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Protein Energy Malnutrition (PEM) - Park's Textbook of Preventive & Social Medicine

Definition

• Low birth weight (if the mother is malnourished)
• Poor growth in children
• High mortality between 12-24 months of age
• Estimated to be an underlying cause in 30% of deaths among children under 5

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Epidemiology (India - NFHS-4 Data)

• In low-income countries globally: 27% of children have low height-for-age (stunting), 17% have low weight-for-height
• Nutritional marasmus is more frequent than kwashiorkor in India
• Nearly 80% of PEM cases are mild to moderate; severe cases = 1-2% in preschool children

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Aetiology (Causes)

1. Inadequate food intake - both in quantity and quality (food gap)
2. Infections - diarrhoea, respiratory infections, measles, intestinal worms - these increase nutritional requirements while decreasing absorption/utilization

• Poor environmental conditions
• Large family size
• Poor maternal health
• Failure of lactation / premature termination of breastfeeding
• Use of over-diluted cow's milk
• Discarding cooking water from cereals
• Delayed supplementary feeding
• Adverse cultural practices in child-rearing and weaning

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Anthropometric Assessment

• Weight-for-Age (WFA) → identifies Underweight
• Height/Length-for-Age (HFA) → identifies Stunting (chronic malnutrition)
• Weight-for-Height (WFH) → identifies Wasting (acute malnutrition)

Underweight

• WFA Z-score < -2SD below WHO median
• Composite measure of stunting + wasting
• Even mild underweight increases mortality risk

Stunting

• Reflects cumulative effects of undernutrition and infections since birth (or before)
• High rates suggest bad environmental conditions and/or early malnutrition

Wasting

• Reflects current severe undernutrition or disease (acute)
• Greater frequency = more active problem

Severe Acute Malnutrition (SAM)

• Weight-for-height/length Z-score < -3SD from WHO median, OR
• Mid-upper arm circumference (MUAC) < 115 mm, OR
• Presence of nutritional oedema
• Children with SAM are 9 times more likely to die than well-nourished children

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Clinical Forms: Kwashiorkor vs Marasmus

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Early Detection of PEM

1. Growth charts - first indicator is underweight-for-age; can be used by field health workers
2. Arm (Mid-upper Arm) Circumference (MUAC):

   • 13.5 cm = satisfactory nutritional status

   • 12.5 - 13.5 cm = mild to moderate malnutrition
   • < 12.5 cm = severe malnutrition
   • (Cannot be used before age 1 year; between ages 1-5, it barely varies)

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Prevention of PEM

(a) Health Promotion

1. Measures for pregnant and lactating women (education, supplements)
2. Promotion of breastfeeding
3. Development of low-cost weaning foods; frequent feeding
4. Measures to improve family diet
5. Nutrition education - correct feeding practices
6. Home economics
7. Family planning and birth spacing
8. Improving family environment

(b) Specific Protection

1. Protein- and energy-rich foods (milk, eggs, fresh fruits)
2. Immunization
3. Food fortification

(c) Early Diagnosis and Treatment

1. Periodic surveillance / growth monitoring
2. Early diagnosis of growth lag
3. Early diagnosis and treatment of infections and diarrhoea
4. Programmes for early rehydration (ORS) in diarrhoea
5. Supplementary feeding during epidemics
6. Deworming of heavily infested children

(d) Rehabilitation

1. Nutritional rehabilitation services
2. Hospital treatment for severe cases
3. Follow-up care

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Key Points Summary (Park's Emphasis)

• PEM is a multifactorial problem - no single solution; interventions must be cause-specific
• The food gap (inadequate food intake + infections) is now the accepted primary cause, not simply "protein gap"
• Malnutrition is self-perpetuating across generations
• Infection and malnutrition form a vicious cycle acting synergistically
• India has a dual nutrition problem - undernutrition in the poor AND diseases of affluence in higher income groups
• Marasmus is more common than kwashiorkor in India

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SHORT NOTES - Park's Textbook of Preventive & Social Medicine

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1. MALNUTRITION (4 marks)

• Maternal depletion
• Low birth weight
• Anaemia
• Toxemias of pregnancy
• Postpartum haemorrhage
• High maternal and child mortality/morbidity

• Intrauterine period - very important nutritionally; adequate birth weight = lower mortality even in poor conditions
• Weaning period - severe malnutrition coincides with the age of weaning

• Inadequate food intake - "food gap" (primary cause; replaced old concept of "protein gap")
• Infections (diarrhoea, measles, respiratory infections, intestinal worms)
• Malnutrition and infection form a vicious cycle - each perpetuates the other
• Poor environmental conditions, large family size, poor maternal health, failure of lactation, premature termination of breastfeeding, adverse cultural practices

• 35.7% children underweight
• 38.4% stunted
• 21% wasted
• 18.5% low birth weight

• Direct: Supplementary feeding, iron/folic acid distribution, food fortification, nutrition education
• Indirect: Immunization, environmental sanitation, clean water, family planning, primary health care

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2. IRON DEFICIENCY ANAEMIA (4 marks)

• Haemoglobin formation (oxygen transport - central function)
• Brain development and function
• Regulation of body temperature
• Muscle activity (myoglobin)
• Catecholamine metabolism
• Component of cytochromes, catalase, enzyme systems
• Immune function (T-cells, antibody production)

• Haem-iron (better absorbed): Liver, meat, poultry, fish
• Non-haem iron (poor bioavailability): Cereals, green leafy vegetables, legumes, nuts, oilseeds, jaggery, dried fruits
• Inhibitors of absorption: Phytates (bran), phosphates (egg yolk), tannin (tea), oxalates - all prevalent in Indian vegetarian diet

• Absorbed from duodenum and upper small intestine in ferrous state
• Promoted by: Ascorbic acid, haem-iron foods
• Iron absorption from Indian diet < 5%
• Stored as plasma ferritin in liver, spleen, bone marrow, kidney

1. Stage 1: Decreased iron storage - no other detectable abnormalities
2. Stage 2 (Latent IDA): Iron stores exhausted, anaemia not yet present. Serum ferritin falls; transferrin saturation falls from 30% to <15%. Most widely prevalent stage in India.
3. Stage 3 (Overt IDA): Decreased circulating Hb due to impaired Hb synthesis - frank anaemia

• Serum ferritin (reflects storage)
• Serum transferrin saturation (normal >16%, normal value 30%)
• Haemoglobin estimation

• Impaired cell-mediated immunity
• Reduced resistance to infection
• Increased morbidity/mortality
• Diminished work performance

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3. NUTRITIONAL ASSESSMENT (3 marks)

• Signs and symptoms of nutritional deficiency in skin, hair, eyes, tongue, gums, nails
• Simple, inexpensive, most widely used

• Measurement of body dimensions
• Indices: Weight-for-Age (WFA), Height-for-Age (HFA), Weight-for-Height (WFH)
• Mid-upper arm circumference (MUAC)
• BMI = Weight(kg)/Height(m)²
• Inexpensive, non-invasive, widely applicable

• Blood tests: Hb, serum ferritin, transferrin saturation, serum albumin, serum vitamins
• Urine tests
• Detects sub-clinical deficiencies (prepathogenic stage)

• Assesses functional consequences - work capacity, immune function, cognitive development
• Anaemia → reduced work capacity; iron deficiency → impaired cognition

• 24-hour dietary recall
• Diet history/food frequency questionnaire
• Weighment method
• Identifies food consumption patterns

• Mortality rates, morbidity data linked to nutritional status
• Infant mortality rate as proxy for nutritional status

• Assessment of agricultural production, food supply, socioeconomic factors, cultural practices

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4. NUTRITIONAL ANAEMIA (3 marks)

• Most widespread micronutrient deficiency affecting all age groups
• 72.7% urban and 81.2% rural children under 3 years are anaemic
• 53.1% women anaemic (NFHS-4)
• 53.7% in urban; 54.3% in rural areas
• Children 6-59 months: 58.4% anaemic
• Bihar highest (87.6%); Nagaland lowest (44.3%)
• 19% of maternal deaths attributed to anaemia

• Poor dietary intake with low bioavailability (predominantly vegetarian Indian diet)
• Menstruation (women lose 12.5 mg iron per cycle)
• Malaria and hookworm infestation
• Rapid successive pregnancies
• IUD use (increases menstrual blood loss by 35-146%)

1. Pregnancy: Increases risk of maternal and foetal mortality/morbidity, abortions, premature births, postpartum haemorrhage, low birth weight
2. Infection: Iron deficiency impairs cellular immunity and increases susceptibility to infection
3. Work capacity: Even mild anaemia causes significant reduction in maximal work capacity and productivity

• Beneficiaries: Pregnant women, lactating mothers, children under 12 years
• Eligibility: Hb between 10-12 g/dl
• Dose for pregnant/lactating women: 100 mg elemental iron + 0.5 mg folic acid daily
• For children (1-5 years): 20 mg iron + 0.1 mg folic acid
• For children (6-10 years): 30 mg iron + 0.25 mg folic acid
• Severe anaemia (Hb < 10 g/dl): High dose iron or blood transfusion

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5. BALANCED DIET (3 marks)

1. Protein should be met first - amounts to 10-15% of daily energy intake
2. Fat requirement - limited to 15-30% of daily energy intake
3. Carbohydrates rich in natural fibre should constitute the remaining food energy
4. Requirements for micronutrients (vitamins and minerals) must be met

1. Cereals and millets
2. Pulses and legumes (protein source)
3. Milk and milk products
4. Meat, fish, eggs
5. Fruits and vegetables (vitamins, minerals, fibre)
6. Fats and oils (in limited amounts)
7. Sugar (limited)

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6. GROWTH CHART (2 marks)

• Developed through the Multicentre Growth Reference Study (MGRS) undertaken 1997-2003
• Conducted in 6 countries: Brazil, Ghana, India, Norway, Oman, USA
• 9,440 healthy breastfed infants and young children (0-60 months)
• Generated percentile and Z-score curves for: length/height-for-age, weight-for-age, weight-for-length/height, BMI-for-age
• India adopted WHO 2006 standards in 2009

• Combines the growth chart with information on immunization, nutrition, health
• Used by health workers at field level

1. Monitoring growth of individual child longitudinally
2. Early detection of growth faltering (PEM)
3. Tool for nutrition education for mothers
4. Assessment of effectiveness of nutrition interventions
5. Identifying children at risk
6. Assessment of community nutritional status
7. Used by Anganwadi workers and field health workers

• 13.5 cm = satisfactory nutritional status

• 12.5-13.5 cm = mild to moderate malnutrition
• <12.5 cm = severe malnutrition
• Cannot be used before age 1 year; barely varies between 1-5 years

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7. SALT FORTIFICATION WITH TRACE ELEMENTS (2 marks)

• Used for combating endemic goitre and Iodine Deficiency Disorders (IDD)
• Potassium iodate added to salt
• Universal Iodization of Salt (UIS) policy in India
• Effective and widely implemented

• Addresses widespread iron deficiency anaemia
• NIN (National Institute of Nutrition), Hyderabad has developed technology for this

• Addition of both iodine AND iron to salt simultaneously
• Technology developed; highly effective for dual deficiency

1. Consumed consistently as part of the regular daily diet by the target population
2. Amount of nutrient added must provide effective supplement for low consumers without hazardous excess for high consumers
3. Addition of nutrient must NOT cause noticeable change in taste, smell, appearance, or consistency
4. Cost of fortification must not raise the price beyond the reach of the needy population

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8. FOOD TOXINS (2 marks)

• Lathyrism - BOAA (Beta Oxalyl Amino Alanine) in Lathyrus sativus
• Endemic ascites - Pyrrolizidine alkaloids

• Botulism (Clostridium botulinum)
• Staphylococcal poisoning

• Produced by Aspergillus flavus and A. parasiticus
• Infest: groundnut, maize, parboiled rice, sorghum, wheat, cotton seed, tapioca
• Occurs under conditions of improper storage
• Aflatoxin B1 and G1 = most potent hepatotoxins and carcinogens

• Produced by Claviceps purpurea fungus on rye and other cereals
• Causes ergotism: vasoconstriction → gangrene, convulsions

• Heavy metals: mercury (fish), cadmium (shellfish), lead (canned food)
• Pesticide residues (DDT, BHC)
• Petroleum derivatives and solvents (e.g., Tricresyl phosphate/TCP)
• Migrant chemicals from packaging materials
• Asbestos

• Bacterial (typhoid, salmonellosis, botulism, E. coli diarrhoea)
• Viral (hepatitis A and E, Norovirus)
• Parasitic (Taeniasis, Ascariasis, Amoebiasis)

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9. ROLE OF DIET AND LIPOPROTEIN IN CHD (2 marks)

• Most serum cholesterol (~50%) is in LDL
• A low HDL/LDL ratio favours atheroma development → CHD

• Saturated fatty acids (C12, C14, C16): Raise plasma cholesterol; high intake → increased CHD risk. Sources: Animal fats, coconut oil
• Polyunsaturated fatty acids (PUFA) (linoleic, arachidonic acid): Lower plasma cholesterol by reducing VLDL synthesis; also inhibit platelet aggregation → prevent thrombus formation

• Arachidonic acid metabolizes in vascular endothelium to form:
  • Prostacyclin → inhibits platelet aggregation + relaxes coronary vessels (protective)
  • Thromboxane → induces platelet aggregation + vasoconstriction (harmful)
• Linoleic acid (precursor of arachidonic acid) is the body's best protection against CHD

• Fat calories: < 30% of total calories
• Replace saturated fats with PUFA
• Reduce dietary cholesterol
• Increase fibre intake

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10. ICDS PROGRAMME (2 marks)

• Preschool children below 6 years
• Adolescent girls 11-18 years
• Pregnant and lactating mothers

1. Supplementary nutrition
2. Immunization
3. Health check-up
4. Referral services
5. Nutrition and health education
6. Non-formal pre-school education

• Supplementary nutrition
• Vitamin A prophylaxis
• Iron and folic acid distribution

• Anganwadi Worker (AWW): Village-level worker; covers population of 400-800 (mini anganwadi: 150-400)
• Mukhyasevika: Supervises Anganwadis
• CDPO (Child Development Project Officer): Field-level supervision
• Network of Mahila Mandals supports AWWs

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11. IRON REQUIREMENT IN PREGNANCY (2 marks)

• Rapid expansion of red cell mass
• Foetal iron requirements
• Blood loss during delivery
• Iron absorption increases during pregnancy to meet demands
• But despite increased absorption, dietary supply is often insufficient

• Pregnant women: 27 mg/day
• Non-pregnant women: 29 mg/day
• Lactating women: 21 mg/day

• Iron absorption from habitual Indian diet <5% (bioavailability poor due to vegetarian diet)
• Women already enter pregnancy with low iron stores
• Close successive pregnancies deplete iron stores further

• 100 mg elemental iron + 0.5 mg folic acid tablet - taken daily for 100 days (from second trimester)
• Administered by ANM/ASHA

• Increased maternal mortality (19% maternal deaths in India attributed to anaemia)
• Abortions, premature births
• Postpartum haemorrhage
• Low birth weight
• Impaired neonatal iron stores

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12. ENDEMIC FLUOROSIS (2 marks)

• Occurs when excess fluoride is ingested during tooth calcification (first 7 years of life)
• Characterized by "mottling" of dental enamel (reported at levels >1.5 mg/L)
• Early sign: Teeth lose shiny appearance → chalk-white patches develop
• Later: White patches turn yellow, then brown/black
• Severe cases: Loss of enamel gives corroded appearance
• Mottling best seen on upper jaw incisors
• Confined almost entirely to permanent teeth

• Associated with lifetime daily intake of 3.0-6.0 mg/L or more
• Heavy fluoride deposition in skeleton
• At >10 mg/L: Crippling fluorosis
• Leads to permanent disability

• Newer form - characterized by genu valgum (knock-knees) and osteoporosis of lower limbs
• Reported in Andhra Pradesh and Tamil Nadu
• Seen among people whose staple is sorghum (jowar) - sorghum promotes higher fluoride retention

1. Change water source to one with lower fluoride (0.5-0.8 mg/L) - surface water has less fluoride than ground water
2. Nalgonda technique for defluoridation: Developed by National Environmental Engineering Research Institute, Nagpur - involves addition of lime and alum, followed by flocculation, sedimentation, filtration
3. Do NOT prescribe fluoride supplements in endemic areas
4. Fluoride toothpaste not recommended for children under 6 years in endemic fluorosis areas

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13. MID-DAY MEAL PROGRAMME (1 mark)

1. Should be a supplement (not substitute) to the home diet
2. Should supply at least 1/3 of total energy requirement and 1/2 of protein need
3. Cost should be reasonably low
4. Preparation should be simple (no complicated cooking)
5. Locally available foods should be used as far as possible
6. Food must appeal to the children's taste

• Cooked meal providing: 300 kcal and 8-12 g protein per child
• 250 feeding days per year
• Centrally sponsored scheme

• Improves school enrolment and attendance
• Reduces dropout rates
• Improves nutritional status
• Encourages social equity (children of all communities eat together)

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14. EPIDEMIC DROPSY (1 mark)

• Sudden, non-inflammatory, bilateral swelling of legs (dropsy)
• Often associated with diarrhoea
• Dyspnoea, cardiac failure
• Glaucoma (some patients)
• Occurs at all ages EXCEPT breastfed infants
• Mortality: 5-50%

• Seeds of Argemone mexicana closely resemble mustard seeds
• Plant grows wild in India with prickly leaves and bright yellow flowers
• Crops harvested together in March when both mature simultaneously
• Also occurs through deliberate adulteration by unscrupulous dealers

1. Nitric acid test: Addition of nitric acid → brown to orange-red colour; positive when argemone oil >0.25%
2. Paper chromatography: Most sensitive - detects argemone oil up to 0.0001% in all edible oils

• Remove argemone weeds from oil-seed crops at source
• Strict enforcement of the Prevention of Food Adulteration Act

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15. LATHYRISM (1 mark)

1. Legislative: Banning cultivation and sale of Khesari dhal (banned in several states)
2. Steeping/soaking method: Soak lathyrus in hot water and discard water - removes water-soluble BOAA toxin
3. Vitamin C supplementation (protective role)
4. Dietary diversification - not relying solely on Khesari dhal
5. Socio-economic development - the ultimate solution (poverty drives consumption)

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16. PROTEIN ENERGY MALNUTRITION (1 mark)

• Growth chart (first indicator = underweight-for-age)
• MUAC: >13.5 cm = normal; 12.5-13.5 cm = mild-moderate PEM; <12.5 cm = severe PEM

1. Health promotion - breastfeeding, weaning foods, nutrition education, family planning
2. Specific protection - protein and energy-rich foods, immunization, food fortification
3. Early diagnosis and treatment - growth monitoring, deworming, ORS for diarrhoea
4. Rehabilitation - nutritional rehabilitation services, hospital treatment, follow-up

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INTEGRATED CHILD DEVELOPMENT SERVICES (ICDS) PROGRAMME

Park's Textbook of Preventive and Social Medicine

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Background and Introduction

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Objectives of ICDS

1. Improve the nutritional and health status of children in the age group 0-6 years
2. Lay the foundation for proper psychological, physical, and social development of the child
3. Reduce the incidence of mortality, morbidity, malnutrition, and school dropout
4. Achieve effective coordination of policy and implementation amongst various departments to promote child development
5. Enhance the capability of the mother to look after the normal health and nutritional needs of the child through proper nutrition and health education

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Beneficiaries

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Six Services Provided by ICDS

• Supplementary nutrition
• Vitamin A prophylaxis
• Iron and folic acid (IFA) distribution

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Administrative Structure

Project Areas

• "Community development block" in rural areas
• "Tribal development block" in tribal areas
• "Group of slums" in urban areas

• Rural/urban project: ~1,00,000 population
• Tribal project: ~35,000 population
• Rural project: ~100 villages; Tribal project: ~50 villages

• 305.09 lakh children as pre-school education beneficiaries
• 836.25 lakh supplementary nutrition beneficiaries

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Personnel / Functionaries

1. Anganwadi Worker (AWW)

• "Angan" literally means a courtyard
• The focal point for delivery of integrated early childhood services
• Selected from the community she is expected to serve
• Undergoes 4 months training in health, nutrition, and child development
• Part-time worker - paid an honorarium of Rs. 1500/month

• Health check-up including maintenance of growth chart
• Immunization
• Supplementary nutrition
• Health and nutrition education to mothers
• Non-formal pre-school education (for 3-6 year olds)
• Referral services
• Direct link to children and mothers
• Assists CDPO in survey of community and beneficiaries
• Maintains records of immunization, feeding, pre-school attendance
• Assists PHC staff in providing health services
• Works for community-based activities (e.g., family planning)
• Liaises with block administrator, local school, health staff

2. Mukhya Sevika (Supervisor)

• Supervises 20-25 Anganwadis
• Acts as mentor to AWWs
• Assists in record keeping, visits of health personnel, and organizing community visits
• Provides on-the-job training to AWWs

3. Child Development Project Officer (CDPO)

• Field-level supervision officer
• In charge of 4 Supervisors (Mukhya Sevikas) and 100 AWWs

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Supplementary Nutrition

• Dose: 300 kcal and 10 g protein per beneficiary per day (through Anganwadi centres)
• Children (6 months - 3 years), severely malnourished children, pregnant/lactating mothers receive supplements
• Feeding for 300 days/year
• Food is prepared and served at the Anganwadi centre

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Impact of ICDS

• Increased birth weight
• Reduced incidence of malnutrition
• Increased immunization coverage
• Reduced infant and child mortality rates in areas covered by ICDS

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ICDS-linked Schemes

(a) Kishori Shakti Yojana (KSY)

• Implemented through ICDS infrastructure
• Targets adolescent girls aged 11-18 years
• Addresses: Self development, nutrition and health status, literacy, numerical skills, vocational skills

(b) Rajiv Gandhi Scheme for Empowerment of Adolescent Girls - "SABLA"

• For age group 11-18 years
• Goal: Improve nutritional and health status of adolescent girls

(c) Nutrition Programme for Adolescent Girls (NPAG)

• Approved in 2009-10, pilot project basis
• Implemented in 51 identified districts
• Beneficiaries: Undernourished girls aged 11-19 years with body weight < 30 kg (11-15 yrs) or < 35 kg (15-19 yrs)
• 6 kg of free food grain per beneficiary per month
• Implemented through ICDS scheme infrastructure

(d) Indira Gandhi Matritva Sahyog Yojana (IGMSY)

• Conditional cash transfer to pregnant and lactating mothers
• Aim: Improve nutritional and health status of mothers

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Poshan Abhiyan (National Nutrition Mission)

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ICDS as a Direct Nutrition Intervention

• Universal immunization + ORT + ICDS together have a considerable impact on child survival and extreme forms of malnutrition
• Growth monitoring for 0-3 years with close mother involvement
• Reaching adolescent girls through ICDS to prepare them for safe motherhood
• Ensuring better antenatal coverage to reduce low birth weight

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Significance / Importance of ICDS

• Largest integrated programme for early childhood in the world
• Addresses malnutrition at its roots - during the most critical period of growth (0-6 years)
• Multi-sectoral approach: health + nutrition + education + social welfare together
• Uses community-based delivery through Anganwadi workers (from the same community)
• Serves as a safety net for the most vulnerable - tribal, rural poor, urban slum children
• Provides a platform for adolescent girl health and empowerment
• The Government is committed to universalizing ICDS to reach every child in India

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ROLE OF DIET AND LIPOPROTEIN IN CORONARY HEART DISEASE (CHD)

Park's Textbook of Preventive and Social Medicine

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The Triangular Relationship

        HABITUAL DIET
             ↓
    BLOOD CHOLESTEROL LEVELS
             ↓
    CORONARY HEART DISEASE

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I. CHOLESTEROL

• Occurs in all foods of animal origin
• Part is synthesized endogenously in the body

1. Amount absorbed from food
2. Amount synthesized in the body (endogenous)
3. Rate of catabolism and excretion in bile
4. Intestinal reabsorption of bile acids
5. Equilibrium between plasma and tissues

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II. LIPOPROTEINS

Classification of Lipoproteins

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LDL - The "Bad" Lipoprotein

• Functions in the delivery of cholesterol to body cells
• Excessive LDL → accumulation of cholesterol in smooth muscle cells of the vascular wall
• Directly involved in the arteriosclerotic process → atherosclerosis → CHD
• High LDL level is a major risk factor for CHD

HDL - The "Good" Lipoprotein

• Functions in the removal of cholesterol from cells (reverse cholesterol transport)
• Underlies the blood vessel's capacity to resist cholesterol deposition
• Higher HDL levels = more protection against CHD (from long-term observations)
• Low HDL/LDL ratio favours development of atheroma → CHD

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III. FATTY ACIDS AND THEIR ROLE

A. Saturated Fatty Acids (SFA) - Harmful

• In populations with high plasma cholesterol, there is also high consumption of saturated fats
• High intake of SFA over several weeks/months causes increase in plasma cholesterol
• Cholesterol-raising effect is mainly produced by:
  • C12 (lauric acid)
  • C14 (myristic acid)
  • C16 (palmitic acid)
• Stearic acid and fatty acids with <12 carbon atoms have smaller effect
• Mechanism: possibly act on cholesterol synthesis
• Sources: ghee, butter, coconut oil, red meat, palm oil

B. Polyunsaturated Fatty Acids (PUFA) - Protective

• Lower plasma cholesterol (mechanism: reduced synthesis of VLDL)
• Additionally inhibit platelet aggregation → prevent thrombus formation
• Key PUFA: linoleic acid, arachidonic acid
• A low HDL/LDL ratio induced by PUFA shift is protective against CHD

Prostacyclin - Thromboxane Pathway (Arachidonic Acid)

• Linoleic acid (the main precursor of arachidonic acid) is therefore regarded as "the body's best bulwark against CHD"
• Aspirin and other drugs inhibit the cycloxygenase step → reduce thromboxane formation → anti-platelet effect
• Essential fatty acids have come to be regarded as of major importance in clinical nutrition

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IV. TRIGLYCERIDES

• In a large proportion of individuals with raised cholesterol, blood triglycerides (TG) are also markedly increased
• TG levels act as a significant independent risk factor for CHD
• Both cholesterol and TG are associated with specific proteins in plasma to form lipoproteins

• Most important determinant = activity of lipoprotein lipase in endothelial lining of capillaries
• This enzyme removes TG from VLDL and converts them to lipoproteins of higher density
• In genetic disorders, this enzyme may be absent
• In diabetes - reduced lipoprotein lipase activity → high TG concentrations
• Ischaemic myocardium may not metabolize all fatty acids equally; accumulation of some fatty acids may be more associated with sudden cardiac death

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V. CARBOHYDRATES

• CHD rates are lowest in populations eating high carbohydrate diets
• Historical trend (USA): CHD mortality was low until ~1920 → steady increase as dietary carbohydrate consumption decreased after 1920 → decline again began 1968
• High complex carbohydrate diet appears to decrease risk of CHD
• Dietary fibre intake shows an inverse association with risk of CHD (higher fibre = lower CHD)
• Neither high carbohydrate nor high sucrose feeding has induced atherosclerosis in animal studies
• A decrease in serum cholesterol was observed during vegetable feeding periods in studies

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VI. SALT AND HYPERTENSION (indirect CHD risk)

• Good and consistent correlation between high dietary sodium intake and hypertension
• Highest incidence of hypertension: North Japan (sodium intake >400 mmol/day)
• Primitive societies with <60 mmol/day sodium intake: virtually no hypertension
• Hypertension → major independent risk factor for CHD
• Low-sodium diet (<10 mmol/day) can successfully treat hypertension

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VII. DIETARY RECOMMENDATIONS TO PREVENT CHD

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VIII. Genetic vs Dietary Interaction

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