Nutrition Basics: An Active Approach - Key Vocabulary

Nutrition Basics: Nutrients Important for Bone Health

Chapter Overview

• Understanding the importance of nutrients for bone health and the biological processes involved in bone maintenance.

1. Bone Structure and Function

• Bone Remodeling Process: Explains how bones are living tissues that undergo continuous remodeling.
• Osteoblasts: Cells that build new bone.
• Osteoclasts: Cells that break down bone tissue.
• Osteocytes: Mature bone cells that maintain bone matrix.
• Importance of the Skeletal System:
• Facilitates movement.
• Provides support and protection to organs.
• Plays a role in blood cell synthesis and mineral storage.
• Composition of the Skeleton:
• Total of 206 bones, divided into:
  • Axial Skeleton: 80 bones (skull, vertebral column, rib cage).
  • Appendicular Skeleton: 126 bones (limbs, shoulder and pelvic girdles).

2. Bone Anatomy and Microarchitecture

• Bone Tissue Types:
• Cortical Bone (Compact Bone): Dense outer layer, provides strength.
• Trabecular Bone (Spongy Bone): Lighter, has a honeycomb structure, houses bone marrow.
• Bone Composition:
• 65% inorganic material (mineralized matrix, primarily hydroxyapatite).
• Organic materials from cells and collagen fibers.

3. Nutrients Essential for Bone Health

3.1. Calcium

• Functions:
• Bone and tooth formation.
• Muscle contraction and nerve transmission.
• Blood clotting and hormone secretion.
• Hormonal Regulation:
• Parathyroid Hormone (PTH): Increases calcium levels in blood.
• Calcitriol (active Vitamin D): Enhances calcium absorption in the intestines.
• Calcitonin: Lowers calcium levels in blood when necessary.
• Dietary Sources:
• Dairy products, fortified foods, green vegetables (broccoli, kale).
• Reference Intakes: Daily recommended values vary by age and conditions (Table 9.1 provides specific values).

3.2. Vitamin D

• Synthesis:
• Derived from cholesterol, activated by sunlight exposure.
• Risks of deficiency lead to rickets in children and osteomalacia in adults.
• Health Benefits: Linked to decreased risk of various diseases, including certain cancers and autoimmune disorders.
• Sources:
• Fatty fish, fortified dairy products, sunlight exposure.
• Reference Intakes: Recommendations vary (Table 9.3 shows values by age group).

4. Other Essential Micronutrients for Bone Health

4.1. Phosphorus

• Essential for bone formation; mostly found in bones.
• Function: Works with calcium to form bone tissue.
• Sources: Found in meat, dairy, nuts.

4.2. Magnesium

• Important for ATP metabolism and enzymatic reactions.
• Sources: Green leafy vegetables, nuts, whole grains.

4.3. Fluoride

• Helps prevent tooth decay and supports bone mineralization.
• Sources: Fluoridated water, toothpaste.

4.4. Vitamin K

• Aids in modifying proteins for bone health; important for blood clotting.
• Sources: Leafy green vegetables, liver, fermented foods.

5. Osteoporosis

• Definition: A condition characterized by excessive bone loss, leading to increased fracture risk.
• Types:
• Type 1: Common post-menopausal osteoporosis.
• Type 2: Common in older individuals, particularly after 70.
• Bone Density Measurement: Dual-energy X-ray absorptiometry (DEXA) for assessing risk and diagnosing osteoporosis.

6. Risk Factors for Osteoporosis

6.1. Nonmodifiable Risk Factors

• Gender, age, ethnicity (Caucasian and Asian), family history, hormonal levels, certain diseases.

6.2. Modifiable Risk Factors

• Physical inactivity, smoking, excessive alcohol, poor diet (low calcium, vitamin D).

7. Prevention and Treatment of Osteoporosis

7.1. Primary Prevention

• Focus on building peak bone mass through adequate nutrition (calcium, vitamins A, C, D, E, K) and physical activity during youth.

7.2. Secondary Prevention

• Screen for underlying diseases, implement lifestyle changes, and utilize pharmacotherapy when necessary.

8. Deficiency and Supplementation

• Groups at risk for calcium inadequacy: adolescents, postmenopausal women, lactose intolerant individuals, vegans.
• Supplements: Calcium carbonate and calcium citrate are common forms; must be taken with vitamin D for optimal absorption.
• Debate on supplementation emphasizes the importance of sufficient dietary intake first, as excessive calcium may cause health issues.

Key Takeaways for Study

• Ensure understanding of bone anatomy, nutrient functions, and the complex interplay of risk factors regarding osteoporosis.
• Master the nutritional requirements, food sources, and the effects of deficiencies on bone health.
• Be familiar with prevention strategies to maintain bone health through diet and lifestyle choices.