Lecture 20- Human nutrition: diseases and conditions influencing nutrition Flashcards
What is fetal programming?
- Process by which the environment encountered before birth (or in infancy) will shape the long term control of tissue physiology and homeostasis
- Started in the ‘80’s after the discovery of strong associations between early life events & cardiac disease
- But first reported in 1964 when noted that heart disease increased in individuals with siblings that were stillborn or died in infancy
- Particularly susceptible during rapid growth phases
Is fetal programming present in all species?
- Exists in all species
- Sex of crocodilians is determined by programming NOT chromosomes
- Via temperatures
- Feeding a zinc deficient diet to pregnant mice has consequences that will last 3 generations!
- Impaired immune function
- Wool follicle growth is impacted by nutrition
- First wave of secondary follicles develop in the last trimester
What is known about human fetal programming?
- However growth of human fetus (unlike other species) is less susceptible to this and they are not particularly sensitive to variations in maternal diet
- This is not to say that other factors are not influenced
- Extensive famine will influence birthweight but the effects are relatively small
- BUT restriction or deficiencies in the maternal diet will change physiology and the initiation of disease processes later in life
- However, this is a COMPLEX process with nutrient-gene interactions during a period of plasticity
- Associations can be crude and may not reveal true aspects of the programming event
Can non-nutrient components be involved in fetal programming?
- Non-nutrient components may also be involved
- E.g. hormone agonists such as Vinclozolin (a fungicide used in fruit production) has anti-androgenic properties and exposure can cause feminisation of male pups in rats
- Effects not seen in humans but exposure can be associated with testicular abnormalities in adults
What was the dutch hunger winter?
- Low protein diets in pregnant rats can reduce birthweight & increase blood pressure & impaired glucose tolerance in adult offspring
- Similar responses in guinea pigs & sheep
- Difficult to measure in humans
- ‘Dutch Hunger winter’
- 5 months of severe famine at the end of WW2
- Limited duration & abrupt onset & relief
- Ongoing studies
- Showed altered birthweights, glucose intolerance, obesity, altered lipid profiles, altered coagulation, reduced cognitive function and increased risk of coronary heart disease
What was the dutch famine?
- Grandmaternal famine exposure during gestation was associated with increased adiposity and poorer health
- Can be passed onto future generations
- Women conceived during the famine had 5 x increased risk of breast cancer
- This was in small numbers
- BUT there is evidence of a thrifty genotype
- Women exposed to famine have more children, more twins & reproduced younger
- Trade off – investment between increased fertility & body maintenance
Is maternal undernutrition in early pregnancy also as important?
- However maternal undernutrition in early pregnancy is unlikely to result in growth issues for the fetus as the fetal nutrient requirements are low
- Balance of nutrients is important
- Protein to energy ratio
- E.g. reduced folate can influence AA synthesis
- Importance of taurine for pancreatic β cell development that cannot be reversed with supplemental taurine to β cells in culture but is reversed if supplemented to the mother
What is the connection of birthweight and obesity?
• Positive association between birthweight & adiposity later in life (BMI)
• Modest but consistent across populations
-heavier babies heavier later
• Also correlation between birthweight & adult height
• Breastfeeding is associated with lower risk of obesity later in life
• Maternal undernutrition can lead to the development of overeating and diminished exercise in offspring
What was the China study?
• Study between Oxford & Cornell
• In The China Study, Dr. T. Colin Campbell details the connection
between nutrition and heart disease, diabetes, and cancer.
• The report also examines the source of nutritional confusion produced by powerful lobbies, government entities, and opportunistic scientists.
• The New York Times has recognized the study as the “Grand Prix of epidemiology” and the “most comprehensive large study ever undertaken of the relationship between diet and the risk of developing disease.”
• The China Study is not a diet book. Dr. Campbell cuts through the haze of misinformation and delivers an insightful message to anyone living with cancer, diabetes, heart disease, obesity, and those concerned with the effects of aging.
What is the book that came out of the China study?
• Best selling nutrition book (USA)
• Examines relationship between consumption of animal products &
illness
• Conclude that vegan diets (0 mg cholesterol) escape or reduce the risk of many diseases
• Book is loosely based on the study
• 1973-1975
• Mortality rates from cancer & other chronic diseases from 65 counties in China
• Correlated to data from 1983-1984 dietary surveys (& blood work) from 100 people in each county
-Is it true???, another study:• “women’s health initiative” USA
• Data from ~160,000 women (50-79 years)
• Concluded that low dietary fat (including animal fats) does not reduce the incidence of breast & colorectal cancer or coronary heart disease, stroke or vascular disease= refuted the china study
What is to remember about data manipulation?
- 50% relative difference is a headline grabber, (compared to 1%) but can be misleading
- From below data you could also say 99% of group A & 98% of group B did not develop the disease
- Would you alter your lifestyle fro 1% reduced risk?
What is the nutrition in disease management?
- Malnutrition can contribute to increased vulnerability to infection (of all diseases)
- Virus increases nutritional needs?
- But decreases appetite & intake
- Impairs digestion & causes malabsorption
- Results in weight loss • “thindisease’
- ‘perfect’ diet unknown
- Including animal derived foods results in better health outcomes • Roleoffunctionalfoods?
- People without constant access to food are more vulnerable to HIV
What are the detox diets?
• Do our bodies really get clogged up with toxins?
• Do we not have a liver for that? • 1800 + books on amazon
• 5,630,000 google hits
• Liver needs energy (etc.) to function and
cleanse so would a nutrient restricted (e.g. lemon water) diet assist this?
• High calorie juices?= not that good for you
-marketing only
-fat, sick and nearly dead= watch
-liver needs energy to function!
What are the nutritions myths surrounding dairy?
- Dairy consumption increases mucus production
• Dates back to the 12th century (wives tale!)
• No evidence (2004 review)
• Not linked to asthma - Lactose intolerance Vs lactose maldigestion
• Different conditions
• People with maldigestion can drink ~2 glasses of milk and feel ok & can eat cheese etc. - Dairy products cause acne
• No scientific link
• Acne is not caused by diet (generally) - Actually, dairy consumption may improve insulin sensitivity (T2 diabetes)
- Meta-analysis demonstrated either no effect of dairy when consumed for
What is the myth about carbs after 5pm?
- Not-eating carbs after 5pm will help you lose weight • No evidence (review of 4800 papers)
- But yes it will if you are reducing intake overall • Timing is not important, total consumption is
What is marasmus?
- Marasmus
- Protein-energy malnutrition
- Starvation of infant or young child
- Marasmus = wasting
- Little to no adipose tissue, weight
What is Kwashiorkor?
- Kwashiorkor
- Recognised in the ‘50’s
- Generalised oedema
- Miserable / ill children
- Changes to skin pigmentation which later cracks & peels • Hair thins, turns blonde/red/grey
- Diarrhoea
- Enlarged liver which fails to make albumin
- Develops faster than marasmus
- Child may not be underweight
- Acute depletion of liver protein?
- Due to very low protein diet? Free radical damage?
What is the connection between cancer and nutrition
• Because carcinogenesis occurs over years, most data linking diet and cancer is epidemiological (case control, cohort, or cross-sectional studies)
• It is estimated that one third of the cancer deaths each year in the US can be attributed to nutrition and other lifestyle factors (not including smoking)
• Complex relationship
• Dietary carcinogens: naturally occurring and added in food preparation and
preservation
• Inhibitors of carcinogenesis: antioxidants, phytochemicals
• Enhancers of carcinogenesis
• Latency period between initiation and promotion
What is the connection between energy intake and cancer?
- Energy restriction inhibits cancer and extends life span in animals
- Positive associations between overweight and cancers of the breast, endometrium, kidney, colon, prostate, and others
- Overweight increases risk of cancer recurrence and decreases survival • Physical activity is inversely associated with cancer
What is the connection between protein and cancer?
- Protein
- Difficult to isolate effects of protein, as↑ protein diets are ↑ in fat &↓ in fiber
- Low protein diets seem to reduce the risk of cancer, while risk is ↑by very high protein intakes
- ↑ meat intake is associated with ↑ risk of colon cancer and advanced prostate cancer