Richard G. Petty, MD

Nutrition and Female Fertility

Whoever said that “you are what you eat” was not wrong. The composition of our diets can affect everything from our moods to our risk of getting some types of cancer.

Now it looks as if nutrition may also be an essential part of helping at least one type of infertility.

There are literally hundreds of causes of infertility, but one of the more common ones in women is a problem with ovulation. A rapidly growing cause of ovulatory problems is the polycystic ovarian syndrome, which is itself associated with insulin resistance.

New research from Harvard School of Public Health is published today in the prestigious journal Obstetrics & Gynecology which suggests that women who followed a combination of five or more lifestyle factors, including changing specific aspects of their diets, had more than 80 percent less relative risk of infertility due to ovulatory disorders when compared with women on more unhealthy diets.

The investigators followed a group of 17,544 married women who were participating in the Nurses’ Health Study II, which is based at the Brigham and Women’s Hospital in Boston. The researchers created a scoring system on dietary and lifestyle factors that previous studies have found to predict ovulatory disorder infertility. Among those factors were:

  • The ratio of mono-unsaturated to trans fats in diet
  • Consumption of animal or vegetable protein consumption
  • Carbohydrates consumption, which included both dietary fiber the glycemic index of foods
  • Dairy consumption: both low- and high-fat
  • Iron consumption
  • Multivitamin use
  • Body mass index
  • Level of physical activity

The researchers then assigned a “fertility diet” score of one to five points. The higher the score, the lower the risk of infertility associated with ovulatory disorders.

The women with the highest fertility diet scores ate:

  • Less trans fat
  • Less sugar from simple carbohydrates
  • More vegetable than animal protein
  • More fiber and iron
  • More multivitamins
  • More high-fat dairy products and less low-fat dairy products

The more fertile women also had a lower BMI and exercised for longer periods of time each day.

This relationship between a higher “fertility diet” score and lesser risk for infertility was similar for different subgroups of women. It seemed to hold in many different age groups, and whether or not a woman had been pregnant in the past.

The effect size is impressive: women following five or more low-risk dietary and lifestyle habits have a six fold reduction in ovulatory infertility risk compared with women following none of them.

There are two surprises here. It has been believed that heavier – though not obese – women tended to be more fertile. That is not what this study found. Second, the higher fertility rates of women who consume high-fat dairy products and less low-fat dairy products may seem counter-intuitive. But well-nourished women would be expected to have a higher chance of being fertile.

The take home message is this: if a woman is having problems with ovulation, sensible dietary choices and a moderate amount of physical activity may make a large difference in her chance of becoming fertile.

This all makes sense. From an evolutionary perspective it could be dangerous to bear a child while ingesting foods, chemical or toxins that could harm a baby, or could compromise the health of a pregnant mother.

“Nutrition can be compared with a chain in which all essential items are separate links. We know what happens if one link of a chain is weak or is missing. The whole chain falls apart.”
–Patrick Wright (American Director of the Institute for Research on Food-related Disease)

“Health requires healthy food.”
–Roger Williams (Indian-born American Chemist who did pioneering work on the Vitamin B Complex, 1893-1988)


When talking about chromium we’re not talking about that stuff that gets applied to metals to make them shiny.

For more than 20 years I’ve been interested and intrigued by its role in metabolism. This month’s issue of Harvard Men’s Health Watch highlights some of the research indicating possible links between chromium deficiency and diabetes, high cholesterol, heart disease and weight management.

The journal is only available for subscribers, but let me summarize some of the data for you.

Chromium exists in many forms and not all are either absorbed or biologically active. Antacids, phytates found in grains and tannins found in tea may all lower the absorption of chromium.

A point that always comes up when we discuss supplements is that some people will feel that recommended daily allowances are too low and that using larger – sometimes vast – amounts will achieve additional biological effects. There is some evidence that very large amounts of chromium may damage cells in tissue culture but very little evidence for chromium toxicity in humans. People probably vary greatly in their tolerance to chromium.

  1. Diabetes: Chromium has attracted most interest because of its action on the binding of insulin to at least one of the insulin receptors. Insulin is more effective if chromium is present. Chromium also has a positive influence on one of the glucose transporters in cultured fat cells. The effects of chromium on glucose and insulin seems to vary in different species. So it is difficult to extrapolate from an animal study to humans. In people with both the major types of diabetes, the consensus seems to be that chromium supplements containing 200-1,000 mcg chromium as chromium picolinate a day have been found to improve blood glucose control. Chromium picolinate is the most efficacious form of chromium supplementation. There is a small pilot study that found that in women with polycystic ovarian syndrome, a low dosage of chromium picolinate improved glucose tolerance, but did not help with the hormonal or ovulatory disturbances. This has just been confirmed in a study using a higher dosage (1,000 mcg/day). Based on a detailed review of the literature, the United States Food and Drug Administration (FDA) has determined that chromium – at least chromium picolinate – does not reduce the risk that you might develop insulin resistance or diabetes and the American Diabetes Association agrees that the benefit of chromium supplements has not been conclusively demonstrated.
  2. Cholesterol: Chromium deficient rats develop high cholesterol levels. But the evidence that chromium supplementation helps cholesterol levels in humans is thin. Chromium may also help people with diabetes to lower their cholesterol levels. The published evidence indicates that any beneficial effects of chromium on cholesterol is much smaller than the effects of diet and exercise.
  3. Coronary artery disease: There is a study suggesting a correlation between chromium levels and the risk of having a heart attack, with lower levels being associated with higher heart attack risk. That does not, of course, necessarily mean that taking chromium supplements will reduce the risk of a heart attack.
  4. Weight management: Despite all the advertisements, chromium supplements have not been shown to be effective in producing sustained weight loss.

There remains a possibility that some other form of chromium may be more effective on some of these parameters. There has recently been some interest in a product called Diachrome, that contains chromium and biotin. There have been several very interesting presentations about it at international meetings, but we need to see if the results pass peer review and replication.

A diet containing plenty of whole grains, nuts, broccoli, and green beans, should provide you with enough chromium. Chances are that taking a supplement will not cause harm and may perhaps help if you are at high risk of diabetes. But the evidence is still controversial.

I know of several other studies that are underway, and I shall report them to you as they appear.

But for now, when it comes to buying supplements, this is another one of those times that I say, “Caveat emptor!

Hormonal Disturbances and Bulimia

Bulimia, more accurately called bulimia nervosa, is an eating disorder that was first described by  Professor Gerald Russell in 1977 whilst he worked at the Royal Free Hospital,in London in 1977.

There are five criteria that have to be met for someone to be diagnosed with bulimia nervosa:

  1. Recurrent episodes of binge eating. An episode of binge eating is characterized by both of the following:
    • Eating, in a discrete period of time (e.g., within any two-hour period), an amount of food that is definitely larger than most people would eat during a similar period of time and under similar circumstances.
    • A sense of lack of control over eating during the episode (e.g., a feeling that one cannot stop eating or control what or how much one is eating).
  2. Recurrent inappropriate compensatory behavior in order to prevent weight gain, such as self-induced vomiting; misuse of laxatives, diuretics or other medications; fasting; or excessive exercise.
  3. The binge eating and inappropriate compensatory behaviors both occur, on average, at least twice a week for three months.
  4. Self-evaluation is unduly influenced by body shape and weight.
  5. The disturbance does not occur exclusively during episodes of anorexia nervosa.

It has long been known that there can be a number of hormonal disturbances in people with both anorexia nervosa and bulimia, but it has never been clear whether they are a result of malnutrition, vomiting and/or the use of laxatives and diuretics. When we were both at the Maudsley Hospital in London, Gerald and I once spent several hours talking through the possibilities of doing some collaborative work on the hormonal problems in people with eating disorders. The list of disturbances was so long that we decided that we had other priorities.

So I am fascinated to see some new research from the Karolinska Hospital in Stockholm.

Amongst the most prominent problems in people with bulimia are menstrual irregularities and increased rates of polycystic ovarian syndrome (PCOS). A Dr Sabine Naessén studied 77 women with bulimia and 59 healthy volunteers.

As expected the women with bulimia had higher rates of menstrual disturbances, hirsutism and PCOS. And in line with previous research, levels of testosterone correlated with amounts of hirsutism.

The women with bulimia also had lower bone density, particularly if their menstrual cycles had stopped or if they had ever had anorexia nervosa.

She also found an association between two common polymorphisms in the estrogen receptor (ER) β gene and bulimia. She has speculated that this genetic variation might predispose women to the development of bulimia.

Her results suggest that some women with the condition may have too much of the male hormone testosterone. Half of the people treated for this imbalance reported less hunger, and fewer cravings for fatty and sugary foods.

This is important work. It is highly unlikely that eating disorders could ever be reduced to biochemical disturbances in the brain. There are so many environmental factors, for instance sexual abuse or other types of trauma, and even social pressure, that have been implicated in the etiology of the illness.

But the key point is this: why do some people develop an eating disorder after trauma while other do not? And why do some people develop eating disorders, even when they have never been traumatized in their lives?

The answer as always lies in the ways in which genes and the environment interact. If confirmed, this research may point the way toward some new ways of helping some people with this group of illnesses.

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