A new study from researchers in the Netherlands has found that women who closely follow a Mediterranean-style diet may have a higher likelihood of successfully becoming pregnant after an infertility treatment.

The study followed 161 couples who were having either in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) at the Erasmus University Medical Center in Rotterdam. The couples were asked questions about their usual diets and found that the group of women who scored highest in adherence to a Mediterranean style diet had a pregnancy rate of 30% following the fertility treatment. Among women who ate diets most unlike the Mediterranean diet had a 25% success rate.

There is not one specific “Mediterranean Diet,” because of variations between the 16 countries in the region that surround the Mediterranean Sea, such as culture, agriculture, and economy. However, the dietary pattern generally has the following characteristics:

• High consumption of fruits, vegetables, bread and other cereals, potatoes, beans, nuts and seeds
• Olive oil is an important monounsaturated fat source
• Herbs and spices for flavoring instead of salt
• Fish is consumed at least two times a week
• Dairy products, eggs, and poultry are consumed in low to moderate amounts, and little red meat is eaten
• Wine is consumed in low to moderate amounts
• The Mediterranean lifestyle also promotes exercise and sharing meals with family and friends.

The authors suggested several theories regarding the association between increased fertility and the Mediterranean diet. One is that women who choose more unsaturated oils that are balanced between omega 3 and omega 6 fatty acids. Omega 6’s are precursors to prostaglandins which are involved in the menstrual cycle, ovulation, and pregnancy maintenance, but too much can lead to inflammation and other health concerns. The study also found that women who consumed a Mediterranean style diet had higher levels of B6 stores, which may increase the chance of conception according to a previous study.

Some studies suggest that a Mediterranean style diet may help women who are having trouble becoming pregnant due to a condition called polycystic ovarian syndrome or PCOS, a common cause for ovulation problems that lead to female infertility. It occurs in about 8-10% of women in their child-bearing years. The diet may help by stimulating weight loss and reducing inflammation, both of which exacerbate the condition.

For example, a Mediterranean style diet focuses more on fresh, whole fruits and vegetables and healthy grains and complex carbohydrates. Refined sugars and processed foods in the diet can lead to excessive levels of blood glucose which leads to inflammation. In a study at the Schwartz Center for Metabolism and Nutrition at Case Western University, women with PCOS who consumed sugar had higher levels of free radicals, higher levels of insulin resistance, and elevated levels of male hormones that led to an inflammatory state.

In addition, a diet high in saturated fat is linked to an elevated C-Reactive Protein (CRP) level which impairs insulin signaling in the part of the brain responsible for weight balance.

While the study is preliminary and based on observational data, rather than proving cause and effect, women should understand that the diet will not work for everyone attempting pregnancy. However, the diet is healthful for all adults, and is certainly recommended as a overall healthy eating pattern.