Prudent Diet - K. Park

Definition / Context

Dietary Goals ("Prudent Diet") - WHO Recommendations

Note: These recommendations do not apply under special conditions such as growth, pregnancy, lactation, physical activity, or medical disorders (e.g., diabetes), where the diet must be adapted accordingly.

Prudent Diet in the Context of CHD Prevention

• Reduction of fat intake to 20-30% of total energy intake
• Saturated fats limited to less than 10% of total energy intake; some reduction may be made up by mono- and poly-unsaturated fats
• Reduction of dietary cholesterol to below 100 mg per 1000 kcal/day
• Increase in complex carbohydrate consumption (vegetables, fruits, whole grains, legumes)
• Avoidance of alcohol consumption; reduction of salt intake to 5 g daily or less

Prudent Diet for Hypertension Prevention

• Reduced salt intake
• Avoidance of high alcohol intake
• Regular physical activity
• Weight control

Key Points for Exam

1. The "prudent diet" is the dietary goal framework recommended by WHO Expert Committees and cited throughout Park's under nutrition, CHD prevention, and hypertension.
2. Fat: 15-30% total; Saturated fat: <10%; Protein: 10-15%
3. Salt: ≤5 g/day (India currently averages 15 g/day)
4. Emphasizes complex carbohydrates, fibre, unsaturated fats
5. Restricts refined carbohydrates, saturated fats, alcohol, junk foods (empty calories)
6. It forms the backbone of population strategy for primordial and primary prevention of CHD and hypertension.

• Park's Textbook of Preventive and Social Medicine, Dietary Goals section, p. 734
• Park's Textbook of Preventive and Social Medicine, CHD Specific Interventions - Population Strategy

Prudent Diet (K. Park / WHO)

Dietary Goals - 7 Points

Prudent Diet in CHD Prevention (Population Strategy)

• Total fat: 20-30% of energy
• Saturated fat: <10% of energy (replace with mono/poly-unsaturated fats)
• Dietary cholesterol: <100 mg per 1000 kcal/day
• Increase complex carbohydrates (vegetables, fruits, whole grains, legumes)
• Avoid alcohol; salt ≤5 g/day

Prudent Diet in Hypertension (Multifactorial Approach)

• Reduced salt + avoid excess alcohol + physical activity + weight control
• Even 2-3 mm Hg reduction in mean BP in the population = significant reduction in cardiovascular events

Exam High-Yield Points

• The prudent diet is the cornerstone of primordial and primary prevention of CHD
• It forms the population strategy in CHD prevention
• Special conditions (pregnancy, lactation, growth, diabetes) require diet modification beyond these goals
• Salt in India = ~15 g/day vs. goal of ≤5 g/day - a major gap

Demographic Gap

Definition

The difference between the Birth Rate (BR) and the Death Rate (DR) of a population at any given time.

Demographic Transition Theory (Background)

The demographic gap is widest in Stage II - this is the "population explosion" phase. Most developing countries, including India, have been passing through Stage II-III.

Importance of Demographic Gap in Population Dynamics

1. Population Explosion

• A wide demographic gap = rapid natural increase in population
• India's population grew from 361 million (1951) to over 1.4 billion today largely due to this gap
• Death rates fell sharply after independence (due to control of epidemics, improved nutrition) but birth rates remained high

2. Indicator of Health Development

• A falling death rate (narrowing the gap from the DR side) reflects improvements in:
  • Public health infrastructure
  • Medical care and immunization
  • Sanitation and safe water
  • Nutrition status

3. Age Structure and Dependency Ratio

• A wide gap produces a young population pyramid (broad base)
• High proportion of children = high dependency ratio
• Economic burden on the working-age population increases

4. Resource Strain

• Rapid population growth (from a wide gap) strains:
  • Food supply, housing, education, employment
  • Healthcare systems
  • Environmental resources

5. Planning and Policy

• The gap helps planners estimate future population size
• A widening gap signals the need for family planning programmes
• India's National Family Welfare Programme was designed specifically to narrow the demographic gap by reducing birth rates

6. Natural Rate of Increase

• Demographic gap directly gives the natural rate of increase (NRI)
• NRI = (BR - DR) / 10 = percentage annual population growth
• Example: BR = 20/1000, DR = 7/1000 → Gap = 13 → NRI = 1.3% per year

7. Epidemiological Transition Link

• As the demographic gap narrows and population ages, the disease pattern shifts from communicable diseases to non-communicable diseases (double burden of disease)

India's Demographic Gap (Key Data - K. Park)

• India's gap has been narrowing in recent decades as birth rates have fallen
• The goal is to achieve Net Reproduction Rate (NRR) = 1 (replacement level fertility)

Summary - Exam Points

1. Demographic gap = Birth Rate - Death Rate
2. Widest gap = Stage II of demographic transition = population explosion
3. Important for estimating natural rate of increase
4. Wide gap → young population, high dependency ratio, resource strain
5. India's family planning programme aims to narrow the demographic gap
6. Narrowing gap → ageing population → shift to NCDs (epidemiological transition)

Sex Ratio - Definition, Types & Factors Affecting It in India

Definition of Sex Ratio (K. Park)

Sex ratio is defined as "the number of females per 1000 males."

Primary Sex Ratio

The sex ratio at the time of fertilization (conception).

• Since X and Y sperms are formed in equal numbers, the primary sex ratio is expected to be 1:1 (100 males : 100 females), i.e., ratio = 1.00
• This is the theoretical ratio at the moment of fertilization
• It is difficult to measure directly

Secondary Sex Ratio

The sex ratio at birth (i.e., among live-born neonates).

• In reality, more males are born than females in all countries
• In Western countries (e.g., North America): secondary sex ratio ≈ 1.05 (105 males per 100 females)
• In India: sex ratio at birth (2016-18) = 899 females per 1000 males
• This deviation from the primary ratio is due to higher male embryo mortality in utero, and in India, is further distorted by female foeticide and sex-selective abortion

Tertiary (Adult/Census) Sex Ratio

The sex ratio in the general living population (as recorded at census).

• India Census 2011: 943 females per 1000 males
• This is what is usually referred to as "sex ratio" in Indian census data

Trends in Sex Ratio in India (K. Park)

• There has been a general declining trend over the 20th century, with a slight improvement in recent censuses
• The sex ratio remains consistently below 1000 (i.e., fewer females than males), indicating a "female deficit syndrome"

Sex Ratio at Birth by State (India 2016-18) - K. Park

Factors Affecting Sex Ratio in India

A. Biological / Natural Factors

1. Primary sex ratio imbalance: More male zygotes are conceived, but male embryos have higher in-utero mortality (spontaneous abortions), resulting in slightly more male births
2. Differential mortality: Males generally have higher age-specific mortality rates at all ages except reproductive years; in India, this is reversed due to neglect of females

B. Social and Cultural Factors

1. Male child preference: Strong son preference in Indian society due to economic, religious (son performs last rites), and cultural reasons leads to neglect of the girl child
2. Female infanticide: Killing of female neonates, historically practiced in some communities (e.g., Rajasthan, Tamil Nadu)
3. Female foeticide: Sex-selective abortion after prenatal sex determination - a major driver of low sex ratio at birth
4. Neglect of girl child: Higher female mortality at younger ages due to inadequate nutrition, healthcare, and immunization for girls

C. Technological Factors

1. Easy availability of sex determination tests (USG, amniocentesis): Has accelerated female foeticide despite being banned under the Pre-Conception and Pre-Natal Diagnostic Techniques (PC-PNDT) Act, 1994
2. Preconception sex selection facilities further distort the sex ratio even before birth

D. Socioeconomic Factors

1. Dowry system: Economic burden of dowry makes female children undesirable in many communities
2. Low literacy and education of women: Associated with lower status of women and higher female mortality
3. Poverty: Poor families more likely to neglect female children

E. Migration

1. Sex-selective migration: Males migrate more for work (especially to urban areas), altering the sex ratio in both source and destination areas
2. Urban sex ratio is often lower than rural due to male work migration

F. Enumeration Bias

1. Male bias in enumeration: Males may be over-counted or females under-reported, especially in areas with strong son preference

Consequences of Low Sex Ratio (Female Deficit Syndrome) - K. Park

• Strong indicator of gender inequity
• Higher maternal mortality (due to neglect and poor care)
• Female infanticide and foeticide
• Higher mortality of young girls
• Social problems: trafficking, child marriage

Key Exam Points

1. Primary sex ratio = at fertilization = ~1:1 (100:100)
2. Secondary sex ratio = at birth = ~105 males:100 females (globally); India = 899 F/1000 M (2016-18)
3. Tertiary sex ratio = in general population = India Census 2011 = 943 F/1000 M
4. India sex ratio has been declining historically - "female deficit syndrome"
5. Major causes: male child preference, female foeticide, infanticide, dowry, PC-PNDT Act violations
6. Worst states: Haryana, Delhi, Gujarat; Best: Chhattisgarh, Kerala
7. PC-PNDT Act 1994 was enacted to prevent sex-selective abortion

Injectable Contraceptives - K. Park

Definition

List of Injectable Contraceptives

A. Progestin-Only Injectables (POIs)

India's National Programme: Antara Programme (2017) introduced DMPA 150 mg (Antara) as an injectable contraceptive under the National Family Planning Programme - given at government health facilities every 3 months.

B. Combined Injectable Contraceptives (CICs) - Estrogen + Progestin

Mechanism of Action

• Primary: Suppresses ovulation (inhibits LH surge)
• Secondary:
  • Thickens cervical mucus (prevents sperm penetration)
  • Alters endometrial lining (prevents implantation)
  • Slows fallopian tube motility

Advantages of Injectable Contraceptives

1. High Efficacy

• Failure rate: <1% (Pearl index ~0.3) with perfect use
• One of the most effective reversible contraceptive methods
• No user-dependent daily action required

2. Long-Acting

• DMPA: protection for 3 months per injection
• NET-EN: protection for 2 months per injection
• Reduces frequency of clinic visits

3. Convenience and Privacy

• No daily pill to remember
• Coitus-independent - no action needed at the time of intercourse
• Discreet - partner may not know

4. Suitable for Breastfeeding Mothers

• Progestin-only injectables (DMPA, NET-EN) are safe during lactation
• Do not affect breast milk quantity or quality
• Can be started 6 weeks postpartum

5. No Estrogen-Related Side Effects (POIs)

• Safe in women with contraindications to estrogen:
  • Hypertension
  • Migraine with aura
  • Smokers over 35 years
  • History of DVT/PE

6. Non-Contraceptive Benefits

• Reduces dysmenorrhoea and menstrual cramps
• Reduces menorrhagia - leads to amenorrhoea (beneficial in anaemic women)
• Protective against endometrial cancer
• May reduce risk of PID (thickened mucus reduces ascending infection)
• Reduces sickle cell crises
• Useful in epilepsy (DMPA does not interact with anti-epileptics unlike OCP)

7. Reversible

• Fertility returns after stopping (though may be delayed - see disadvantages)

8. Programme Advantages (Public Health)

• Easy to administer by paramedical staff
• Does not require daily motivation
• Useful in low-literacy populations
• Part of India's Antara Programme - available free at government facilities

Disadvantages of Injectable Contraceptives

1. Menstrual Irregularities (Most Common Complaint)

• Irregular/unpredictable bleeding or spotting - especially in the first few months
• Amenorrhoea in up to 50-70% by 1 year (may be perceived as pregnancy or cause anxiety)
• This is the most common reason for discontinuation

2. Delayed Return of Fertility

• After stopping DMPA, ovulation may not return for 6-12 months (sometimes up to 18 months)
• Not suitable for women who wish to conceive soon
• Fertility returns faster with NET-EN (3-6 months delay)

3. No Protection Against STIs/HIV

• Does not protect against sexually transmitted infections
• Condoms must be used additionally if STI risk exists

4. Requires Healthcare Visit

• Must return to clinic every 2-3 months for injection
• Requires trained provider for administration
• Not self-administered (except DMPA-SC/Sayana Press)

5. Cannot be Discontinued Immediately

• Once injected, cannot be reversed or removed - side effects continue until the drug wears off (2-3 months)

6. Bone Mineral Density Reduction (DMPA)

• Long-term DMPA use associated with decreased bone mineral density
• Usually reversible after stopping
• WHO advises caution in adolescents (peak bone mass period) and perimenopausal women
• Not recommended for >2 years without review

7. Weight Gain

• Associated with weight gain (average 1-2 kg/year with DMPA)
• May deter some women from use

8. Other Side Effects

• Headache, mood changes, depression (rare)
• Breast tenderness
• Acne (rare)
• No protection during initial 7 days if not started within first 5 days of menstrual cycle

9. Not Suitable in Certain Conditions (Contraindications)

• Current/history of breast cancer
• Unexplained vaginal bleeding
• Severe liver disease
• Women wanting to conceive within 1-2 years

Summary Comparison Table

Key Exam Points

1. DMPA (150 mg IM, 3-monthly) = most widely used injectable contraceptive; marketed as Antara in India
2. NET-EN (200 mg IM, 2-monthly) = shorter duration, faster fertility return
3. Most common side effect = menstrual irregularity / amenorrhoea
4. Most common reason for discontinuation = menstrual irregularities
5. Unique advantage = safe in lactating women (progestin-only)
6. Unique disadvantage = delayed return of fertility and cannot be reversed once given
7. Antara Programme (2017) = India's national injectable contraceptive programme under Mission Parivar Vikas
8. Does not protect against STIs

Non-Contraceptive Benefits of Oral Contraceptive Pills (OCPs)

A. Menstrual Benefits

1. Reduction in Dysmenorrhoea (Painful Periods)

• OCPs suppress ovulation and reduce prostaglandin synthesis in the endometrium
• Result: significantly reduced menstrual cramps and pain
• One of the most common therapeutic uses of OCPs

2. Regulation of Menstrual Cycle

• OCPs produce regular, predictable, lighter periods
• Useful in women with irregular cycles (oligomenorrhoea, anovulatory cycles)
• Withdrawal bleeding is controlled and cycle length is predictable

3. Reduction of Menorrhagia (Heavy Bleeding)

• OCPs reduce menstrual blood loss by 40-50%
• Useful in treating menorrhagia and preventing iron deficiency anaemia
• Improvement in haemoglobin levels in anaemic women

4. Treatment of Premenstrual Syndrome (PMS) / PMDD

• Continuous or extended-cycle OCPs reduce PMS symptoms: bloating, mood swings, breast tenderness, headaches
• Drospirenone-containing pills particularly effective for PMDD

B. Protection Against Cancers

5. Reduced Risk of Ovarian Cancer

• 50% reduction in risk of epithelial ovarian cancer with OCP use
• Protection increases with duration of use (up to 5+ years)
• Protection persists for 10-20 years after stopping
• Mechanism: suppression of repeated ovulation (the "incessant ovulation" theory) reduces trauma and malignant transformation of ovarian epithelium

6. Reduced Risk of Endometrial Cancer

• 50% reduction in risk of endometrial (uterine) cancer
• Progestin component counteracts estrogen-induced endometrial proliferation
• Protection persists for at least 15 years after stopping
• Greatest benefit in nulliparous women (who are at higher natural risk)

7. Possible Reduction in Colorectal Cancer

• Some studies suggest modest protective effect against colorectal cancer
• Less firmly established than ovarian/endometrial protection

C. Gynaecological Benefits

8. Treatment of Endometriosis

• OCPs suppress endometrial tissue growth outside the uterus
• Reduce pain, dysmenorrhoea, and dyspareunia associated with endometriosis
• Used both as treatment and for prevention of recurrence post-surgery

9. Treatment of Polycystic Ovarian Syndrome (PCOS)

• OCPs are first-line treatment for PCOS
• Benefits in PCOS:
  • Regulate menstrual cycles
  • Reduce androgen levels (treat hirsutism and acne)
  • Prevent endometrial hyperplasia (from unopposed estrogen in anovulatory cycles)
  • Reduce ovarian cyst formation

10. Reduction in Benign Breast Disease

• Reduced risk of benign fibrocystic breast disease and fibroadenomas
• Reduces breast nodularity and mastalgia (breast pain)
• Note: OCPs do not reduce risk of breast cancer (slight increase in risk is a concern)

11. Reduction in Functional Ovarian Cysts

• Suppress ovulation → prevent formation of follicular and corpus luteum cysts
• Useful in women with recurrent functional ovarian cysts

12. Reduction in Uterine Fibroids

• Long-term OCP use associated with reduced risk of uterine leiomyomas (fibroids)
• Reduces fibroid-related menorrhagia

D. Protection Against Pelvic Inflammatory Disease (PID)

13. Reduced Risk and Severity of PID

• OCP-thickened cervical mucus acts as a barrier against ascending infections
• Reduces risk of salpingitis and upper genital tract infections
• Reduces risk of ectopic pregnancy (by preventing PID-related tubal damage)
• Note: OCPs do NOT protect against STIs/HIV transmission

E. Bone and Musculoskeletal Benefits

14. Prevention of Bone Loss / Osteoporosis

• Estrogen component helps maintain bone mineral density
• Particularly beneficial in:
  • Perimenopausal women
  • Women with hypoestrogenic states (athletic amenorrhoea, anorexia)
  • Adolescents with irregular cycles

F. Dermatological Benefits

15. Treatment of Acne and Hirsutism

• OCPs reduce androgen levels by:
  • Suppressing LH (reduces ovarian androgen production)
  • Increasing Sex Hormone Binding Globulin (SHBG) - reduces free testosterone
• Result: improvement in acne, oily skin, hirsutism
• Pills containing drospirenone, cyproterone acetate, or desogestrel most effective
• Several OCPs (e.g., Diane-35 with cyproterone) are licensed specifically for acne/hirsutism

G. Other Benefits

16. Reduced Risk of Ectopic Pregnancy

• By suppressing ovulation reliably, OCPs virtually eliminate the risk of ectopic pregnancy

17. Mittelschmerz Prevention

• Eliminates mid-cycle pain (ovulation pain) by suppressing ovulation

18. Relief from Rheumatoid Arthritis Symptoms

• Some studies show OCPs may reduce the risk and severity of rheumatoid arthritis
• Estrogen has mild anti-inflammatory effects

19. Treatment of Menstrual Migraine

• Extended-cycle or continuous OCP regimens can prevent menstrual migraines triggered by estrogen withdrawal
• (Note: OCPs with estrogen are contraindicated in migraine with aura due to stroke risk)

Summary Table

Key Exam Points

1. Two cancers reduced by 50%: Ovarian cancer and Endometrial cancer
2. PCOS - OCPs are first-line treatment
3. Acne/hirsutism - due to anti-androgenic effect (↑ SHBG, ↓ free testosterone)
4. PID - cervical mucus thickening reduces ascending infection
5. Anaemia - reduced menstrual blood loss improves haemoglobin
6. Endometriosis - suppresses ectopic endometrial growth
7. Protection against ovarian and endometrial cancer persists years after stopping OCPs
8. OCPs do NOT protect against breast cancer or STIs