Adolescent Nutrition Lecture 20

Adolescent Nutrition Lecture 20

• Adolescence is defined as the period between 11 and 21 years of age.
• Physical, social, and psychosocial development occur during this time.
• Nutritional needs are determined by biological maturity, not chronological age.
• Tanner stages (SMR) assess pubertal maturity, focusing on secondary sex characteristics, not chronological age.
• Tanner stages in females include breast development and pubic hair growth. Tanner Stages in males include genital and pubic hair growth.
• Girls experience a peak in body fat between 15 and 16 years of age.
• 17% body fat is required for menarche.
• 25% body fat is needed for a regular menstrual cycle.
• Boys gain weight that correlates with peak linear growth and muscle mass during adolescence.
• Body fat in males reduces to 12% by the end of puberty.
• A significant proportion of peak bone mass is accrued during adolescence; nearly 90% by age 18.
• Calcium intake, vitamin D, vitamin K, protein, phosphorus, magnesium, and iron are critical for adolescent bone development and minimizing osteoporosis risk later in life.
• Physical activity during adolescence plays a role in bone development.

Nutritional Challenges

• Increased needs for energy, protein, vitamins, and minerals.
• Health-compromising behaviors are common, such as skipping meals and unhealthy weight-control practices.
• Frequent consumption of foods high in fat and sugar (e.g., fast foods, soft drinks, energy-dense snacks).

Psychosocial Changes

• Early adolescence (11-14 years) is characterized by a desire to improve body image, concrete thinking, impulsive behavior, and a lack of foresight.
• Middle adolescence (15-17 years) is marked by peer influence, taking charge of food choices, and feelings of invincibility.
• Late adolescence (18-21 years) involves established body image, future-oriented thinking, and a greater interest in overall health.

Energy Requirements

• Energy needs vary based on lean mass, fat mass, skeletal mass, and activity level.
• Basal metabolic rate (BMR) and pubertal growth are key factors.
• Low energy intakes during adolescence can result in stunted growth, delayed sexual maturation, and reduced lean body mass.

Protein Requirements

• Protein is required for maintaining existing lean body mass and the growth of new lean body mass.
• The recommended daily intake (DRI) for protein is 0.85 g/kg of body weight.
• Protein needs should be assessed based on growth timing, not just chronological age.

Other Nutrients (Carbohydrates, Dietary Fiber, Calcium)

• Carbohydrates are the primary source of dietary energy, with a daily recommendation of 130 g and ranging from 45-65% of daily calories.
• Dietary fiber is important for normal bowel function and potential disease prevention. Daily recommendations vary by age and gender.
• Calcium is critical for bone mass development, with a DRI of 1300 mg/day. Calcium absorption is higher in early adolescence in both males and females. This is correlated with calorie and milk intake.

Additional Nutrients (Vitamin D, Iron, Folate)

• Vitamin D promotes calcium absorption and maintains proper serum calcium and phosphate levels.
• Iron is essential for increased blood volume and the menstrual cycle.
• Folate (400 ug/day) is important for DNA, RNA, and protein synthesis. Adequate intake can reduce the risk of birth defects like spina bifida.

Snacking, Meal Skipping, Eating Away from Home

• Snacking contributes a significant portion of calories and nutrients.
• Eating away from home often involves high-fat, high-sugar, low-nutrient foods.
• Breakfast and lunch meals are sometimes skipped.

Body Image

• Adolescents are often concerned about their body proportions and growth rate. This can lead to unhealthy dieting behaviors.
• Girls may over restrict their food intake, while boys may use supplements to build muscle.