"Let food be thy medicine, and medicine be thy food"
~Hippocrates
Dietary habits have an immense impact on overall health. Our diet can influence so many major organ systems, from our cardiovascular, joint, neurological, digestive, skin, to hormonal health. And Yes, it can influence our reproductive health as well.
With new fad diets on the rise every few months, it can easily become very confusing to ascertain which dietary lifestyle is best to support you on your fertility journey. Overall, the scientific research evaluating the impact of dietary changes on reproductive health is rather small, but the majority of the research done so far is showing some consistency, meaning that we are starting to see a trend on what may be best for individuals undergoing fertility treatments.
There is a vital chain of hormone secreting glands known as the Hypothalamic-Pituitary-Ovarian (HPO) axis that is in charge of regulating the production of follicle stimulating hormone (FSH), luteinizing hormone (LH), estrogen (E), and Progesterone (P). This is the axis that can become disrupted from different dietary habits.
A recent review evaluating collective evidence of dietary fat found that high dietary fat intake, with or without obesity, will impair the functioning of the HPO axis and fertility.
On average, a "high fat diet" is defined as 35% or more of your caloric intake being from dietary fats. So, for example, if you consume about 2000 calories on an average day, and 800 of those calories are from dietary fat then about 40% of your total caloric intake is from dietary fats. And be definition, it may be too high and may interfere with the smooth functioning of the HPO axis, specifically it can contribute to Ovulatory Dysfunction.
Effect on Assisted Reproductive Technologies (ARTs):
1. A trial observing the quality of oocytes found that high fat diets were associated with increased fragmentation. The higher the fragmentation rate, the lower the quality grade assigned to the embryo.
2. Another study observing the effect of high fat diets on ART outcomes found that the high fat diets were associated with an increased number of oocytes retrieved, but also associated with a decrease in the quality of oocytes.
So How does a High Fat Diet actually affect Fertility?
1. High fat diets can lead to insulin resistance systemically. This means that more insulin is required to have the same level of effect in the muscle and in other tissues as well. Basically there is a desensitization process that occurs in the insulin receptors in these tissues, and they need a stronger signal to function. The issue is that the insulin receptors in the tissue in the HPO axis do not undergo a desensitization process like the liver and muscle. The result is that there is a higher amount of insulin circulating in the blood and it is over-stimulating the HPO axis glands. The increased signal from insulin on these tissues results in an increased pulse amplitude of gonadotropin releasing hormone (GnRH) from the hypothalamus to the pituitary gland, and may result in an increased production of LH.
2. The increase in dietary fat can alter genetic expression of various enzymes. Particularly it may influence the production of aromatase, the enzyme found in fat tissues and in the ovaries that is responsible for converting testosterone to estrogen. In mice studies it was also found that the number of developing follicles in the ovary decreased and that the ovulatory cycles became irregular.
3. Increased levels of leptin occur in response to a high fat diet. The leptin can interfere with the HPO axis by decreasing the GnRH released from the hypothalamus. The elevated levels of leptin may also affect the ovary be decreasing the production of the aromatase enzyme, and decreasing estrogen production.
Limitation:
The limitation of the research is that the majority of studies are animal studies, so they do not always translate to a predictable effect in Humans. The studies observing fat intake in humans and associations with ovulatory dysfunction are lacking and those that are available show conflicting results.
Take-away message:
Aim for a healthy and balanced diet and have healthy amounts of fat, as they are necessary for steroidogenesis (hormone production). Try your best to have healthy fats (omega 3s, olive oil, coconut oil, etc.) and avoid trans fats. Do a simple total caloric check based on your typical daily food intake to make sure your total fat intake is between 25-35% of your total daily caloric intake. Working with a Naturopathic Doctor, Nutritionist, and/or Dietician can be helpful to do this thoroughly.
This article is in no way a replacement for medical advice or medical care, it is advised that anyone concerned about their Health should speak with their Naturopathic Doctor or Primary Care Provider.
Reference:
1. Hohos, N. M., & Skaznik-Wikiel, M. E. (2017). High Fat Diet and Female Fertility. Endocrinology.