Endometriosis, a chronic inflammatory condition, is characterized by the presence of endometrial-like tissue outside the uterus. This condition affects a significant portion of women, impacting their overall quality of life and fertility. This article explores the intricate relationship between diet, endometriosis, and fertility, drawing upon various research findings and dietary approaches.
Introduction to Endometriosis
Endometriosis is a chronic disease with an inflammatory nature, defined by the presence of ectopic glands and stroma similar to endometrial tissue. It is estimated to impact between six and ten percent of women, with a prevalence believed to exceed 33% in patients experiencing acute pelvic pain. Common symptoms associated with endometriosis include severe menstrual pain, increased menstrual bleeding, chronic and intense pelvic pain, painful intercourse, and decreased fertility. Risk factors such as early menarche, shortened menstrual cycle duration, and nulliparity are all associated with elevated levels of circulating estrogen concentrations and are also linked to an increased risk of developing endometriosis.
Several recognized risk factors for endometriosis share a common thread of increased exposure to estrogens. This heightened exposure, coupled with in-situ estrogen secretion and circulating estrogen, can stimulate the proliferation of ectopic endometrial tissue, which may be a potent risk factor for endometriosis. The pathogenesis of endometriosis has been reviewed by several hypotheses, with retrograde menstruation being the most widely accepted theory. However, the exact cause of endometriosis remains unknown. The treatment of these symptoms lacks a standardized approach, and the disease has the potential to recur even after appropriate surgical or pharmacological interventions. Therefore, affected women may benefit from research on lifestyle factors or potential strategies for prevention, modification, or treatment of the condition.
The Role of Nutrition in Endometriosis
The impact of nutrition on the development and progression of endometriosis has been reviewed recently. The disease nature, such as inflammatory and estrogen activity, menstrual cycles, and the biochemistry of prostaglandin, can be influenced by dietary choices. Studies have suggested that consuming fiber may enhance the elimination of estrogen, potentially reducing the risk of endometriosis. Besides, lowering the intake of dietary fat can also decrease serum estrogen levels. Furthermore, plant-based diets, with their anti-inflammatory nature, have been found to be associated with an increased level of sex-hormone binding globulin, reducing the amount of bio-available estrogen present in the body. On the other hand, meat intake is shown to be related to a higher risk of endometriosis. In addition, recent research indicated that following an anti-inflammatory diet is a viable option for managing endometriosis symptoms. Finally, when comparing the foods and drinks recommended in most national dietary guidelines to the components of inflammatory indices, they closely resemble an anti-inflammatory diet. Although there is insufficient evidence to support a superior diet for the management of endometriosis; however, the Mediterranean diet may have the most benefit without nutrition concerns.
MIND Diet and Endometriosis
The MIND diet (Mediterranean-dietary approach to stop hypertension (DASH) diet intervention for neurodegenerative delay), which benefits from the principals of the Mediterranean and DASH diets, is a low fat, anti-inflammatory dietary pattern, rich in high fiber food items. In addition to sharing similarities with the Mediterranean diet, the MIND diet is stricter about avoiding red meat, butter, fried foods, and sweets, which are high fat inflammatory food items. Therefore, it appears that the MIND dietary pattern has the necessary components to protect an individual against the odds of endometriosis, based on the literature, and even has advantages over the Mediterranean diet in terms of meat and fat restriction.
Read also: Nutrition for Endometriosis
To further investigate the correlation between the MIND diet and the risk of endometriosis, a study was conducted to explore the association between the MIND diet and the odds of endometriosis.
Dietary Patterns and Endometriosis Risk
Emerging evidence indicates that dietary patterns may modulate the inflammatory environment associated with endometriosis, potentially influencing symptom severity by affecting oxidative stress, estrogen metabolism, and levels of sex hormone-binding globulin (SHBG). Diets rich in antioxidants, polyunsaturated fatty acids (PUFAs), and vitamins D, C, and E-alongside the avoidance of processed foods, red meat, and animal fats-may offer beneficial effects. Notably, dietary approaches may serve not only to alleviate pain and improve fertility outcomes but also to reduce lesion growth and recurrence, particularly in patients seeking pregnancy or those unable to undergo hormonal therapy due to contraindications. Furthermore, nutritional strategies may enhance postoperative recovery and act as a viable first-line therapy when conventional treatments are not applicable.
Study on MIND Diet and Endometriosis
A case-control study was conducted in hospitals, involving interviews with 115 individuals recently diagnosed with endometriosis and 230 control subjects in Tehran, Iran, from February to September 2021. Female participants, aged 18 to 49, were free of any underlying health conditions that could impact the study findings (non-pregnant and lactating, non-menopausal not afflicted with diet related chronic diseases such as cancer, diabetes, cardiovascular disease and etc.). Any endometriosis patient that diagnosed by surgery, macroscopically or with histological examination, considered as case group. Also, for the control group, the same criteria was considered, except for the presence of endometriosis. All participants in both case and control groups were confirmed by a blinded gynecologist.
Dietary Assessments
The assessment of dietary intake relied on a validated 168-item Food Frequency Questionnaire (FFQ) and a validated food album supplemented with visuals of household measurements. Interviews and surveys were conducted by an impartial interviewer, blinded to the participants’ outcomes, to minimize potential information bias. Dietary intake of study participants were assess by their intakes through the year prior to interview (controls) or endometriosis diagnosis (cases). The interview participants were provided with information regarding the typical size of each food item. Following this, they shared how frequently they consumed each food item on a daily, weekly, or monthly basis. These consumption frequencies were then converted into grams using a reference scale for home food measurements. Then, calculation of daily energy and macronutrient intake was carried out using either the USDA food composition table or the Iranian food composition table.
MIND Diet Score Calculation
The MIND diet calculation was done based on food intake of FFQ items. At first, 15 good groups created based on 168 items of FFQ: 10 healthy food (green leafy vegetables, other vegetables, nuts, legumes, berries, whole grains, poultry, fish and olive) and 5 unhealthy groups (red meat, butter and margarine, cheese, desserts and fast foods). In this study, wine consumption was excluded due to the absence of relevant data in the original dataset. Dietary intakes were then divided into tertiles, and healthy food groups were scored as follows: a score of 0 for the first tertile, 0.5 for the second tertile, and 1 for the third tertile. For unhealthy food groups, reverse scoring was applied: a score of 1 for the first tertile, 0.5 for the second tertile, and 0 for the third tertile. Finally, the overall score was calculated by summing the scores of 14 food groups, resulting in a total score ranging from 0 to 14.
Read also: The Keto-Endometriosis Link
Statistical Analysis
The statistical analysis was conducted using SPSS (Statistical Package for the Social Sciences program; version 22; Chicago, IL, USA). Two-tailed analyses were performed, and p-values < 0.05 were considered statistically significant. Prior to further analysis, continuous variables were checked for normal distribution through skewness, histogram, Q-Q plots, and the Kolmogorov-Smirnov test. Normally distributed quantitative variables were expressed as mean (SD), and non-normally distributed ones as median (25 th −75 th). Categorical demographic characteristics were presented as frequency and percentages. The Chi-square test was utilized to compare qualitative data between endometriosis patients and controls. The Mann-Whitney U test was employed to compare non-normally distributed quantitative variables, respectively, between the two groups. Logistic regression was used to estimate odds ratios (OR) for endometriosis, with a 95% confidence interval (CI). Multivariable logistic regression models were adjusted for age (years), age at menarche (years), physical activity (MET-hours/day), body mass index (kg/m²), total energy intake (kcal/day), menstrual history (regular vs. irregular), cigarette smoking status (never, past, or current smoker), family history of endometriosis (yes/no), OCP (yes/no) and number of pregnancy (0, 1-2 and ≥ 3).
Results of the MIND Diet Study
Out of 317 participants, 4 were excluded due to discrepancies in energy intake. The final analysis included 105 cases of endometriosis and 208 healthy controls, with no significant age differences between the groups. Education level was significantly different between two groups of lowest and highest adherence to the MIND diet in participants with endometriosis. Also, in the healthy controls, the mean of BMI and WC were significantly higher in the group of lowest adherence to the MIND diet in comparison to the other group.
In the group by highest adherence to the MIND diet score, higher intake of energy, protein, green leafy vegetables, other vegetables, nuts, berries, whole grains, poultry, fish, olive and MIND diet total score, and lower intake of red meat, desserts and fats foods were seen in participants with endometriosis. Also, in the control group, higher intake of fiber, green leafy vegetables, other vegetables, nuts, berries, poultry, fish, olive and MIND diet total score, and lower intake of cheese and desserts were observed in the group by highest adherence to the MIND diet score.
In continuous association, a lower odds of endometriosis were found by each unit increase in MIND diet score in both crude and adjusted models. Also, in categorical association, lower odds of endometriosis were seen in the highest than median score of MIND diet in comparison to the lowest one in both crude and adjusted models.
Furthermore, based on the results of the adjusted model, lower odds of endometriosis were found in the group by the highest intake of green leafy vegetables, other vegetables, nuts, legumes, berries, and fish in comparison to the other group. But, in comparison to the lowest intake group, higher odds of endometriosis were seen in the group by the highest intake of red meats and butter and margarine.
Read also: Endometriosis & Weight Management
Discussion of the MIND Diet Study
The results showed that high adherence to the MIND diet, as well as higher consumption of green leafy vegetables, other vegetables, nuts, legumes, berries and fish are associated with a lower odds of endometriosis, while higher intake of whole grains, red meat, butter and margarine increases the likelihood of endometriosis. Notably, no clear association has been found between endometriosis and the consumption of berries, poultry, olives, cheese, desserts, and fast food.
Alternative Healthy Eating Index (AHEI) and Endometriosis
To further explore the relationship between diet and endometriosis, another study examined the association between the Alternative Healthy Eating Index (AHEI) and the likelihood of experiencing endometriosis among women in Iran.
Methods of the AHEI Study
Conducted as a hospital-centered case-control investigation, the study enlisted individuals diagnosed with endometriosis alongside healthy counterparts, confirmed by a gynecologist, between February and September 2021 in Tehran, Iran. The pattern of diet was assessed utilizing a validated Food Frequency Questionnaire (FFQ) encompassing 168 food items. Logistic regression models were employed to explore the potential connection between AHEI and the probability of endometriosis.
The AHEI is based on the original healthy eating index formulated by Kennedy et al., with some modifications. Eleven elements, such as fruits, vegetables, whole grains, nuts, legumes, long-chain n-3 fatty acids (DHA and EPA), polyunsaturated fatty acids (PUFA), wine, sugar-sweetened beverages and fruit juice, red and processed meats, as well as trans-fat and sodium are included in this dietary pattern. In the current study, sufficient data on whole grains, wine, and long-chain n-3 fatty acids (DHA and EPA) consumption was not available, so the AHEI was computed based on eight components. Individuals positioned in the top decile for vegetables, fruits, nuts, legumes, and PUFA received a maximum score of 10, whereas those with the lowest intake were assigned a score of 1. Participants falling into other deciles were allocated scores proportionate to their consumption levels. A totally converse calculation method was performed for the intakes of sugar-sweetened beverages and fruit juice, red and processed meats, trans fatty acids, and sodium. These ten components were summed to determine the overall AHEI score for each participant. The range was between 8 and 80.
Results of the AHEI Study
The analysis encompassed 105 subjects with endometriosis and 208 individuals in good health. No significant differences were observed between those with low and high adherence to the AHEI in both endometriosis and healthy groups regarding age (years), and age at menarche (years). In healthy controls, patients with high adherence to the AHEI had higher weight, BMI and waist circumference (WC). In patients with endometriosis, those with low adherence to the AHEI had higher weight (kg) and BMI (kg/m2).
Healthy control subjects demonstrated a significantly elevated AHEI score. The consumption of fruits, vegetables, and legumes was notably higher in these healthy controls. Conversely, the intake of meat, trans fatty acids, fruit juice, and sodium was significantly greater in individuals with endometriosis.
The crude model showed that those with the highest intake of fruits, vegetables, and legumes had lower odds of endometriosis. Higher adherence to the AHEI was associated with a lower odds of endometriosis as shown in the crude model. Conversely, the crude model showed a direct association between intakes of meat, trans fatty acids, and sodium and odds of endometriosis. The results remained significant in both partially and fully adjusted models for fruits, vegetables legumes and AHEI score. High consumption of meat, trans fatty acids, and sodium remained risk factors for endometriosis in partially and fully adjusted models.
The logistic regression model results indicated that with each unit increase in the AHEI score, the odds of endometriosis decreased by approximately 19%. Furthermore, a gram increase in the intake of fruits and vegetables corresponded to a 1% decrease in the odds of endometriosis. A gram increase in legume consumption resulted in a 3% decrease in the odds of endometriosis. Conversely, the intake of meat and fruit juice was associated with a 3% and 0.4% increase in the odds of endometriosis, respectively. Each unit increase in the consumption of sugar-sweetened beverages, trans fatty acids, and sodium was associated with increase in the odds of endometriosis.
Discussion of the AHEI Study
The results of this study suggest that adherence to the AHEI, characterized by high intakes of fruits, vegetables, and legumes, is associated with a lower likelihood of endometriosis. Conversely, higher intakes of meat, trans fatty acids, and sodium are associated with an increased risk of endometriosis.
Fertility Diet Score and Endometriosis
Another study investigated the association between the fertility diet score and the odds of endometriosis among Iranian women. The study found that women who adhered to the fertility diet had a lower odds of endometriosis. This was observed in both the base model and the adjusted model, with a significant decrease in odds of endometriosis by 66% and 54%, respectively. Additionally, consuming vegetable proteins and multivitamins were also associated with lower odds of endometriosis.
General Dietary Recommendations for Endometriosis
Based on the available evidence, several dietary recommendations can be made for women with endometriosis:
- Increase Fiber Intake: Consuming fiber may enhance the elimination of estrogen, potentially reducing the risk of endometriosis.
- Reduce Dietary Fat: Lowering the intake of dietary fat can decrease serum estrogen levels.
- Plant-Based Diets: Emphasize plant-based diets due to their anti-inflammatory nature and association with increased levels of sex-hormone binding globulin, reducing the amount of bio-available estrogen present in the body.
- Limit Red Meat: Meat intake is shown to be related to a higher risk of endometriosis.
- Anti-Inflammatory Diet: Following an anti-inflammatory diet is a viable option for managing endometriosis symptoms.
- Mediterranean Diet: The Mediterranean diet may have the most benefit without nutrition concerns. This diet primarily consists of abundant vegetables, fruits, legumes, seeds, nuts, and moderate amounts of dairy products and fish, with limited red meat and wine.
- MIND Diet: Adherence to the MIND diet, which is stricter about avoiding red meat, butter, fried foods, and sweets, may offer additional benefits.
- Increase Consumption of Specific Foods: Higher consumption of green leafy vegetables, other vegetables, nuts, legumes, berries, and fish are associated with a lower odds of endometriosis.
- Avoid Trans Fats and Limit Sodium: High intakes of trans fatty acids and sodium are associated with an increased risk of endometriosis.
The Gut Microbiota and Endometriosis
Emerging research suggests that the gut microbiota may play a role in endometriosis. The gut microbiota influences estrogen metabolism and immune function, both of which are implicated in the pathogenesis of endometriosis. Dietary interventions that promote a healthy gut microbiota, such as consuming probiotics and prebiotics, may be beneficial for women with endometriosis.
Traditional Chinese Medicine (TCM) and Endometriosis
Traditional Chinese Medicine (TCM) treats endometriosis as a symptom of underlying imbalance that can be treated with acupuncture, herbal therapy, and lifestyle changes. TCM aims to restore balance in the body and alleviate symptoms associated with endometriosis.
Additional Therapies for Endometriosis
In addition to dietary changes, other therapies may be beneficial for women with endometriosis:
- Massage Therapy: Massage can help to elevate mood, reduce stress, and release tight musculature that contributes to pelvic pain.
- Acupuncture: Acupuncture may help to reduce pain and improve overall well-being.
- Stress Management: Managing stress through techniques such as meditation and yoga may help to reduce inflammation and alleviate symptoms.
tags: #endometriosis #diet #and #fertility #research