Nutrition Through the Life Cycle

Pregnancy

Nutrient	RDA Increase	Key Food Sources	Role
Folate	400 → 600 mcg DFE	Leafy greens, legumes, fortified grains	Neural tube closure (first 28 days)
Iron	18 → 27 mg	Red meat, spinach, fortified cereals	Increased blood volume, fetal iron stores
Calcium	1,000 mg (same)	Dairy, fortified plant milks, tofu	Fetal skeletal development
Vitamin D	600 IU (same)	Sunlight, fatty fish, fortified milk	Calcium absorption
Iodine	150 → 220 mcg	Iodized salt, seafood	Fetal brain development
DHA (omega-3)	200-300 mg	Fatty fish (low mercury), algal oil	Fetal brain and eye development
Protein	46 → 71 g	Meat, eggs, legumes, dairy	Tissue growth

Weight gain recommendations (IOM):

Nutrient	RDA Increase	Notes
Energy	+330 kcal/day (first 6 months)	+400 kcal/day if underweight
Protein	+25 g/day	Breast milk: 1.1 g protein/100 mL
Calcium	1,000 mg (same)	Bone mobilization if insufficient
Iodine	290 mcg	Concentrated in breast milk
DHA	200-300 mg	Crucial for infant brain development
Fluid	3.8 L/day	Breast milk is 87% water

Exclusive breastfeeding: Recommended for first 6 months Continued breastfeeding: With complementary foods up to 2 years

Age	Feeding	Key Nutrients
0-6 months	Breast milk or formula only	Iron (after 4 months), vitamin D (400 IU/day supplement)
6-8 months	Pureed foods (single ingredient), iron-fortified cereal	Iron, zinc (from meat/fortified cereals)
8-10 months	Mashed foods, finger foods	Variety of textures
10-12 months	Chopped table foods (soft)	Whole cow’s milk at 12 months

Common nutrient concerns:

Nutrient	Why	Prevention
Iron	Depleted stores by 4-6 months	Fortified cereal, pureed meat
Vitamin D	Low in breast milk	400 IU/day supplement
Vitamin B₁₂	Exclusive breastfeeding of vegan mothers	Maternal B₁₂ supplementation

Nutrient	Key Concerns
Energy	Growth requires 70-100 kcal/kg/day (varies by age)
Protein	13-34 g/day (increasing with age)
Calcium	700-1,300 mg/day (bone mass accrual)
Vitamin D	600 IU/day
Iron	7-10 mg/day (growth + menstruation in girls)
Fiber	Age + 5 g/day (up to 25 g)

Common issues: Picky eating, food neophobia, excessive added sugars, insufficient fruits/vegetables

Nutrient	Male	Female	Notes
Energy (kcal)	2,400-3,200	2,000-2,400	Growth spurt peak
Protein (g)	52	46	Growth + lean mass
Calcium (mg)	1,300	1,300	Peak bone mass accrual
Iron (mg)	11	15	Menstruation (female)
Vitamin D (IU)	600	600	Bone health

Special concerns:

Reproductive-age women: Folate (400 mcg DFE), iron (18 mg)

Concern	Change	Recommendation
↓ BMR	↓ 1-2%/decade	Adjust energy intake to prevent weight gain
↓ Lean mass	Sarcopenia (3-8%/decade)	↑ Protein to 1.2 g/kg/day
↓ Vitamin D synthesis	75% ↓ in skin synthesis	800-1,000 IU/day
↓ Calcium absorption	Age-related malabsorption	1,200 mg/day
↓ B₁₂ absorption	Atrophic gastritis (10-30%)	B₁₂ from fortified foods or supplements
↓ Thirst sensation	Dehydration risk	Encourage fluids
↓ Appetite	Early satiety	Nutrient-dense foods
↑ Constipation	Slower motility	↑ Fiber + fluids

Key nutrients at risk: Vitamin D, calcium, B₁₂, protein, fiber, potassium, fluids

Life Stage	Prioritize	Limit
Pregnancy	Folate-rich greens, iron-rich foods, fatty fish (low Hg)	Alcohol, caffeine, high-mercury fish
Infants	Iron-fortified cereal, pureed meats	Honey (< 1 year), added sugars
Children	Whole fruits, vegetables, milk, whole grains	Added sugars, highly processed snacks
Adolescents	Calcium-rich foods, iron-rich foods, protein	Sugary drinks, fast food
Adults	Fiber-rich foods, lean protein, healthy fats	Sodium, saturated fat, alcohol
Older adults	Protein-rich foods, calcium, B₁₂, vitamin D	Sodium, added sugars