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

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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