Week 4(2) - Carbohydrate, fat and health Flashcards
Disability adjusted life years (DALY)
Estimates how diseases burden the life of the population - number of years lost to any disability
DALY is measured by combined: YLD and YLL
Total dietary intake effect on DALY:
Total dietary intake is the 4th highest contributor to disability adjusted life years in males and the 3rd highest contributor in females
Inequalities in diets contribute to overall inequalities in health:
- Females living in the most deprived areas were expected to live less than two-thirds of their lives in good general health (Healthy life expectancy at birth. England 2018-2020)
- In England those born in the most deprived areas would expect 60 years of good health and 26 years in poor health while those in the least deprived areas (wealthiest) are expected to live 71 years in good health and 16 years in poor health
Observational studies:
Studies don’t involve treating or interventions – looks at existing dietary behaviours in a cohort e.g., looking at the Mediterranean diet via self-reported intake.
Will find association but can’t establish causation due to potential confounding factors and variables
Intervention studies
Intervention group vs control group – can give evidence of cause and effect
Systematic reviews and meta-analyses:
- Systematic reviews and meta-analyses of observational studies and randomised controlled trials conducted to summarise existing evidence.
- Findings from different levels of research are integrated and translated into guidelines and recommendations
SACN total carbohydrate recommendation:
- Dietary reference value for carbohydrates: maintained at a population average of ~ 50% of total dietary EI.
- Total carbohydrate intake appears to be neither detrimental nor beneficial to cardiometabolic health, colorectal health and oral health.
- The type of carbohydrate does matter for health outcomes
Free Sugars
- A CHO that was found to be detrimental to health
- All sugars (monosaccharaides and disaccharides) added to foods and beverages by the manufacturer, cook or consumer
- Sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates
- Free sugars are not contained in the cell wall of the foods
What sugars don’t count as free sugars?
- Lactose (milk sugars) when naturally present in milk and milk products
- Sugars contained within the cellular structure of foods (e.g., whole fruit and veg)
SACN report: Sugars and sugar-sweetened beverages:
- Higher consumption of sugars and sugar-containing foods and SSBs* associated with a increased risk of dental caries or tooth decay
- Greater consumption of SSBs* associated with increased risk of type 2 diabetes.
- = Includes non-diet carbonated drinks, coffee/tea containing sugar, squash, juice drinks, sport drinks, energy drinks.
RCTs conducted in children and adolescents indicate that: consumption of SSBs results in greater weight gain and increases in BMI when compared to the consumption non-calorically sweetened beverages
SACN recommendation for free sugars:
- Average intake of free sugars should not exceed 5% total dietary energy intake from the age of 2 years +
- Consumption of sugars-sweetened drinks should be minimised in children and adults
Population intake of free sugars (UK):
- All age groups still exceed the maximum recommendation of 5% of total energy intake from free sugars
- Maximum intake (g/day) from age 11-75years should be 30g. Mean averages for 19-64year olds = 49.7g
Main UK diet sugar intake = sugary drinks, cereal products, table sugar, fruit juice
Cost savings of achieving the reduction to 5% EI from free sugars:
- If the SACN recommendations to reduce sugar innate to 5% of energy intake are achieved within 10 year, the cost savings to the NHS is estimated to be ~500M per annum by year 10
Strategies introduced to help reduce sugar intake:
- Sugar tax
Suggested strategies: - Mandatory sugar reductions in foods
- Stricter advertising
- Limit price promotions on sugary products in supermarkets
SACN dietary fibre recommendations:
Recommended an increase in the populations fibre intake to an average of 30g per day for adults
* For children the recommended intakes are: 15g/day (2-5 years), 20g/day (5-11 years) , 25g/day (11- 16 years) , 30g/day (16-18 years).
Why do we need to increase fibre intake?
- Diets rich in fibre (particularly cereal fibre and wholegrains) are associated with lower incidence of CVD, type 2 diabetes and colorectal cancer.
- Diets rich in fibre reduces intestinal transit times and increases faecal mass (reduce constipation). All signs of a healthy gu
RCTs findings on fibre:
- Higher intake of oat bran and isolated β-glucans (soluble fibre found in porridge oats) leads to lower total cholesterol, LDL-cholesterol and triacylglycerol concentrations and lower blood pressure (CVD risk factors)
- LDL cholesterol contributes to the formation of arterial plaque – the process of atherosclerosis (a major CVD risk factor
Population intake of dietary fibre (UK)
From 16 years+ the recommended intake = 30g/day
All age groups fail to meet the recommendation for fibre intake
The mean intake for adults was: 19.7g/day
Structure of fats:
- ~95% of dietary fats is comprised of triglycerides – these are composed of a glycerol backbone and 3 esterified FAs
- FAs are characterised based on the number of double bonds they have
- Unsaturated fats contain 1 or more double bond
- Polyunsaturated fat contains more than 1 double bond e.g., Veg oil, omega-3 FAs (fish oil)
- Saturated fat: contains no double bonds in its structure e.g., butter
- Monounsaturated FAs have 1 double bond e.g., olive oil and plant sources
what 2 key things does the structure of FAs determine:
1) Their health effects e.g., impact on cholesterol levels
2) Their melting point (whether they are solid or liquid at room temp)
Veg/ plant oils:
- Liquid at room temperature
- Olive oil is rich in monounsaturated fats, but does contain some saturated fats
- Predominantly rich in unsaturated fatty acids (but contain some saturated fatty acids)
Animal fats:
- Solid at room temp
- Predominantly rich in long chain SFAs
- E.g., butter is predominantly rich is saturated fats, but does have a small proportion of monounsaturated fat as well
UK SACN report (2015): saturated fats and health:
- The evidence indicated that reducing dietary intake of saturated fats:
reduces risk of CVD and CHD events
lowers total and LDL cholesterol
improves indicators of glycaemic control.
The population average contribution of SFA to dietary energy should be reduced to no more than ~10% (applies to adults and children 5 years and over)
* Recommendation suggests SFAs should be substituted with unsaturated fats
Saturated fat intake:
Globally we are exceeding SFA intake recommendations
The majority of SFAs in our diet comes from: milk and milk products, meat and meat products, and cereal and cereal products
For adults: 11.9% of total energy comes from SFAs
Isocaloric replacement of saturated with unsaturated fat associated with lower risk of CHD:
- Replacing 5% energy from SFA with either PUFA, MUFA, or carbohydrates from whole grains was associated with lower risk of CHD
- PUFAs came from marine and plant sources
- The type of CHO was important – replacing saturated fats with refined or added sugar did not lower risk of coronary heart disease
The randomised, controlled Dietary intervention and VAScular function (DIVAS) study:
- Replacement of SFAs with either MUFAs or n–6 PUFAs: lowered fasting serum total cholesterol (−8.4% and −9.2%, respectively) and low-density lipoprotein cholesterol (−11.3% and −13.6%). Replacement beneficially affected cholesterol profile.
- Authors estimated that these changes in LDL cholesterol concertation corresponded to an estimated 17-20% reduction in CVD mortality
- Shows that replacing saturated fats in our diets with unsaturated fats is a promising public health strategy for CVD risk reduction
