Tuesday, December 04, 2007

Don't Buy Their Snake Oil

If researchers from Harvard University - Dr. Jorge Chavarro and Dr. Walter Willett - had merely published their data and encouraged additional study to validate their findings, I'd have nothing to write about today. In fact, I may have penned a quick post about the study since it did find some intriguing associations between diet and risk of infertility in women participating in the Nurse's Health Study II.

But, they didn't simply publish a paper. No, they also published a book - The Fertility Diet - that is now featured on the cover of Newsweek and also being touted in the media as the low-tech, do-it-yourself way to prevent and even reverse ovulatory infertility!

Worse though is the media advancing the findings in a way that implies the dietary strategy has been tested in infertile women!

Take a look at how MedScape opened their article - "Higher intake of monounsaturated fats; vegetable protein; and high-fiber, low-glycemic carbohydrates improved fertility outcomes in women with ovulatory disorder infertility, according to the results of a cohort study reported in the November issue of Obstetrics & Gynecology."

The data is not from women who specifically had a diagnosis of ovulatory dysfunction (irregular or absent menstruation). Rather, the data was from a cohort of women within the Nurse's Health Study II who were identified as actively trying to get pregnant during the period of follow-up data collection. That is a very different cohort of subjects than one exclusively made up of women with infertility, or a cohort designed as a comparison study of women with and without fertility issues due to ovulation!

But the thing that really irks me is the media falling all over itself to highlight one finding in particular, the supposed reduction of ovulatory dysfunction if women follow the dietary strategy outlined in the book - "their research shows that women who follow five or more of the tips could boost their fertility by up to 80 percent," is how the Boston Channel presented it.

Charles Platkin (Diet Detective) wrote, "In fact, the Nurses’ Health study showed that those who did not follow a healthy diet were six times more likely to experience infertility related to ovulation than women who did."

Oh really?

How about we look at the published data - let's look specifically at those cases with ovulatory disorder infertility published in the study:
Diet Score .Cases .RR (95% CI)
Q1 (lowest) _117 _1.00
Q2 _100 _0.68 (0.52 - 0.89)
Q3 _77 _0.65 (0.48 - 0.87)
Q4 _80 _0.53 (0.40 - 0.72)
Q5 _42 _0.34 (0.23 - 0.48)

Do you see a six-fold difference between Q1 and Q5? I didn't think so!

Do you see an 80% greater chance of pregnancy in those in Q5 than those in Q1? I didn't think so!

And as an aside - I don't get is how in Q4 they reported more cases of infertility, yet managed to report a lower RR? Anyone want to help me out with that one?

Anyway, I was scratching my head, trying to figure out how they came up with these incredible numbers - statistics being used to heavily promote the book right now - and they're in the study all right, in a theoretical computer model (which should be called a fantasy search for significance) run with different scenarios of possibilities, not data of real women eating in the real world!

As the researchers noted in their paper, "we calculated the population attributable risk associated with specific combinations of dietary and lifestyle factors to estimate the proportion of cases that may have been avoided had all the women in this cohort adhered to these habits."

So now, rather than state these numbers are based on computer models and are, at best, theoretical - they're promoting the book as if it's fact that the dietary strategies actually work.

And they're doing it in a way that is promoting the idea that a woman with ovulatory dysfunction can fix it herself, without medical intervention, and get pregnant on her own.

To say this is a travesty for women's health is an understatement!

Just when you think it's not possible, it really does get worse.

If the promotion of theoretical as fact isn't bad enough, here is a real hard fact that should send chills up your spine - while the majority of cases of ovulatory dysfunction are attributed to PCOS (polycystic ovarian syndrome), a large enough number are due to hyperprolactenemia, usually cased by a small tumor at the base of the brain. Yet, the book has absolutely no warning to women that a diagnosis for the cause of ovulatory dysfunction is critical before beginning the do-it-yourself diet approach.

Think about that for a moment.

Then consider that ovulatory dysfunction can also be due to disease of the pituitary, adrenal or thyroid glands. It can also be due to premature ovarian failure (premature menopause).

Without a diagnosis, you're flying blind as to cause and without any warning in the book about the many causes of ovulatory dysfunction, you may in fact be delaying critical medical intervention to resolve the problem if you simply take the book and run with the recommendations.

Oh and it just keeps going too. Also noticeably absent is any warning to women already experiencing ovulatory dysfunction that continuing to attempt pregnancy in the absence of regular menstruation is futile. In fact the book promotes the standard advice that one year of trying to get pregnant is recommended unless one is over 35, then six months of trying is appropriate before seeking a medical evaluation.

When a woman has a regular cycle, this advice is fine - when she has absent or irregular periods, she's wasting precious time continuing along and trying without a diagnosis because without ovulation there cannot be a pregnancy!

One recommendation in particular can also be problematic for a woman already experiencing ovulatory dysfunction - the recommendation to increase iron intake. You see, if the researchers who wrote the book bothered to look at the literature, they'd have learned that women with ovulatory dysfunction often have elevated stores of iron. As the researchers in the above linked study noted, "Because the periodic blood loss resulting from regular menstruation protects pre-menopausal women against excessive iron accumulation, oligomenorrhea and amenorrhea might contribute to the increase in ferritin observed in overweight and obese PCOS patients. When studying PCOS patients and control subjects as a whole, ferritin levels were increased in women with amenorrhea compared with women with regular menstrual cycles, whereas women with oligomenorrhea presented with intermediate values (means ± SD: amenorrhea 159 ± 144 pmol/l, oligomenorrhea 114 ± 95 pmol/l, and regular menstrual cycles 83 ± 51 pmol/l; F = 3.295, P = 0.040)."

Also of note is the fact that in the book they recommend reducing saturated fat intake to less than 8% of calories.

Where, pray tell, is the data to support that recommendation?

It certainly isn't in their published paper. In their published data, the women with the lowest risk of infertility not only consumed the highest level of total fat, but their intake of saturated fat was also higher than the other groups - in fact, their saturated fat intake accounted for 11.5% of calories.

But hey, let's not let the actual data get in the way of recommendations that align with the author's previous book, Eat, Drink and Be Healthy!

While we're at it, where is the data to support eating less meat? Their published data found absolutely no difference in heme iron intake between the various groups - none at all - yet they're promoting the idea that reducing red meat in the diet is going to make a difference in getting pregnant. Their data does not support this idea; and add to that this idea has not even been tested in women attempting to get pregnant, yet that doesn't stop them from making the recommendation.

Worse though (can it really get worse?) is the inclusion within the book of the politically correct idea that reducing or even eliminating red meat is better for the environment - who needs data when you can convince women to limit or eliminate red meat on emotion.

If you're a woman wanting to get pregnant, do you want to based your diet on politically correct advice or hard evidence?

Do you want to make changes to your diet based on theoretical computer models, or data from studies that have actually investigated how a change to diet improved pregnancy rates in those participating in the study?

As Albert Einstein once pointed out, "Only two things are infinite, the universe and human stupidity, and I’m not sure about the former."

Stupidity or just plain old ignorance contributes greatly to the millions of people who succumb daily to the latest or most heavily promoted "facts" generated by epidemiologist's findings concerning diet. Today it happens to be diet and fertility, tomorrow it'll be diet and aging, the next day diet and cancer.

The problem though, with such data from epidemiological studies on diet and lifestyle, remains (and will forever remain) that correlation does not imply causation. I don't know how many times that can be repeated, but it is true and will always be true. Just as it is true that eating red meat does not cause ovulatory dysfunction anymore than consuming high levels of non-heme iron prevents it. Just as consuming regular ice cream does not make you fertile anymore than restricting saturated fat to less than 8% of your calories will make you get pregnant.

That the media is heavily promoting this book only tells us one thing - they don't understand science, the scientific method, or the difference between correlation and causation. And they certainly have not read the study in full and then compared it to the book's recommendations.

No doubt the findings are intriguing, but they do not make a proven strategy or evidence-based approach to prevent or reverse ovulatory dysfunction.

What they do provide is a starting point to actually test the dietary strategies in women with ovulatory dysfunction. Until those studies are conducted, the book is merely speculation, potentially a waste of precious time or worse for a woman with ovulatory dysfunction.

On this book I have to strongly suggest taking a pass and instead do what's best - go to the doctor if you're having problems getting pregnant or have irregular or absent periods. Without a diagnosis, you're flying blind on assumptions - it's better to have a diagnosis and tackle the problem based on facts rather than guessing what's wrong. It's true that you can make changes in your diet and see improvement, just as it's true that if your ovulatory dysfunction is caused by a tumor your diet isn't going to make a difference.

Just because the book is from esteemed researchers at Harvard doesn't mean it isn't snake oil.


  1. Anonymous10:30 AM

    Another great post, Regina. It's good to see you posting again!

  2. Great response, Regina. Have you thought of sending an abbreviated version to Newsweek, or linking to it from their message board on the subject? The public should know about this before they go out and by the silly book.

  3. Hi Regina,
    I agree that all people should take responsible care of their health. This is including women with fertility abnormalities, whether or not they are attempting pregnancy should definitely see a physician to rule out more serious conditions that must be treated (personally, I have had amenorrhea for years after weight loss, and I would follow my own advice if not for the fact I've no insurance... plus, I am almost certain it is hypothalamic amenorrhea based on the lab results I have seen ... but that's another issue).

    However, I just wanted to argue a few points... first, the recommendation for women to take iron is valid IMO. High stores of iron in PCOS women are often a symptom of hyperinsulinemia and insulin resistance syndrome (as well as a cuasative factor). A high hemoglobin and hematocrit is also influenced by hyperinsulinemia and the high levels of androgens found in such patients.
    Giving these women more iron is not going to increase their stores, because the increase is not because of increased iron intake but from the primary hormonal derrangements (which also cause the fertility problems).

    It's like the advice to eat less fat if you are fat, or to eat less sodium if you have high blood pressure: these nutritive substances are passive in the disease process, it is high levels of insulin that are the problem.

    Considering complications related to malnutrition in pregnancy like anemia (and neural tube defects, and PIH/preeclampsia) are so rampant in our society, the advice to increase iron intake (which often goes along with recommendations to eat a nutritious diet) if hoping to conceive can only be beneficial. The poor, obese/malnourished patients are especially at risk for these kinds of birth defects and complications because their baseline diet (and health) is confounded by malnutrition and metabolic syndrome. Increasing iron is no more going to cause increased stores than increased fat or increased sodium contributes to their respective diseases (obesity and hypertension); it's mediated by insulin... and foods high in iron (and all nutrients for that matter), tend to be against hyperinsulinemia as a rule, anyway.

    Another point is that it is possible to ovulate without menstruation; it's very unlikely but possible. Estrogen is responsible for the thickening of the endometrium which is primarily responsible for the heaviness of menstrual flow; ovulation with only scant blood flow (which might be missed) can occur if estrogen isn't that high (as may be the case in some very thin women, or women on lower calorie, lower fat diets). Of course, it's always possible that ovulation can occur spontaneously (say, after initiating a LC diet in a woman with PCOS :) ) after a long period of amenorrhea... she can get pregnant at this time even though she might not see her period for another few days.

    Other than these two minor quibbles great post :) .
    It's like, seeing what Gary Taubes researched from the past, in real time present medical science. A shame, since so many people are impacted by this shoddy research and advice.

  4. Anonymous4:17 AM

    Regina, very good post. In fact, when I did research this, I agreed with much of what you said. Most experts believe that diet has about a 10 percent effect on fertility -- Here are the interviews and QA about Diet and Exercise's affect on ferility. It might help... http://www.dietdetective.com/content/view/2913/159/

  5. Considering complications related to malnutrition in pregnancy like anemia (and neural tube defects, and PIH/preeclampsia) are so rampant in our society, the advice to increase iron intake (which often goes along with recommendations to eat a nutritious diet) if hoping to conceive can only be beneficial.

    Adding iron doesn't change the underlying cause of PCOS or ovulatory dysfunction...and in a woman who may already have high levels of iron stored, adding iron provides no benefit.

    Of course, it's always possible that ovulation can occur spontaneously (say, after initiating a LC diet in a woman with PCOS :) ) after a long period of amenorrhea... she can get pregnant at this time even though she might not see her period for another few days.

    Spontaneous ovulation with low-carb happens a lot....the book however is not advocating a low-carb diet or even suggesting a large enough reduction in carbohydrate to cause spontaneous ovulation with diet alone. But you are correct, it happens - as does ovulation that is missed, although that is very rare.

  6. Anonymous11:22 AM

    Here are the interviews and QA about Diet and Exercise's affect on ferility. It might help...

    The quote looks like it was:

    "In fact, the Nurses' Health study showed that those who did not follow a healthy diet were six times more likely to experience infertility related to ovulation than women who did."

    If you look at the actual data published the above statement is untrue. By the numbers, in the cohort 416 women were identified as being diagnosed with ovulatory dysfunction.

    Of those 117 had the lowest score and represented 28% of the women with ovulatory dysfunction....the women with the highest score, 42 women, represented 10% of those with ovulatory dysfunction.

    Is that a six-fold difference?


    Did you fact check before stating the above as "fact"?


  7. I have a love hate thing for Willett. One the one hand he has done as much as any to dispel the notion that low fat diets are a disaster, and brings a credibility that few can match with his Harvard credentials. OTOH, he has this neurotic fear of red meat, and saturated fat. The part of this that I find most difficult to comprehend, is that in other publications, including a recent issue of the HARVARD HEART LETTER, he says that the fat from red meat, and coconut oil are not problematic. Maybe he is compartmentalizing?

  8. Maybe he is compartmentalizing?

    Maybe he's trying to sell a book and keeping things in line with the generally accepted - limit red meat, limit saturated fat, eat whole grains - means no criticism from the book reviewers and major media now touting it? Just a thought.

  9. Anonymous2:06 PM

    I will likely be doing damage control for the next few years due to this piece of faux "science."

    Epidemiologists are famous for forgetting that their data-mined associations are nothing more than that. There is no evidence here...just biased findings used to support biased assumptions.

    This load of crap is WORSE than wrong.

  10. I just hope Oprah doesn't get wind of this book!

    Diet and babies!! What a great cause!

    Thanks for posting on this Regina (and welcome back!). I saw the article, but only read a few lines...I'm 53 and post menopausal. But I have a niece and a friend with fairly severe PCOS and their docs aren't recommending much diet change. Neither have been told to try low carb, one is on medication for insulin resistance. They both know where I stand, but refuse to admit I may be right and low carb will help. (Neither are trying to get preg, but are suffering the pain and other symptoms associated with PCOS.)

  11. leslie12:18 PM

    It's pretty unlikely that Willett or any other MD actually _wrote_ this book. Some ghostwriter probably put the ant-red mead, anti-sat fat stuff in there and Willett didn't take it out.

  12. It's pretty unlikely that Willett or any other MD actually _wrote_ this book. Some ghostwriter probably put the ant-red mead, anti-sat fat stuff in there and Willett didn't take it out.

    That may well be, but their names are on it, they own responsibility for what they allow their names attached to. =)

  13. Something else I was thinking about this issue; I was wondering a very low carb diet plus a low weight could actually suppress fertility the same way a high carb diet increases it (this "hyperfertile" high hormone production can result in PCOS in women predisposed to glucose problems who eat a diet high in carbs + calories).

    I've been amenorrhetic since I lost to 145 lbs, and even though I eat a ton of fat and a pretty good amount of cals (about 1700-1800) ... the only thing I restrict is carb (I used to restrict cals but I'm done with that nonsense lol). I've remained amenorrhetic since then. My BMI is just a shade below the so called "fertility zone" so I don't think body fat is exclusively the problem. I've come to think that my low carb diet, which originally cured my PCOS, now contributes to infertility because I don't have enough body fat to make enough leptin for the insulin-deficit of my diet.
    (Side note; leptin is what mediates both PCOS/obesity amenorrhea and amenorrhea associated with starvation/lowweight/exercise.

    Leptin plays a major role in the abnormal LH levels in both PCOS and hypothalamic amenorrhea; leptin is increased by body fat (having stored fat) and also by a high carb diet (making fat).

    It is reasonable to assume that if someone is at a marginal weight, a high carb diet could actually enhance fertility (by insulin acting on the fat cell to make leptin).

    Lowering carbs lowers leptin, which in an obese women makes her fertile... but does it make a low weight woman INFERTILE?

    The only research on this issue has been with women who are at a good or excessive body fat level, no hx of weight loss. Of course, these women find improved fertility with lower insulin diets (their leptin levels are already too high).

    Reserach with underweight/weight loss women has shown increasing fat improves fertility... but again these women were eating high carb diets at a baseline, so that's expected (fat not only adds calories for insulin to act on but fat independently makes hormones work more effectively).

    I don't know, I was wondering what your thoughts were... considering your education and your husband's line of work you of all people could probably answer this question :) .

    If you have come across any research in this area (the effect of strict low carb on the fertility of women who are at a low or low normal weight)... I'd be interested in seeing it.

  14. Leslie7:34 PM

    You've earned it, a Thinking Blogger Award!

    The participation rules are simple:

    1. If, and only if, you get tagged, write a post with links to 5 blogs that make you think,
    2. Link to this post so that people can easily find the exact origin of the meme,
    3. Optional: Proudly display the 'Thinking Blogger Award' with a link to the post that you wrote.

    Here is your link to capture the graphic for your award:


  15. While I disagree with Willet's low sat fat, anti red meat agenda I am absolutely horrified by the unethical way this book publicity and the "study" results have been conducted. This should be a Medical Council matter due to the egregious abuse of his position.
    Thanks Regina for your sane post.
    Anecdotally, I am an have always been underweight, but that did not affect fecundity one bit; my second pregnancy occurred when my BMI was only 15.5kg/m2! I have always eaten low carb by choice - long before knowing anything about nutrition - simply by choice. I obviously do not homogeneously fit the leptin research.