Thursday, January 31, 2008

Cancer, fiber and the PPT

I've lost a study. It's really annoying when that happens, you flick through a patient characteristics table and think, hmmmm, I'll keep that. Then you don't. This was another colorectal cancer and/or polyp study. Probably looking at fiber. It was another of those splits, people who got cancer vs those who didn't. I was reading the baseline patient characteristics. The eye catching parameter was financial income. Below so many thousand dollars (possibly Aussie dollars) of income per year was bad news for colorectal cancer. Higher income improved prognosis. Sorry, higher income was "associated" with a better prognosis.

Another of those missed opportunities to try throwing money at a problem.

While I was hunting said paper I hit on the PPT (Polyp Prevention Trial). This was another mega intervention trial along the lines of WHEL in breast cancer. I had the temerity to click on the "related articles" link and all of the papers poured out. Significant increases in all of the politically correct stuff, sustained with INCREASING compliance over 4 years. Fat was down at close to 20% of calories with at least 7 servings of plants a day. Enough fiber you wouldn't want to share an enclosed space with an intervention participant for too long. Obviously produced diddly squat improvement compared to no intervention by four years, so they followed for eight years. You can't say that this belief structure doesn't engender persistance! More diddly squat at eight years.

However people in the intervention group felt very positive about the whole thing. That's nice. But nobody seemed to care about the control group...

Overall, not a lot to show for eight years of work. But of course it needed doing to disprove the hypothesis that fruit 'n' fiber is good for you, which it did, nicely. No one seems to have been overjoyed. Or noticed for that matter.

Somewhat hysterically they did a data trawl and came up with this gem.

Again, please be cautious about getting in to a lift with someone eating enough dry beans to make a difference. If it really was beans which made the difference, which I doubt.

Peter

6 comments:

Erik said...

Dry beans? That seems a little far fetched! I can almost feel their desperation to come up with something after eight years of study ... Thanks for the blog, keep up the good work. //Erik PS. Please allow OpenID-based accounts to comment to your blog also ...

mtflight said...

Great stuff, Peter.

Martin said...

For the past eighteen months I have been eating nothing but nuts, eggs, fish and meat. I've never felt better in my life. I avidly read your blog and the blogs of several other L/C advocates. All tremendous resources. I have never seen a blog post or a comment about the effects of this diet on fecal elimination. For me, the change in diet from fairly large amounts of fruit and vegetables to virtually none, has had a large effect; it's, perhaps, the most beneficial change of my entire life. Without the fiber the whole process is vastly easier. I travel a lot, and as I believe many people experience, regularity is difficult to maintain on the road, and especially when crossing multiple time zones. With the change in diet, I never have a problem. No bloating or constipation. No discomfort at all, and when the time comes the difference is night and day from the difficulties, that at least for me, always seemed to arise from a high fiber (and high sugar) diet. It seems a much more natural process now. Far easier that's for sure. I am just wondering if this is a common experience on a very low carb diet? Is the whole fiber thing another mainstream myth?

Thanks for the work you're doing on the blog.

Day

Peter said...

Hi Day,

Yes the whole fibre thing is a complete mainstream myth. It was set up to save the lipid hypothesis indirectly. Obviously if fat was bad then carbs had to be good (you've got to eat something!), but carbs were clearly bad per se. Fibre was the missing ingredient to explain the paradox of low fat/high carb diets being bad for you. Wrong again!

Peter

Ace said...

My GI doc swears that high-fat diets are bad for the colon, and that high-fiber is good.

I understand how the pro-high-fiber thinking happened, but do you have any idea how they got stuck on the high-fat phobia?

Peter said...

Hi Ace,

Yes, that's a normal GI specialists view, and s/he is very welcome to it. My problems is whether you gastroenterologist has actually read the PPT. If not then, shrug maybe they should read it, if so, how do you square that circle?

In general high fat is a combination of semantics, ie your GI specialist's high fat diet is essentially a cafeteria diet high in fat and sucrose. Substitute ketogenic for high fat and there are no observatiional studies because there are no ketogenic populations to observe (thank you AHA) and lab models of ketogenic diets ususally show them to be protective unless you base them on omega 6 oils.

Never forget that your cardiologist believes, totally, that LDL cholesterol causes arteriosclerosis. Shrug!

Peter