Dietary recommendations

Question 1

Describe the hierarchy of evidence

Answer 1

Meta-analyses 
SLR 
Critically-appraised topics 
Critically-appraised articles
RCTs
Cohort studies

Question 2

What are the 3 issues with using RCTs for nutritional recommendations?

Answer 2

1) Specificity: RCTs usually have a very specific intervention
2) time scale: RCTs usually don’t take int account duration of the exposure
3) Generalisation: translation of RCTs to the general population is usually quite problematic as a very specific cohort

Question 3

Dietary reference values: purpose, how they are formed, what the issues are

Answer 3

• DRVs are formulated for POPULATIONs to prevent deficiencies and malnutrition and typically are 2SD above the EAR
• Protein studies come from N-balance studies
• vitamin/mineral amounts come from theoretical calculations, repletion studies, urinary excretion, estimation of total body pool
• issues: do not consider disease prevention, not useful for individuals as it does not say anything about their micronutrient levels knowing their intake (they may need much less than the DRV!)

Question 4

Dietary reference values: what are the common deficiencies in the UK?

Answer 4

• iron: most common deficiency and found in 24-46% of people
• vitamin D deficiency in 12% of white people and up to 54% of South Asian people

Question 5

Dietary goals: purpose, how they are devised

Answer 5

• purpose: macro targets for optimum health and to prevent non-communicable diseases. Can be used to assess adherence to guidelines
• Evidence comes from epidemiological, observational, prospective and cohort studies

Question 6

Dietary goals: current macro recommendations

Answer 6

FAT: <35% (we are currently only meeting this target)
SF: <10%
PUFA: 6.5%
MUFA: 13% 
CHO: 50% 
Sugar: <5%
Fibre: 30g/day 
Salt: <6g/day

Question 7

Dietary guidelines: purpose, how they are formulated (3 aspects)

Answer 7

• purpose: to provide dietary advice for optimum health and to prevent NCD
• Formulated from:
  1) Non-linear programming: Taking into account government recommendations and what the public currently eat like, for more realistic recommendations
  2) Consumer research: Interviewing lay people and finding out that labelling is important and pictures are good for understanding
  3) Sustainability assessment: The Carbon Trust assessed the EatWell plate and found that it had fewer carbon emissions associated than the current average diet

Question 8

Dietary guidelines: how the old EatWell guidelines have been updated

Answer 8

• Now do not have high sugar and fat food included on the plate
• got rid of the knife and fork