June 7, 2011

News You Missed. WHI: Low Fat Diet Dramatically Worsens Diabetic Blood Sugars

Over the past month the media have been busy doing what they do best--reporting bady designed animal research as if it were human research. As a result we read "A high-fat diet during pregnancy may program a woman's baby for future diabetes, even if she herself is not obese or diabetic." This headline multiplied through the web appearing on dozens of newspaper sites.

Only by reading the full article do we learn that the researchers concluded this after an undisclosed, but probably low, number of "obesity-resistant rats" were "fed... either a high-fat or a control diet from the first day of gestation."

Rodents have evolved to eat a very different diet than humans and don't do well on high fat diets. They have very different pancreases and enzyme function than humans. And, of course, the "high fat diet" used in rat research is also a high carbohydrate diet. But that didn't deter the media from reporting this finding as if it were a human study.

Another study that was reported in the media claimed that "Pregnant women who tuck into fatty foods are at greater risk of having a stillbirth."

Further reading reveals that "The team studied two dozen pregnant Japanese macaque monkeys, an animal that has a placental structure similar to humans." Not mentioned here is the fact that Macaques, like other monkeys, have evolved to eat a very different diet from humans. They live mostly on fruits, herbs, and seeds, seasoned with the occasional insect, and can't tolerate the diet of fatty meat that humans evolved to not only tolerate but flourish on.

These are just a few of the animal research studies demonizing the impact of fat on females that appeared over the past month. But what about research that looked at the impact of fatty diets on female humans?

There was , it turns out, a blockbuster human study published this past month--an important study that described the impact of a low fat diet on real, live human women. Shockingly, it received no mention in the press at all.

But what a study it was! Unlike the studies that featured a dozen monkeys or a lab full of rats, this study tracked the outcomes for 2,263 human women, whose diet, blood sugar, and insulin were tracked for six full years.

And what it found was this: Low fat diets harm women with diabetes. Here's the study:

Effects of a low-fat dietary intervention on glucose, insulin, and insulin resistance in the Women's Health Initiative (WHI) Dietary Modification trial Shikany JM, et al. Am J Clin Nutr. 2011 May 11. [Epub ahead of print]

To understand how important a result this was, we need to back track a little and remind ourselves of what the largest and best designed study of the low fat diet has already proven, which is that in almost 49,000 middle aged women, tracked over eight years, the low fat diet was shown to have zero effect on preventing heart disease or stroke. None. Nada. Zip.

The earlier publication describing the WHI findings concluded
Over a mean of 8.1 years, a dietary intervention that reduced total fat intake and increased intakes of vegetables, fruits, and grains did not significantly reduce the risk of CHD, stroke, or CVD in postmenopausal women.
You can find the report from that study here:

Low-Fat Dietary Pattern and Risk of Cardiovascular Disease:The Women's Health Initiative Randomized Controlled Dietary Modification Trial
Barbara V. Howard et al. JAMAVol. 295 No. 6, February 8, 2006

When this result hit the press in 2006, the media and the high profile doctors who have been promoting the low fat diet for decades responded by asserting that the diet used in the study must not have been low enough in fat, or that the study hadn't lasted long enough to demonstrate the benefits that the low fat diet must have. No one was willing to admit that maybe the study had proven what it looked like it proved--that the low fat diet was a useless intervention.

Doctors continue to recommend low fat diets. Dietitians continue to warn people with diabetes about the dangers of eating fat.

But now, this lastest analysis of the WHI data shows just how wrong-headed they are, because what the researches did here is to take the further step of analyzing the results for the subset of women for whom they had blood sugar measurements at the start of the study.

What they found was that for women with diabetes, the low fat diet wasn't just useless, it was dangerous, because it raised their blood sugar significantly--and I don't mean just statistically significantly. I mean it raised it a lot.

In the study's words, "...diabetic women had an increase in glucose that was 7.9 ± 20.3 mg/dL greater in the DM [diabetes]-I[ntervention, i.e. low fat diet group] than in the DM-C[ontrol] group (P for interaction <0.001).

In short, women with diabetes who didn't eat a low fat diet ended up with much better blood sugars, even though both groups were eating a high carbohydrate diet!

Since these were diabetic women who were likely to be taking medications to lower their blood sugar, the rise in blood sugar seen on the low fat diet is worse than it looks, because it takes into account the higher doses of medications they were probably taking.

Science doesn't get any clearer than this. This is a huge, well designed study. It found that the low fat diet caused significant harm in people with diabetes by raising their blood sugars. The broader study already confirmed that the low fat diet didn't do squat to prevent heart disease in anyone who participated in the study.

Yet not a word about this study made it into any major newspaper. I only found this study thanks to an alert reader who posted the link in the comments section of the previous post.

Is this shameful? Yes. Typical. Yes. Tragic for the millions of people with diabetes who get their health information, such as it is, from mainstream media. You tell me . . .

 

14 comments:

O Primitivo said...

"(...) Asserting that the diet used in the study must not have been low enough in fat,"

Women's Health Initiative Study Group. Dietary adherence in the Women's Health Initiative Dietary Modification Trial. J Am Diet Assoc. 2004 Apr;104(4):654-8. http://www.ncbi.nlm.nih.gov/pubmed/15054353

This new WHI May/2011 diabetes study starts with this info: "Glycemic effects of the Women’s Health Initiative (WHI) low-fat dietary intervention are unknown."

So it took investigators 9 years to find the adverse glycemic effects of the low-fat diet on diabetes? Nutritional science moves at a really slow pace...

frankweir said...

But what in the low-fat diet worsened sugar control if both groups were eating high carb?? I looked at the abstracts but I'm not knowledgeable enough to parse it out. I sense that most readers and Jenny know so PLEASE let me know. Did the low fat/high carb diet force the diabetic group to eat more carbs versus what they would eat if on a high fat diet? That's all I can think of.

Jenny said...

Bingo. The low fat diet replaces calories from fats with carbohydrates. Fats also digest more slowly and give a feeling of satiety that carbohydrates don't give.

frankweir said...

Jenny....Thanks for your response! How can I send you a modest donation? Your blog and book have helped me tremendously with getting serious about my T2 condition. My A1c has gone from 7.5 in November to 5.8 a couple weeks ago. I'm very serious. How can I send you a donation to help with your mission??

Jenny said...

Frank, You are very kind to offer, but I'm very fortunate to have the means, and time, to do this and don't need contributions.

What I do encourage everyone who appreciates this site to do is to use what you learned here to reach out to other people who have diabetes but aren't the kind who seek out information on the web. Let your doctor know about the site, too, if they comment on how well you are doing.

lightcan said...

Hi Jenny,

can I say that my 68 yo mother who is diabetic for the last 27-8 years and who was on a low fat/low cal for ages (a diet that didn't help with the recent obesity - last 7 y) and on statins got colon cancer because of her poor glucose control and bad advice? Am I right, considering your evidence?

Jenny said...

Lightcan,

There are many other factors that can promote colon cancer including genes, smoking, drinking and bad luck a.k.a. things we don't know about. So it's tough to blame one factor.

The other issue is that poorly controlled blood sugars (i.e. that 7.0% A1c doctors recommend) weaken the immune system and the immune system is a huge part of how the body keeps cancers from growing into tumors.

But that said, I know several health nut types who ate only organic foods and were slim and well exercised who died of colon cancer young. So it's tough to assign blame.

Jenny said...

Lightcan,

There are many other factors that can promote colon cancer including genes, smoking, drinking and bad luck a.k.a. things we don't know about. So it's tough to blame one factor.

The other issue is that poorly controlled blood sugars (i.e. that 7.0% A1c doctors recommend) weaken the immune system and the immune system is a huge part of how the body keeps cancers from growing into tumors.

But that said, I know several health nut types who ate only organic foods and were slim and well exercised who died of colon cancer young. So it's tough to assign blame.

O Primitivo said...

“49,000 middle aged women, tracked over eight years, the low fat diet was shown to have zero effect on preventing heart disease or stroke.”

Not exactly for the postmenopausal women with a history of CVD. The WHI low-fat intervention increased major CHD (nonfatal MI or CHD death) by 24% in this sub-group. This is a well hidden fact in the WHI long list of failures. To calculate this number, please see the WHI CVD paper, page 661, table 4:

Howardet a. Low-fat dietary pattern and risk of cardiovascular disease: the Women's Health Initiative Randomized Controlled Dietary Modification Trial. JAMA. 2006 Feb 8;295(6):655-66. PubMed PMID: 16467234. http://jama.ama-assn.org/content/295/6/655.full.pdf

Table 4 has clinical outcomes for "All participants" and "Participants without history of CVD". By subtracting these two tables we can calculate the outcomes form "Participants with CVD". For example, in the case of Major CHD (nonfatal MI or CHD death):

All women (nControl = 29294; nInterv = 19541):
major CHD - nControl: 863; nInterv: 559

Without CVD (nControl = 27925; nInterv = 18633):
major CHD - nControl: 733; nInterv: 452

Subtract values one by one, to find these:

Women with history of CVD (nControl = 1369; nInterv = 908):
major CHD - nControl: 130; nInterv: 107

Now we can calculate the absolute risks of major CHD for women with history of CVD: Abs_risk_control = 130/1369 = 9.496 %
Abs_risk_interv = 107/908 = 11.784 %.

The relative risk is obtained by dividing the absolute risks in intervention and control:
Rel_risk_majorCHD_womenCVD = 11.784 / 9.496 = +24.1 %.

So, the WHI low-fat intervention increased major CHD (nonfatal MI or CHD death) by 24% in woman who had a history of CVD.

In his paper “Why the Low-Fat Diet is Stupid and Potentially Dangerous” (see http://bit.ly/k6pd8d ), Anthony Colpo says that “Among the 3.4 percent of trial participants with pre-existing cardiovascular disease, those randomized to the low-fat diet experienced a 26% increase in the relative risk of non-fatal and fatal CHD”.

Colpo says it was 26%, according to my calculations its “only” 24%.

Jenny said...

O Primitivo,

Thanks for the insightful analysis!

There's no arguing with religious beliefs, and sadly, beliefs about the effect of seem to be stored in the same part of the brain as the most irrational of religious beliefs and are defended against facts with the same rabid intensity.

I see this in aherents to every denomination of dietary choice: low fat, low carb, gluten-free, etc.

It must be something hardwired into the primate brain.

It's also why I try to keep the focus on what our meters tell us and stay out of the rest of it. I don't really care what people eat as long as it keeps their blood sugars at a level that won't damage their organs!

lightcan said...

It's always more complex than one simple mind thinks it is. Thank you.
Well, that means I have to be careful too.

Cathy said...

Jenny-
In reference to the blood sugar post-prandial target range chart on your site 101, you show under 140 at 1 hr. post-prandial, and under 120 for the 2 hr. reading. Yet on this blog and elsewhere you say under 140 for 2-hr. Big difference for some of us.

Jenny said...

Cathy, Most of the research points to 140 at 2 hours on a Glucose Tolerance Test as the limit for complications and that's the level the American Association of Clinical Endocrinologists endorses.

However, heart disease starts to show up when post-meal sugars are over 155 mg/dl and the A1c rises out of the middle 5%s, so that's why a bunch of us years ago (the original "5% Club" came up with the lower standard--under 140 at all times and 120 at one hour.

If you can reach it, the lower number is best, but if you can't under 140 is still better than anything the ADA recommends.

RC said...

Statin Use and Risk of Diabetes Mellitus in Postmenopausal Women in the Women's Health Initiative. Arch Intern Med. 2012 Jan 10. http://www.ncbi.nlm.nih.gov/pubmed/22231607