Nutrition & Health Flashcards
(39 cards)
1
Q
What are the criteria for a nutrient to be classified as indispensable/essential?
A
- Must be required for growth, health or survival
- Absence/deficiency of substance in diet will lead to characteristic signs of deficiency disease
- Growth failure & signs of deficiencies can only be prevented by:
a. The nutrient itself
b. A precursor of nutrient - Not synthesised in the body & is required for critical function in body
- When intake is below a critical intake level - the growth response & severity of signs of deficiency is proportional to amount consumed
2
Q
What are the exceptions to the criteria for nutrient classification as indispensable/essential?
A
- Some can be synthesized in the body from a precursor (e.g. VitA or Niacin)
- De novo synthesis in the body (Vit D from sunlight)
- Synthesis by microbes in the gut (Vit K)
3
Q
What are examples of dispensable/non-essential nutrients?
A
- Non-essential Amino Acids
- Specific fats/CHO
- Alcohol
- Food additives
4
Q
What are 2 non-essential nutrients that still have health benefits?
A
- Fluoride:
o Low dosages = prophylactic decrease in dental cavities
o Too much leads to fluorosis - Fiber:
o Insoluble (whole wheat, bran):
- NB for gastro-intestinal function
- Prevents constipation & colon cancer
o Soluble (oat bran):
- Fermentation leads to short chain fatty acids which :
• Provide energy for colonocytes
• Decrease plasma cholesterol
• V important in moderating the comp of microbiome
5
Q
What are conditionally essential nutrients?
A
Essential in some populations but not in others
6
Q
What are examples of populations with conditionally essential nutrient needs?
A
- Premature infants:
o Have immature metabolic enzyme systems
o They can’t synthesise/digest all the nutrients needed - Hyper-catabolic patients:
o Increased protein degradation
o Decreased protein synthesis
o i.e. Glutamine use > Glutamine production
7
Q
What are Dietary Reference Intakes (DRIs)?
A
Is a collective term, including:
- Estimated Average Requirement (EAR) - Recommended Dietary Allowance (RDA) - Adequate Intake (AI) - Tolerable upper Intake Level (UL)
8
Q
What is the Estimated Average Requirement?
A
- Intake that meets the estimated needs of a nutrient of 50% of individuals in a specified gender group, at the given life-stage.
- Includes an adjustment for an assumed bioavailability of respective nutrient
- Used for setting the RDA
- Insufficient scientific evidence for EAR -> no RDA set
9
Q
What is the Recommended Dietary Allowances?
A
- Intake that meets the nutrient needs of almost all individuals in that gender group, at the given life-stage
- EAR + 2SD (standard deviations)
- RDA applies to individuals, not to groups
- Goal for dietary intake for the individual
10
Q
What is Adequate Intake?
A
- Experimentally derived intake levels or approximations of observed mean nutrient intakes by a group of healthy people, who have normal circulating nutrient blood concentrations, growth, or other functional indicators of health.
- AI recommendation when scientific evidence is inadequate to set an EAR
- Indicates that substantially more research is needed to established EAR & RDA
11
Q
What is the Tolerable Upper Intake Level?
A
- Max nutrient intake by an individual, which is unlikely to pose risks of adverse health effects in almost all individuals in a specified group.
- Set to protect the most sensitive individuals in the healthy general population
- Applies to chronic daily use
- Not a recommended level of intake
- Contains NOAEL & LOAEL
12
Q
When did Tolerable Upper Intake Levels become necessary?
A
When food fortification occurred/became mandatory in many countries & Supplementation became available on the market (allowed people to meet these max levels).
13
Q
What is a NOAEL?
A
- No-Observed-Adverse-Effect-Level (NOAEL):
o Highest intake/experimental oral dose of a nutrient at which no adverse effects have been observed in the individuals investigated
o This does not mean that there is no potential for adverse effects with such a high intake.
14
Q
What is a LOAEL?
A
- Lowest-Observed-Adverse-Effect-Level (LOAEL):
o The lowest intake at which an adverse effect has been identified.
o If insufficient data to set a NOAEL - use LOAEL as guideline.
15
Q
What are the applications of DRIs?
A
- Can use it to plan or assess a diet
- DRIs were purposefully developed for applying standards to groups & individuals - before they only had the RDA which was only for groups of people who were healthy and not any single individual.
- Food Labels
16
Q
What are Dietary Goals?
A
- Quantitative dietary recommendations
- Intended for use by health professionals
17
Q
What are Dietary Guidelines?
A
- Qualitative dietary guidance – in terms of food not nutrients
- Intended for use by the general public
- Public can use to assess/plan their own diet
- Express DRIs and dietary goals in terms of food
- Simple, practical advice for optimal food choices
- Each country has own set of guidelines
18
Q
What do all diets emphasise limitation of?
A
- Refined starches
- Added sugars, sweets
- SSBs (Sugar-sweetened beverages)
- Bakery Foods
- Processed Meats
- Fast foods & takeaways
- Trans-fats, salts
19
Q
What is nutritional genomics?
A
= [Genotype + Environment (Diet)] which form a functional phenotype
- Health-disease continuum is a player
- Is an overarching term for:
o Nutrigenetics
o Epigenetics
o Nutrigenomics
20
Q
What is Nutrigenomics?
A
The effect of the environment (nutrients) on gene expression
- Nutrients can influence production of hormones
- Hormones can influence signal transduction & production of transcription factors
- These can increase/decrease transcription
21
Q
What is the nutrigenomic effect of Vitamin A, D and poly-unsaturated fatty-acids?
A
- They interact with intracellular receptors which influence transcription factors -> influence transcription via promoter area
22
Q
What is the nutrigenomic effect of Vitamin C?
A
(An anti-oxidant) It prevents oxidative damage of RNA
23
Q
What is the nutrigenomic effect of Zinc?
A
Necessary for certain transcription factors in the promote area & influences DNA binding.
24
Q
What is the nutrigenomic effect of Vitamin K?
A
Important for post-translational mods of certain proteins in order to become biologically active.
25
What is Epigenetics?
- Heritable, but reversible changes in the expression of a gene or trait
- Don't involve mutations/SNPs - i.e. no changes in DNA sequence
- Examples:
o Histone Modification
o Methylation
26
What is Nutrigenetics?
The study of the environmental (dietary) effects on phenotype outcomes.
o Studies the effect of genotype x diet on a phenotype indicator
27
What is Precision Nutrition?
- Dietary changes/recommendations based on genotype
- Pursues development of comprehensive & dynamic nutritional recommendations based on shifting, interacting parameters in a persons internal & external environment throughout life
28
What are some ethical issues related to Nutrigenetics?
1. Direct-to-consumer marketing (DTC): Cutting out the health professional, needs consumer education
2. Discrimination: Loss of privacy, employment, social discrimination
3. Children: Testing for adult onset disorders?
4. ‘unintended information’ - Finding out about Alzheimers etc.
5. Cost: Accessible for all?
6. Trigger unhealthy quests for health
29
What is a monogenic disease?
- High penetrance
- Single gene involved
- E.g. cystic fibrosis
30
What is a polygenic disease?
- Low penetrance
- Many genes (polymorphisms) involved
- E.g. Diabetes, cancer, CVD
31
What type of evidence is needed for genotype based nutrition?
Evidence should:
1. Predict a robust increase or decrease in disease risk or improvement in treatment outcome in relation to a specific dietary pattern, food or nutrient intake
2. Confirm causality – subsequent genotype-based intervention must decrease disease risk or improve treatment outcome
o Associations from observational studies need to be verified in dietary intervention studies to provide evidence of causality
32
Types of Genetic screening for genotype based Nutrition
1. Susceptibility screening for prevention
a. Screen healthy people at risk (due to family history, other indicators) for a disease
b. Screen healthy people in general for alleles associated with common multifactorial diseases (obesity, CVD, etc.)
2. Screening individuals to optimize treatment outcomes
a. Remember contribution of a single SNP to disease risk is small
b. A SNP can be good or bad
33
What is the Candidate Gene Approach to Nutrigenetics?
- Hypothesis driven
- Relies on current understanding of biology & physiology of disease
- Known/presumed biological function/metabolic pathways
34
What is the Genome Wide Association Approach to Nutrigenetics?
- Investigates the entire genome
- No prior assumptions
- Identify previously unsuspected loci associated with disease
- Can narrow down locus more accurately
- BEWARE of incidentalomics:
o Unexpected incidental findings (false +’s)
35
What are some contributors to chronic inflammation?
```
o Autoimmune effects
o Excess body fat
o Genomics & epigenetics
o Infection
o Smoking
o Inflammatory diet
o Microbiome
o Physical trauma
o Antigens
o Lack of sleep
o Emotional upsets/stress
```
36
What are some biomarkers associated with chronic inflammation?
o Mediators involved in or produced as a result of inflammatory process
o NB to use valid markers – reflect inflammatory status & be predictive of future health status
o No consensus as to which markers best represent low-grade I or differentiate between acute & chronic I
o Ongoing research
37
What is an inflammatory score (IS)
- IS of -1 = Max anti-inflammatory effect
| - IS of +1 = Max pro-inflammatory effect
38
Example of a pro-inflammatory dietary pattern
Wester Type diet:
- Increased: Red meat, fat dairy products, refined grains, sugars
- Decreased: Fruit, veg, legumes
- Energy dense, nutrient poor
- 0 < IS < +1
- Core Mechanisms:
o Excess Energy:
• Results in weight gain -> central obesity -> activates inflammatory pathways
o Increased Saturated Fats:
• Increased SF -> increased weight & adipose tissue
• Changes in membrane & lipid raft comp -> altering cell signalling
• Activates inflammatory paths in cells
• Contributes to metabolic stress
o Carbs:
• Lack of fiber -> increased energy density & decreased nutrients
39
Example of anti-inflammatory dietary pattern
Mediterranean & DASH diets:
- Increased: Fruit, veg, whole grains, fish
- Moderate: Alcohol, olive oil, chicken, legumes
- Decreased: Red meat, high fat dairy products, refined grains, salt, added sugar
- -1 < IS < 0
