Monday, December 17, 2007

Who pays the piper.

This study, available in full text for free, makes some very interesting reading.

It compares the end results of two diets of identical macronutrient ratios, but differing sucrose contents, on insulin sensitivity. The subjects were moderately insulin resistant, slightly heavy volunteers. Result: Obtaining 25% of your calories from sucrose, compared to 10%, has absolutely no adverse effect on your insulin sensitivity. That's s relief to any sugar dependent young white male on the verge of type 2 diabetes. Or any researcher who's funding comes from here:

" This study was supported by an unrestricted research grant from The Sugar Bureau and Suikerstichting, the Netherlands".

But the study is very strange. It only compared the end results of the two diets. Neither diet was the volunteers' habitual diet. There was no formal comparison of the effect of the two new diets on the initial baseline parameters of health in the study participants. Oddly enough some of the changes do get mentioned in the discussion, others don't, on a rather random basis. The excess rise in LDL cholesterol (for anyone who cares) in the 25% sucrose diet compared to the 10% sucrose diet gets attributed to the higher saturated fat content of the high sucrose diet. What sort of dietician fails to control for this variable in a study reporting cholesterol levels? No need to answer that. And why not attribute it to the sucrose?

But you can look at a small number of the baseline data, selected by Dr Black and co, although not all of what was certainly measured.

So if you got to Table 2 of the results, on page 3568, line 8, you can see the fasting plasma glucose was 4.8mmol/l. Normal.

After 6 weeks on the dietician designed diet what was the fasting blood glucose? This never gets a mention anywhere in the paper. But it's there, tucked away in a table in the discussion of all places. Look at Table 7, page 3570, third variable reported.

Ooooooh, it's 5.6mmol/l. Whichever diet you look at.

A fasting plasma glucose of 4.8mmol/l for a carboholic is normal. A value of 5.6mmol/l is prediabetic.

How do you convert a slightly chunky healthy young Irish chap in to a prediabetic?

Easy, get a university nutritionist to design his diet.

Those freeliving chaps were eating 45% of calories as carbohydrate and 35% as fat before the study. Just increase the carbohydrate to 55% of calories and reduce the fat to 33% and voila, prediabetes in 6 weeks. Irrespective of sucrose content.

But don't mention this anywhere in the paper.

Why not? Re check who funded the study.

The purpose of the study was to show sucrose is harmless. It was not designed to look at the effect of carbohydrate in general on fasting blood glucose. It did that by accident.

Sometimes the truth just slips in and no one notices. Or they're not saying.

Enough of this depressing study. A much better one for the next post.



James said...

Not entirely related to this post but don't see an email link for you -- been reading your blog for a few days now (found via Seth Roberts' blog) and find it quite fascinating. I'm currently training for a marathon which involves drinking an awful lot of sports drinks, carb-loaded goo, etc. Do you have any thoughts on athletic performance on a high-fat diet?

Peter said...

Hi james,

It's a no no in the short term. My own impression is that my (non competitive) cycling took about a year to adapt. Kayak surfing, where the effort is maximal for either a few seconds to catch a wave or just extreme for a few minutes to get back out through the break, recovered a bit quicker. There really is an adaption period. Currently I only really exercise short term to maintain a reasonable muscle mass, pushbike hill climbs usually, as I now live inland. Surfing was more of an adrenalin rush which involved exercise rather than exercise per se...

Before I moved inland I sold my sea touring kayak to a guy who was doing a lot of carb loading before hard endurance cycling. He bought the boat despite not being able to fit in, as we got chatting about LC and weight. He was a big guy, over six foot and solid. I also lent him Barry Groves' book. He was in the boat within a couple of months, returned the book and is still LC eating generally, but I think with some mild carb loading before his endurance cycling.

There is this interview with Stephen Phinney

as an opinion piece which suggests that when you are truly LC adapted, endurance is excellent. That's very true but I'm not sure this would include winning a hill top sprint in a Tour de France mountain stage, though it just might...

Also from Nutrition and Metabolism:

suggests it can be done. Not in a few weeks though.

It's a long time since I was a serious athlete but I think you may to accept some personal damage if you are really going to get success at the extremes. Pheidippides didn't do too well health wise, but that certainly didn't worry me as a teenager!


Helen said...

Hey Peter,

Interesting stuff! I'm a dietitian and have spotted this exact pattern in a number of clients, so I risk the wrath of my profession by doing modified carb approaches with a number of my clients.
I've got a feeling that we will eventually end up with a "nutrigenomics" system, where your healthy might be 80% energy from animal fats and mine is somewhat different. I've also got a feeling gluten intolerance fits in here somewhere - if you want some papers...
Just hope we don't kill too many people off with bad advice in the mean time

Peter said...

Hi Helen,

While I am a pretty radical dyed in the wool LC eater, I have to admit that I really do not believe that this is necessary for everyone for health. I do think it may be the easiest route though. There are so many aspects to this that it is a post on its own. What I do believe is absolutely necessary is that people eat food. That means food as it was before mankind agriculturalised it. Until recently meat, dairy and eggs were pretty close to food. Few vegetables remain as food. "Junk" food certainly isn't. Grains aren't. But in Kitava humans are healthy on 70% of calories from sweet potatoes and yams...

The problem seems to be that those people who are most easily damaged by non-food really do get broken. Putting a type 2 diabetic on a LC diet will clearly save their eyes, toes and kidneys. But they're still broken.

I love gluten intolerance. Papers, yes please.

I'll put my email up for a day or so as the post after this one.

Thanks in advance.


PS Although I tend to be a bit (!!!!!!) down on what medics, dietitians and we vets do nutritionally, there is absolutely no doubt that there are individuals within our professions who really do think. Unfortunately they don't seem to be the ones who set the policies which produce such awful problems. Good luck with your forays in to modified carbs, choose your patients well...

Peter said...
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AJ said...

Hello Peter,

I've just started reading your hyperlipid blog and find it truly fascinating. I linked to it from PaNu, another favourite. This whole idea of high sat fat/low carb is amazing -- I am putting the ideas into practice and reaping the benefits more and more every day. My challenge is to turn my loved ones into believers too, but that is a slow process. Not everyone loves to dig into the subject as much as I do, so they remain skeptical and uninformed.

My main question relates to your profession as a vet. What can/should I do (diet-wise) to guarantee that my lovely 5 year-old chocolate lab is eating right, and staying as healthy as I am? After all, I am the one providing her food. (Is she trying to tell me something when she searches out and devours the animal excrement she finds on her walks?!) I would appreciate any suggestions you can give me.

Thank you for all your generous work. I am gobbling it up.

Aj Drakie

Peter said...

Hi AJ and thanks,

I'll comment tomorrow, bed time now!