Bone Health and Body Defense System Ch. 15 Diet


Bone is a Dynamic Organ that works with?

muscles to provide mobility for the body and help shield internal organs from injury.

What determines bone health?


Collagen and Minerals

are the primary network of protein fibers in bone.

Calcium and Phosphorus

are the main minerals in bone.

Other nutrients obtained from the diet needed for healthy bones?

Protein, Magnesium, Potassium, Sodium, Fluoride, Sulfur, Zinc, and Vitamins D and K.

2 Types of Bone

Compact (Cortical) and Spongy (Trabecular)

Cortical (Compact) Bone

Has a Dense, Outer shell that makes up 75% of skeletal mass.

Trabecular (Spongy) Bone

-Has a Hard, Spongy network of rods, plates, and spines.
-Abundant at the ends of Long Bones, Spinal Vertebrae, and inside flat bones of the Pelvis.

Bone Remodeling

Is the process of continually being built, broken down, and reshaped. Process of REMOVING and REPLACING bone.

Why is bone remodeling vital for bone health?

It allows bones to grow normally and to repair and replace damaged or brittle bones. It also permits Calcium and Phosphorus to be "withdrawn" and used for other functions when dietary intake is insufficient.

What are the 3 main types of BONE CELLS that function in growth and remodeling?

Osteoblasts, Osteocytes, and Osteoclasts

Osteoblasts are

Bone-Building cells that produce collagen, and minerals.

Osteocytes are

Bone-Building cells that take up and release bone minerals. Takes Calcium from the blood and releases back into the blood.

Osteoclasts are

Bone-Resorbing cells that release acid and enzymes to dissolve bone. Very active when Calcium is deficient in the diet; releases Calcium from the bone into the blood.

Bone-Remodeling is an ongoing process that replaces adult skeleton every

10 years

When Osteoblasts activity exceeds Osteoclasts activity

More bone is made than being broken down. Can occur when bone is put under high stress (Athletes, such as Tennis and Baseball players, build more on arms used).

More bone is built from _______ through the late ________ years. Calcium is highly recommended through these times to support bone-building activity.

infancy; adolescent

Estrogen decreases

osteoclasts activity (especially in Menopause and Amenorrhea).

Women experience greater bone loss when estrogen levels fall in menopause because

Estrogen inhibits bone breakdown by decreasing osteoclasts activity.

Amenorrhea in younger women can signal

Low estrogen levels and a likelihood in substantial bone loss before middle age.

Calcium is essential for what functions?

-Developing and maintaining bone and teeth
-Blood clotting
-Transmission of nerve impulses
-Muscle contraction
-Cell metabolism

Transmission of Nerve Impulses

Opens Calcium (Ca) channels, which triggers synaptic vesicles to release store of neurotransmitters.

Hypocalcemic tetany in Transmission of Nerve Impulses

A condition characterized by muscle spasms (Charley Horse) because the muscles receive continual nerve stimulation. Occurs when there is a lack of Calcium.

Muscle Contraction occurs when

Calcium Ions are released in muscle cells and allow contractile proteins to slide along each other.

Cell Metabolism

Activates enzymes that initiates breakdown of Glycogen.

Calcium Foods include

-Milk and Dairy
-Yeast breads, rolls, and crackers
-Kale, collard greens, turnip greens, broccoli, almonds, and calcium-fortified fruits

Milk and Dairy products provide

Bioavailable calcium. Accounts for over half of the calcium in U.S. diets.

Leafy greens have

Oxalic acid; Calcium is poorly absorbed.

The RDA of Calcium for most adults is


The RDA of Calcium for adolescents is


The RDA of Calcium for Women over 50 and Men over 70 is


People with the lowest intake of Calcium are

Females (age 9-18) and those over 71. Only 15% of younger females and 39% of older women meet RDA.

Calcium Supplements are used by older women to

Prevent bone loss and fracture

Calcium Supplements are

Generally considered safe.

Most Calcium is absorbed in the

Upper Small Intestine

Adults absorb about ____to____ of Calcium in foods, but during periods of growth (Infancy and Pregnancy), absorption levels might reach ____.

25%; 30%; 75%

Calcium absorption declines with age, especially in _________, who absorb the least.

Postmenopausal women

Skeleton and teeth hold how much Calcium?

99%; All cells have a need for Calcium.

The concentration of Calcium is regulated by

Hormonal Control; Normal blood calcium maintained even when Calcium intake is low.

Calcium may protect against

Colon Cancer

Dietary Calcium can protect against

Calcium oxalate kidney stones.

Calcium may help lower

Blood pressure

Hyperparathyroidism can cause

Persistently elevated blood Calcium.

When blood calcium levels rise too high

Less Parathyroid Hormone (PTH) is released.

Less Parathyroid Hormone (PTH) causes

-Urinary Calcium excretion to increase
-Drop in Calcium absorption
-Thyroid gland secretes calcitonin

Calcitonin blocks

Calcium loss from bone.


-A disease linked to low intakes of Calcium.
-Low dietary Calcium causes Calcium to be pulled from blood.
-Develops over many years.
-Diagnosed when bone loss and strength decline significantly

When bone loss and strength decline

Bones become fragile and likely to break. Specifically in the hip, wrist, and vertebrae in spine.

Loss of bone in spine leads to

Compression fractures, loss of height, and eventually Kyphosis (Dowager's Hump).

How many adults have Osteoporosis?

Approximately 10% aged 50+

The lowest rate of Osteoporosis are in

African Americans followed by Hispanic/Latino heritage.

The highest rate of Osteoporosis are in

Caucasians and Asians.

What type of bone scan diagnoses Osteoporosis?

Dual Energy X-Ray Absorptiometry (DEXA)

DEXA Bone Scans

-Scans the whole body
-Compares the measurements of the observed bone density to those of a person at peak bone density.

Peripheral DEXA

Only measures 1 part of the body, such as wrist or heel. This is faster than DEXA, but not as accurate because the density of a single part of the body may not reflect other areas susceptible to fractures, such as the spine.

Ways to prevent Osteoporosis

Healthy diet that provides Calcium (rich diet), Vitamin D (allows use of calcium consumed), Magnesium (improves calcium utilization), Potassium (keeps acidity in body fluids in check so it isn't removed in bones), Vitamin K, and Protein.

Rickets are caused by

A Vitamin D deficiency

Rickets can cause

Bone deformities

In 1918, scientists cured dogs with rickets by

Giving cod liver oil

Vitamin D can be synthesized by

Skin cells from sunlight

If synthesis of Vitamin D is adequate to meet needs, it can be classified as a

Conditional" vitamin or Prohormone (Precursor to an active hormone).

Functions of Vitamin D

-Maintains the body's concentration of Calcium and Phosphorus.
-Helps maintain skeletal health.
-Promotes increased intestinal absorption of calcium and phosphorus when blood calcium levels are low (can also pull from bone).
-Helps regulate immune functio

Vitamin D occurs in 2 forms

Vitamin D2 and Vitamin D3 (both have vitamin D activity in humans).

Vitamin D2 (Ergocalciferol)

Naturally in foods and is the form used in fortified foods/supplements.

Vitamin D3 (Cholecalciferol)

Synthesized in skin from sunlight.

The best food source of Vitamin D2 are

Fatty fish, cod liver oil, fortified milk, and some fortified breakfast cereals.

Milk is fortified with

10 ?g of vitamin D per quart (Cheese and Ice cream are not fortified).

Supplements use this Vitamin D form

Vitamin D2

Vitamin D3 begins with a compound called

7-dehydrocholesterol, a precursor of cholesterol synthesis located in skin.

Vitamin D3 exposure to sunlight causes

1 ring on molecule to form stable vitamin D3. This change allows vitamin D3 to enter the bloodstream for transport to the liver and kidneys where it undergoes conversion to its bioactive form (calcitriol).

Sun exposure provides ____ to ____ of vitamin D3 required by the body.

80%; 100%

The amount of sun exposure needed depends on

-Time of day
-Geographic location
-Season of the year
-One's age
-One's skin color
-Use of sunscreen

Boston, Massachusetts UV light exposure

Adequate from March to October. November to February UV light is too low to produce enough Vitamin D3.

Los Angeles has enough UV light

All year round

Production of Vitamin D3 in skin decreases by ____ by age 70.

70%; 70+ year olds do not get enough sun exposure.

Skin pigment (Melanin) in dark-skinned individuals may

Block UV light and prevent adequate D3 synthesis.

Sunscreens with SPF higher than 8

May prevent D3 synthesis

Sunlight will not cause

Toxic amount of Vitamin D3.

Vitamin D3 Needs

-Based on limited sun exposure.
-RDA for 1 to 70 year olds is 15?g/day
-RDA for adults older than 70 is 20?g/day

Breastfed infants recommended to give

10?g/day of Vitamin D

Vitamin D in the body is

-Absorbed with dietary fat from small intestine
-Stored in adipose tissue
-Excreted in body by bile that is lost in feces (small amounts lost in urine)

This deficiency disease arises in infants and children with poor Vitamin D status


Signs of Rickets are

-Enlarged head, joints, ribcage
-Deformed pelvis
-Bowed legs

In developed countries, Rickets is most commonly associated with

-Fat malabsorption
-Low milk intakes
-Minimal sun exposure (protective clothing, sunscreens, and limited outdoor activity)

Vitamin D deficiency in adults is called



-Means soft bones
-Easily fractured bones of hip, spine, and other bones
-NOT osteoporosis
-Most likely in adults with kidney or liver disease

Why are older adults in northern climates or nursing homes more at risk for Osteomalacia?

little sun exposure, low dietary intake, and impaired kidney function

Vitamin D toxicity

Can result from supplementation, especially cholecalciferol.

Almost completely eradicated the epidemic of Rickets in the 19th century

Fortification of Milk and Cod Liver Oil

Widespread inadequate Vitamin D status caused by

Low intakes of vitamin D, coupled with behaviors that limit UV exposure (time spent indoors, sunscreen, and clothing that fully covers the skin).

Functions of Phosphorus

-Major component of bones and teeth
-Critical in every cell
-Component of ATP (Energy Production)
-Phospholipids in cell membranes

Foods that provide most Phosphorus in diet.

Milk, cheese, meat, bakery products, and cereals. Additives (Monosodium phosphate, monocalcium phosphate, and iron phosphate) contribute to phosphorus in diet.

A Phosphorus deficiency

is rare, but can contribute to bone loss, decreased growth, and poor tooth development.

Phosphorus toxicity

is rare, long-term effects of high intake are unknown.

The majority of Magnesium is located in the skeleton with the role in

Calcium metabolism, magnesium contributes to bone structure and mineralization.

Research suggests that diets high in Magnesium rich foods

may help protect against Metabolic Syndrome

Magnesium has been shown to

reduce inflammation, decrease blood pressure, and prevent heart rhythm abnormalities.

Magnesium is found in

Chlorophyll- in plant based foods (Green leafy vegetables, Broccoli, Squash, Beans, Nuts, Seeds, Whole Grains, and Chocolate).

Magnesium can be found in hard tap water, which has a

High mineral content.

Coffee and Tea contain high levels of


About ____ to ____ of the Magnesium consumed is absorbed normally. When intake is low, approximately ____ is absorbed.

30%; 40%; 80%

____ of Magnesium is found in bones, the rest are stored in other tissues such as muscle.


A Magnesium deficiency causes

Irregular heartbeat, weakness, muscle spasms, disorientation, nausea, vomiting, seizures, and an increased risk for Osteoporosis.

Intakes of Magnesium exceeding the Upper level of 350mg/day from nonfood sources can lead to


Toxicity of Magnesium can also occur during kidney failure because the kidneys are a primer regulator of blood magnesium. An individual can experience

Weakness, nausea, slowed breathing, coma, and death.

Fluoride is not an essential nutrient because

All body functions can occur without it.

Fluoride reduces/prevents dental cavities in teeth by

Creating crystals that provide greater resistance to bacteria and acids in the mouth that can erode tooth enamel.

Major source of Fluoride is fluoridated water that's added to public water supply.

It is set at a safe and at an optimal level for prevention of dental cavities.

Fluoride can also be found in other sources besides fluoridated water, such as

-Tea, seafood, and seaweed
-Fluoridated toothpaste and mouth rinse

Bottled water does not contain


A lack of Fluoride is associated with an

Increased incidence of dental cavities, but does not have a disease or disorder.

Fluoride toxicity is

-Reported in young children

Symptoms of fluoride toxicity are

Nausea, vomiting, diarrhea, sweating, spasms, convulsions, and coma.

Mottling (Fluorosis) of the enamel is a result of

Chronic intake of Fluoride during tooth development, but is not associated with health risk. Causes discoloration and possible pitting of the enamel.

The body is constantly under attack by foreign invaders such as

-Bacteria and viruses
-Free radicals
-Cigarette smoke

The Immune system is

A network of cells, tissue, organs, and chemicals working together.

There are 2 basic types of Immunity

Innate (nonspecific) and Acquired (specific)

Innate (nonspecific) Immunity

-Is generally present at birth
-Includes physical barriers that block access to the body (skin) and physiological barriers (fever)
-Chemical secretions (Hydrochloric acid)

Acquired (specific) Immunity

Develops over time as the body "learns" to recognize specific molecules as foreign or "non-self" cells (antigens).

Vitamin E, Vitamin C, Selenium, Beta-Carotene (Vitamin A), Manganese, Copper, and Zinc are important parts of the

Antioxidant System

Antioxidants help maintain integrity of cells by stopping chain reactions caused by

Free Radicals

Free Radicals are

Very unstable compounds that destroy cell components like DNA and Cell Membranes.

Vitamin E is a

Fat-Soluble compound that acts as an antioxidant primarily in lipid rich areas of the body.

Vitamin E studies show that it does not

Decrease the risk of prostate and other cancers, but its effects may vary with the stage of the cancer. Inconsistent findings suggest more research is needed in regards of its effects in cancer and cardiovascular disease.

Good food sources of Vitamin E are

-Plant oils (Cottonseed, canola, safflower, sunflower oils)
-Products made with plant oils (margarine, shortening, and salad dressings)
-Wheat germ, avocado, almonds, peanuts, and sunflower seeds
-Animal fats and dairy products (contain little)

Vitamin E is destroyed by

Oxygen, metals, light, and heat (deep-fat frying)

Vitamin E is absorbed in the

Small intestine and then transported to lymph and eventually into the blood.

Vitamin E deficiency is

-People with Cystic Fibrosis, Crohn's disease, smokers, and preterm infants are at risk
-Characterized by the breakdown of red blood cells (hemolysis) and development of Hemolytic anemia
-Can impair immune function

Although vitamin E is relatively non-toxic, excessive amounts

Can interfere with the role of Vitamin K in blood clotting, which causes insufficient clotting and risk of hemorrhaging.

Vitamin C (Ascorbic Acid) is a

Water soluble vitamin that most humans and some animals can not synthesize and rely on diets as a source.

By donating electrons to free radicals, Vitamin C

Inactivates free radicals, protecting various cellular compounds (DNA, Proteins, and Lipids) form radical-induced damage.

Collagen synthesis is

-A major fibrous protein that holds various structures of the body together
-Important constituents of connective tissues (Ligaments, Tendons, Skin)

Vitamin C is needed in Collagen Synthesis to

Form the right shape of Collagen

Vitamin C aids Iron absorption by

Taking Vitamin C with meals helps absorb nonheme iron. It also counters the action of certain food components that hinder absorption.

Most Vitamin C is found in

-Citrus fruits, peppers, and green vegetables
-Orange Juice is the richest in source consumed by U.S.

Vitamin C is the least stable vitamin

Lost in storage, processing, and cooking. It can be very unstable when in contact with iron, copper, and oxygen.

Vitamin C deficiency prevents

The normal synthesis of collagen, causing widespread changes in connective tissue in the body.

Scurvy is a disease caused by 20-40 days of Vitamin C free diet that causes

-Pinpoint hemorrhages around hair follicles
-Gums and Joints bleed (Connective tissue failure)
-Impaired wound healing, bone pain, fractures, and diarrhea
-Psychological problems such as depression (common in advanced)
-Associated with poverty wo

Many (not all) studies on Vitamin C are

Inconclusive on effects for cancer and cardiovascular disease. Many show protection against heart disease and stroke, but clinical trials of supplements do not provide enough evidence.

Vitamin C is often used to prevent

The common cold at an intake of 1000mg/day. Possible reduction of 1 day of cold per year. It cannot be recommended to prevent or treat common colds for most individuals.

Selenium is

-A component of at least 25 enzymes and protein in the body
-Part of antioxidant defense network
-May decrease risk of prostate, breast, lung, or other cancers
-Food content varies depending on the soil content where plant was grown or animal was raised

A Selenium deficiency

Is not known to cause a specific disease, but can cause changes in thyroid hormone metabolism and a possible increased risk of certain cancers.

Excess supplementation of Selenium can cause

Toxicity (Selenosis); symptoms are: nausea, diarrhea, fatigue, hair loss, changes in nails, and impairment of sulfur and protein metabolism.

Vitamin A has been known for more than 3500 years as a factor the prevented

Night blindness.

Ancient Egyptians and Greek physician Hippocrates recommended consumption of

Beef liver as a cure for night blindness because it contains Vitamin A.

Vitamin A refers to

Preformed retinoids and provitamin A carotenoids.


-Are collective term for biologically active forms of Vitamin A
-Called Preformed Vitamin A because they do not need to be converted in the body to become biologically active
-Exists as retinol, retinal, and retinoic acid


-Are Yellow-orange pigmented materials in fruits and vegetables
-Some are Provitamins because they can be converted to Vitamin A such as Alpha-carotene, Beta-carotene, and Beta-cryptoxanthin

Functions of Retinoids

-Immune Function: Helps protect the body through roles in immune system and epithelium (Increased incidence of illness and infection with deficiency)
-Embryonic Development: Development of eyes, limbs, cardiovascular system, and nervous system (Lack of Vi

Functions of Carotenoids

-Can be converted to Vitamin A in the body from diet
-Diets high in source rich fruits and vegetables may decrease the risk of certain eye diseases, cancers, and cardiovascular disease
-Beta-Carotene has the most Vitamin A activity and can act as an Antio

Foods containing Vitamin A are

-Retinoids found in liver, fish, fish oils, fortified milk, and eggs
-Margarine is fortified (fat-free, low-fat, and reduced fat milk)
-Provitamin Carotenoids: Dark green and yellow-orange vegetables and fruits such as carrots, spinach, winter squash, swe

Vitamin A Deficiency

-U.S. has little risk (Abundant in our food supply), but a major issue in developing countries
-Leading cause of nonaccidental blindness (Africa, Asia, South America children at risk. 500,000 children go blind every year due to deficiency)
-Results in cha

Follicular Hyperkeratosis is caused by Vitamin A deficiency that causes

Keratin to accumulate around hair follicles (rough, dry skin).

Vitamin A Toxicity causes Hypervitaminosis A, which

Appear with long-term supplement use at 5 to 10 times the RDA for retinoids.

There are 3 types of Vitamin A toxicity

Acute, Chronic, and Teratogenic

Acute Toxicity symptoms of Vitamin A

Gastrointestinal (GI) tract upset, headache, blurred vision, poor muscle coordination

Chronic Toxicity symptoms of Vitamin A

Joint pain, skin disorders, loss of appetite, liver damage, headache, hemorrhage, and coma

Teratogenic Toxicity symptoms of Vitamin A

Most serious and tragic. Causes birth defects.