in defence of carbohydrates……...0.9kg greater weight loss at 1 year 2.0kg greater weight loss in...
TRANSCRIPT
In defence of Carbohydrates……
Catherine CollinsRD FBDA
To eat carbohydrate is to eat plants
the original ‘plant based eating’ concept
The “good”
The “bad” The “ugli”
Starches +InsolubleFibre:‘roughage’
Starches +Soluble Fibre:‘prebiotic’
(Polyols)
ModifiedStarchesdextrins
Di-saccharideslactosesucrosemaltose
Mono-saccharidesfructoseglucoseribose
Complex carbohydrates to simple sugars
‘Glycaemic carbohydrates’
Starches‘complex carbs’
but….
“this classification does not allow a simple translation into nutritional effects since each class of carbohydrates has overlapping physiological properties and effects on health”
“Carbohydrates can also be classified according to their digestion and absorption in the human small intestine”
• Digestible carbohydrates are absorbed and digested in the small intestine
• Nondigestible carbohydrates … reach the large intestine where they are at least partially fermented by the commensal bacteria present in the colon
“There is no universal definition of the term dietary fibre”
SACN, 2015
Polysaccharide: Dextrin
Disaccharide: Sucrose(glucose + fructose)
Mono-saccharide: Fructose
(3-20 glucose units)
Carbohydrates: a product of shape
Starches + InsolubleFibre: ‘roughage’
Starches + Soluble Fibre: ‘prebiotic’
Amylopectin(can contain up to 2 million glucose units)
Cellulose
Starches‘complex carbs’
Beta-glucan(also FOS, GOS)
Carbohydrates: a product of shape
digestion
absorption
Blood glucose measurement
Sucrose
Starch
All digestible carbs become ‘simple’ sugars at point of absorption into bloodstream
The effect of carbs on blood sugar depend on the: • amount consumed• viscosity of food(s) eaten• relative amount of protein or fat eaten at same time• ability to absorb sugars readily
Better blood glucose control
viscosity
fermentability
Uptake of glucose slowed 20% over 2h post-meal
Improved post-meal glucose control, particularly in T2DM
Improvement in insulinaemia in non-diabetes
Support bowel bacteria Fermentation produces short chain fatty acids Boosts muscle glucose uptake
Lowers bowel pH
Beta-glucan
Lowers total and LDL ‘bad’ cholesterol
El Khoury D et al. J Nutr Metab 2012;2012:851362
The more wholegrains, the better the reduction
19% reduction in coronary heart disease risk per 90g wholegrain carb
Aune D et al. BMJ 2016; 353:i2716
Wholegrain carb consumption:Systematic review and meta-analysis
17% reduction in mortality per 90g wholegrain carb
The more wholegrains, the better the reduction
Aune D et al. BMJ 2016; 353:i2716
Wholegrain carb consumption:Systematic review and meta-analysis
Carbs and ‘GI upset’…
Fructo-oligosaccharides
Galacto-oligosaccharides
Lactose
Sorbitol
Mannitol
Fructose
Beta-glucan
‘threshold’ effect of single or combination FODMAPs
Carbs lend themselves to ‘portion distortion’:
“Reduced portion size has the highest potential to reduce the population health burden of obesity”.
Dobbs R, Sawers C, Thompson F, et al. Overcoming obesity: an initial economic analysis. McKinsey Global Institute, 2014.
The ‘Mastermind’ approach…
“I’ve started so I’ll finish”
Systematic review, WHO sponsored data: sugar and weight
Meta-analysis of 11 trials
Duration 4 weeks to 6 months
Iso-energetic exchanges of
free sugars with other
carbohydrates:
No change in body weight
(0.04 kg; 95% CI: –0.04, 0.13)
Reduced sugar intake
Increased sugar intake
Sugar replaces other foods
(iso-energetic)
Meta-analysis of 5 trials in
adults with ad lib diets:
Duration 10 weeks to 8 months
Sugar intake reduced 48 – 77g
per day
in body weight of –0.80 kg
(95%CI:–1.21, – 0.39)
Meta-analysis of 10 trials
Duration 2-6 months
40-400g additional
carbohydrate each day,
mainly as sugar-
sweetened beverages
↑ in body weight 0.75 kg
(95% CI: 0.30, 1.19)
Te Morenga L et al. BMJ 2012; 346:e7492
0.9kg greater weight loss at 1 year
2.0kg greater weight loss in those following stricter low carb diets
Meta-analysis: diet and metabolic risk factors
Better results than low fat diets
23 studies 2788 participants 6-24 month study duration
Both diets equally effective at: body weight waist circumference blood pressure total to HDL cholesterol ratios total cholesterol LDL ‘bad’ cholesterol triglycerides blood glucose serum insulin levels HDL ‘good’ cholesterol
Low carb diet<45% kcals
n=1362
Low fat diet<30% kcals
n=1396
Better results than low carb diets
Hu, T et al. Am J Epidemiol 2012; 176: S44-S54
Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet
Low-Fat Diet n=104
• Low-fat, restricted-calorie diet
• based on American Heart Association guidelines
• 1500 -1800 kcal per day
• 30% of calories from fat
• 10% of calories from saturated fat
• 300 mg of cholesterol per day.
• recommended low-fat grains, vegetables, fruits, and legumes
• Limit fats, sweets, and high-fat snacks intake
Mediterranean Diet n=109
• Moderate-fat, restricted-calorie diet
• based on the recommendations of Willett and Skerrett
• 1500 -1800 kcal per day
• goal <35% of calories from fat
• added fat were 30-45 g of olive oil and a handful of nuts <20 g) per day
• rich in vegetables
• low in red meat -poultry and fish replaced beef and lamb
Low-Carbohydrate Diet n=109
• Low-carb, non–restricted-calorie diet
• based on the Atkins diet
• calories, protein and fat intake not limited
• 20 g of carbohydrates per day for 2-month induction phase and immediately after religious holidays
• gradual increase to a maximum of 120 g per day to maintain the weight loss
• participants counselled to choose vegetarian sources of fat and protein and avoid trans fat
Shai I et al. NEJM 2008: 359:229-241
Weight change over 2 years; 3 diet styles
−2.9 ± 4.2 kg for the low-fat group
−4.4 ± 6.0 kg for the Medit-diet group
−4.7 ± 6.5 kg for the low-carb group
Shai I et al. NEJM 2008: 359:229-241
Low carb vs iso-energetic diets for weight loss and cardiovascular risk
Naude CE, et al. PLOS ONE 2014; 9(7): e100652
Naude CE, et al. PLOS ONE 2014; 9(7): e100652
Low carbohydrate versus balanced diets for weight loss (kg) at 3–6 months:overweight and obese adults with type 2 diabetes
Naude CE, et al. PLOS ONE 2014; 9(7): e100652
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Low carbohydrate versus balanced diets for weight loss (kg) at 3–6 months: overweight and obese adults
Naude CE, et al. PLOS ONE 2014; 9(7): e100652
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0.62 kg more lost in low carb group
0.75 kg more lost in low carb group
Pro
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Low carb diets and mortality
17 cohort studies; 9 selected
“Our systematic review and meta-analyses suggest low-carbohydrate diets associated with a significantly higher risk of all-cause mortality”
“low-carbohydrate diets might not be protective or harmful in terms of CVD mortality and incidence”
“These findings support the hypothesis that short-term benefits of low-carbohydrate diets for weight loss are potentially irrelevant”
Noto H et al. PlosONE 2013:8(1): e55030
• Neither beneficial nor harmful to human health
• High sugar consumption associated with incidence of dental caries
• No association between total carbs or type of carbs and incidence of Type 2 diabetes
• Association of T2DM with white rice in China and Japan, but amount eaten is far higher than UK population
• Strong evidence that cereal fibre and wholegrains lower cardiometabolic disease and colorectal cancer incidence.
• Claim that diets higher in total carbohydrate cause weight gain not supported by evidence
Carbohydrates: our major energy source
SACN, 2015
What’s the alternative?
Carbs45%
Protein20%
Alcohol5%
Fat30%
RECOMMENDED
Carbs15%
Protein30%
Alcohol5%
Fat50%
LOW CARB
Carbs Protein Alcohol Fat
Carbohydrate recommendations…
Per 2000kcal diet90% 100%80%70%60%50%40%30%20%10%0%
450g 500g400g350g300g250g200g150g100g50g0g
Very low carb ketogenic diet (VLCKD)
Low carb dietModerate carb diet
High carb diet
Equivalent as carbohydrate
How do we inform public of carbohydrate requirements?
1. Consider total calories, then recommend carb as a proportion of them; does not specify carb source
2. Use ‘modelling’ to calculate the type and amount of carb-rich foods needed for health
Carbohydrate recommendations…
Per 2000kcal diet90% 100%80%70%60%50%40%30%20%10%0%
450g 500g400g350g300g250g200g150g100g50g0g
Low Moderate High
Eatwell Guide; Public Health England 2016
Equivalent as carbohydrate
130-260g ‘Lower carb’ diabetes diets such as X-PERT
130g/d for brain (IoM, 2005; EFSA NDA Panel, 2010, SACN 2015)
Ketogenic diet – induces ketones to treat intractable epilepsy
Carbohydrate recommendations…
Per 2000kcal diet90% 100%80%70%60%50%40%30%20%10%0%
450g 500g400g350g300g250g200g150g100g50g0g
American Heart Association guidelines
Eatwell Canada; 2011
Eat for Health, Australian Dietary Guidelines; 2013
Dietary guidelines for Indians; India 2011
Ministry of Health, Brazil; 2014 ‘from cereals and roots’
WHO/FAO report; 2003
Eatwell Guide; Public Health England 2016
Equivalent as carbohydrate
‘Lower carb’ diabetes diets
Low Moderate High
‘Modelling’ applied to Eatwell Guide
• To meet all DRVs for micro- and macronutrients
• Meet the SACN 2015 recommendations for 30g fibre
• Meet the minimum 5-a-day fruit and vegetable goals
• Include at least 2 portions of fish per week, of which one oily
• 70g or less of red or processed meat daily
starchy carbs 69%
Fruit/ veg71%
Dairy / similar-29%
Foods high in fat and sugar -53%
Meat/ pulses-24%
0 change
The Eatwell Guide; Public Health England 2016
St Kitts & Nevisand
Finland healthy eating
guides
Carb rich, low energy dense
Carb rich, energy dense
“Eat for Health”Australian Dietary Guidelines 2015
www.eatforhealth.gov.au
• Photographic approach, some naming
• Smaller carb section – recommend 4-6 portions a day
• Similar fruit and veg- but divides group
• Oils and spreads kept ‘off model’
• Alcohol and fast food feature
Australian guidelines: carb portions
www.eatforhealth.gov.auModified graphic excludes milk and yoghurt recs as carb containing foods
Without Carbohydrates……An Indian meal would be paneer and chicken tikka
Without Carbohydrates……
Fish and chips would be sushi
Without Carbohydrates……
Spaghetti Bolognese would be mince and cheese
Future carbs….
• Alliance with pulse protein for healthier plant based snacking
• Promote environmental credentials
• Portion-ready: single wrapped, or pack indication of portions
• Wholesome fibre ‘boosts’ for the friendly microbiome !
• Blend veg and grains for calorie-controlled dishes
• Novelty substitutes, not ‘hidden’ ones
• Let’s focus on the fermented, instead
Even Paleo man ate carbs…
Hunter-gatherers avoidance of dietary protein intake >40% energy to minimise metabolic toxicity
Digestive system able to break down complex carbs into sugars for absorption
Concentrated starch from plant food essential to meet metabolic demand of an enlarged brain
Two forms of digestive enzyme amylase – one in saliva, one produced by the pancreas - to digest carb became advantageous when cooking became widespread
Reduction in tooth size as cooking solubilises starches
Gut microbiome harvests undigested carbohydrates to synthesis nutrients, maintain gut milieu, support immune function
In defence of carbs….
“LCHF diets are defined by what is ‘not’ eaten, instead of what is eaten”
Tim Noakes
“Food is an important part of a balanced diet”
Fran Lebowitz