and risk for toxicity
Fat-soluble
Vitamins A, D, E, and K
Water-soluble
B vitamins, choline, and vitamin C

6. Properties of Fat-Soluble Vitamins

7. Vitamin D “Sunshine vitamin”
Made in skin
From cholesterol and UV light
Not enough sun exposure makes it essential to consume in diet
Activated in the kidneys and liver

8. Sources of Vitamin D

9. Functions of Vitamin D Acts as a hormone
Helps bone growth and maintenance
Regulates calcium
Regulates protein synthesis
Possibly regulates cardiovascular function

10. Vitamin D Activation
Calcitriol: fully activated form from the kidney

11. Regulation of Blood Calcium
Calcitriol increases absorption of calcium in the intestine
Active vitamin D and parathyroid hormone decrease calcium excretion by the kidneys

12. Vitamin D Deficiency Evidence that deficiency may increase risk of
Rickets (in children)
Osteomalacia (in adults)
Cancer
Autoimmune disease
Kidney disease
Type 2 diabetes
Cardiovascular disease

13. Vitamin A Retinoids Carotenoids Preformed as already in active form
Retinal
Retinol
Retinoic acid
Carotenoids
Provitamin, not in active form
Beta-carotene
Retinol is the only retinoid present in our diet. It is readily converted to retinal or retinoic acid in the body. These are the active forms of vitamin A. Carotenoids are provitamins, as they must be converted in the body into one of the active forms of the vitamin. The primary carotenoid is beta-carotene.

14. Sources of Vitamin A Preformed Provitamin A carotenoids
Animal foods and fortified foods
In the United States and Canada: reduced- and low-fat milk and yogurt must be fortified due to loss during the removal of fat
Provitamin A carotenoids
Yellow-, orange-, and red-pigmented fruits and vegetables
RDA given as mcg of retinol activity equivalents (RAE)
Conversion of beta-carotene to retinol is never complete
Absorption of carotenoids from food is poor
Slicing, chopping, cooking, juicing, and cooking can improve bioavailability

15. Dietary Sources of Vitamin A

16. Functions of Vitamin A Vision Cell development Immune function Growth
Bone health
Reproduction
In all functions except vision, vitamin A acts as a hormone by controlling the synthesis of numerous proteins encoded in our genes.

17. Vitamin A in Vision
Key component of rhodopsin

18. Oxidation
Source of free radicals and their effects

19. Antioxidants Plant forms of vitamin A Carotenoids and beta-carotene
Eating foods rich in carotenoids is associated with less risk for cancer, but research suggests that supplements may actually increase cancer risk.

20. Vitamin A Deficiency Hypovitaminosis A Night blindness
Permanent blindness
Impaired immunity
Rough, dry, or scaly skin
Keratinization

21. Vitamin A Toxicity Hypervitaminosis A UL for adults is 3,000 mcg RAE
Can cause osteoporosis
Comes mostly from supplements
UL for adults is 3,000 mcg RAE
Pregnant women need to be cautious
Can cause birth defects
Animal foods and supplements
Excess of plant sources does not cause toxicity
Beta-carotene can turn your skin yellow

22. Vitamin E Tocopherols RDA for 19 years and older is 15 mg or 22.4 IU
Dietary sources

23. Functions of Vitamin E
Antioxidant

24. Vitamin E Toxicity UL = 1,000 mg or 1,500 IU
Caused by high supplement intake
Increases tendency to bleed

25. Vitamin K Produced by bacteria in the intestine Dietary sources
The requirements are given in Adequate Intake (AI) amounts since current knowledge does not provide sufficient evidence to establish a specific RDA.

26. Functions of Vitamin K Blood clotting Bone metabolism
Needed for synthesis of protein for blood clotting
Bone metabolism
Modifies bone proteins

27. Vitamin K Deficiency Hemorrhaging
Antibiotic use can kill intestinal bacteria and decrease this source of vitamin K. Anticoagulants interfere with the metabolism of vitamin K to help prevent blood clotting. Those on these medications must strive to keep vitamin K intake consistent, as the vitamin can interfere with the medication. Since the early 1960s, infants receive vitamin K at birth to reduce the risk of hemorrhage because they have limited stores and lack bacteria to produce vitamin K.

28. Summary
Vitamins are organic compounds (containing both carbon–carbon and carbon–hydrogen bonds) that are needed in small quantities for very specific functions, such as the maintenance of regulatory and metabolic processes in the body
Most vitamins are in their active form (preformed) in foods; however, in some cases, inactive, precursor forms of vitamins, called provitamins, must be converted to fulfill biological functions in the body
Inadequate or excessive intake of vitamins can lead to deficiency or toxicity, with adverse health effects
The 14 known vitamins are classified by their solubility, as fat-soluble or water-soluble
The fat-soluble vitamins (A, D, E, and K) have diverse functions in the body

29. Summary (Cont’d)
Fat-soluble vitamins are transported in the body via the lymph, and excess intake is stored in fatty tissues and the liver, from which the vitamins are released when needed
The body derives vitamin A from preformed A (retinol) found in animal foods and fortified foods, and to a lesser degree from provitamin A carotenoids in plant foods, as conversion to the active form is incomplete
Vitamin A serves many critical biochemical and physiological functions in the body related to vision, cell development, reproduction, immune function, and growth, among others; the carotenoids have antioxidant properties in the body, which help protect cells from damage caused by free radicals

30. Summary (Cont’d)
Vitamin D, which functions as a hormone in the body, is actually not considered an essential nutrient in the diet unless there is inadequate sun exposure because it can be synthesized from cholesterol through exposure of the skin to UV light; among other important functions, vitamin D plays a key role in the growth and maintenance of bone, in part through its role in maintaining calcium concentrations in the blood
Serving primarily as an antioxidant in the body, vitamin E is a group of compounds called tocopherols, found primarily in nuts and vegetable oils
Vitamin K is an essential nutrient found in foods such as leafy greens; a significant amount of our daily requirements may also be produced by bacteria in the intestine
Vitamin K plays a key role in blood clotting and bone metabolism