Comments on: What’s more important – glycaemic load or fructose?

By: Bill Shrapnel

Bill Shrapnel — Wed, 10 Sep 2014 21:07:37 +0000

Hi Denis
Fructose is metabolised in the liver. The key question is: what is fructose metabolised to?
In pop nutrition circles we often here that ‘fructose turns to fat’ i.e. that fructose is converted to free fatty acids in the liver, contributing to fatty liver and high blood triglycerides. This can happen but it doesn’t happen very much – it appears that only 1-5% of dietary fructose has this fate. Most of the fructose we eat is converted to something else.
About 25% of fructose is converted to lactate, but by far the majority of fructose (about two-thirds) is converted to glucose. Most of this appears in the bloodstream in the six hours following consumption of fructose; some is stored as glycogen.
So the mantra should be ‘fructose turns to glucose’, not fat.
If you would like to read about this from a world expert I would recommend you look at the work of Professor Luc Tappy (http://physrev.physiology.org/content/90/1/23.long).
Regards, Bill

By: Denis

Denis — Wed, 10 Sep 2014 11:56:28 +0000

Bill, I’m curious. Where is Fructose metabolised if not in the liver? Any information I’ve found on the topic states that fructose is almost totally metabolised by the liver.

By: Jenny

Jenny — Wed, 13 Aug 2014 10:35:56 +0000

There is no way I would even consider going that high! Low carb stabilises me and keeps me off the blood sugar rollercoaster!

By: enw

enw — Wed, 13 Aug 2014 00:23:59 +0000

It all depends on what is replacing the carbohydrate when it is this restricted (<45%), often this is fat.

So for long term health benefits,the fat needs to be less saturated more poly/mono, and omega 3. We know in the short term carbohydrate restricted diets <45% may improve glycemic control but not blood lipids, so what happens in the long term is an area of interest. Also it is more challenging to get sufficient vitamins, minerals and fibre especially soluble fibre on such a restricted diet required for other areas of health for example gut health, often seen in those with coeliac disease.

However is it really necessary to restrict this low when good BGL control and better blood lipids can be achieved with carbs up to 60% of energy , as part of mixed meals, of good nutritional value and low GI. There are many fit healthy individuals with diets having carbohydrates that are at this level with and without diabetes who have a healthy body weight, but of course for long term health this needs to be of good nutritional value, lower GI and part of mixed meals, remain active and maintain a healthy body weight. I think the range 45-65% carbs/energy is entirely reasonable to meet many different lifestyle and nutritional needs.An individual approach is required in the end.
Nutritional guidelines are for all groups of people not just the 60% who are inactive and overweight or at risk of being overweight and developing lifestyle diseases which I understand is the main focus of your article.

By: Jenny

Jenny — Tue, 12 Aug 2014 13:57:28 +0000

I’ve tracked mine and I do fine hovering around 20%!

By: Bill Shrapnel

Bill Shrapnel — Tue, 12 Aug 2014 03:34:09 +0000

I actually think that carbohydrate intakes below the range of 45-65% are quite OK, provided the quality of the carbohydrate-rich foods in the diet is good. In particular, nutrient-rich carbohydrate foods should be emphasised if overall intake of carbohydrate is low, just to ensure that the diet has enough of the micronutrients carried by carbohydrate-rich foods.
I get a bit nervous recommending healthy diets with up to 65% of calories coming from carbohydrate. You can do it but, again, carbohydrate quality needs to be high. And this time the emphasis needs to be on high fibre and low glycaemic index foods, which sits comfortably with the idea of eating whole foods or ‘real’ foods.
Overall, the total amount of carbohydrate in the diet doesn’t matter that much – it’s the quality that counts. Regards, Bill

By: Bill Shrapnel

Bill Shrapnel — Tue, 12 Aug 2014 03:22:18 +0000

Hi Sean. Findings that both sugar-sweetened soft drinks and non-sugar soft drinks are associated with risk crop up several times in the literature.
Did you see this study in the three Harvard cohorts in relation to soft drinks and hypertension? http://www.ncbi.nlm.nih.gov/pubmed/22539069
As both types of drinks are associated with hypertension it’s had to argue that fructose or sugar is driving the problem. And it seems unlikely that some other aspect of these drinks is the cause, though it’s not impossible. Alternatively, it may just be due to confounding. We do need to be mindful of the shortcomings of observational studies. Regards, Bill

By: enw

enw — Tue, 12 Aug 2014 02:05:52 +0000

Great work for changing your diet and improving your health status. There is nothing better than being healthy!
Cutting all the [rubbish] out of your diet certainly improves the quality of the diet. However people forget that they get carbohydrate from a wide variety of foods not those we traditionally associated with carbohydrate.
Depending on your interpretation of the Paleo diet, which is so diverse these days on what is excluded or included and generally not that strict as in the traditional times but ” Eating Real Food’, carbohydrate can come from other cereal grains slightly less processed like quinoa, amaranth etc , so many vegetables but often more associated to the starchy vegetables like peas, parsnips, corn and pumpkin to mention a few , legumes, and lentils if these are included, milk/yoghurt , nuts, seeds and whole fruit if any of these foods are regularly into the diet. And when this is all added up the carbohydrate content in your diet is not always that low but fits well within the 45-65% of energy eaten, which is recommended for health especially those with T2 diabetes. It’ s just now coming from more whole than processed foods in a diet which I imagine the energy intake has been significantly reduced because of the more bulky foods eaten. And this lower energy and possibly weight loss has the most impact on metabolic syndrome, reducing your processed carbohydrate in your diet helped you achieve this..

By: Sean

Sean — Tue, 12 Aug 2014 02:02:52 +0000

Thanks for the insight Bill. I too now wonder if soft drink consumption could be a marker of other behaviours related to diabetes risk, or if there is potentially a causal link with non-sugar sweetened beverages.

By: Bill Shrapnel

Bill Shrapnel — Mon, 11 Aug 2014 20:46:20 +0000

Hi Shane. The anti-fructose thing seems to be based on (1) studies in which vast amounts of fructose have been fed (25% of calories), (2) overfeeding with fructose (where the overfeeding is actually the major problem) and (3) the misconception that all fructose consumed is immediately metabolised to fat in the liver – it isn’t.
I spoke to a fellow recently whose wife had just recommenced eating fruit after nine months on a strict no-sugars diet. Apparently she had started to feel quite unwell.
How do we encourage moderation in a time when dietary extremes are pushed so hard by people who haven’t really got a clue what they are talking about? Regards, Bill