Little is known about the impact of diet on the risk and growth of uterine fibroids (leiomyomas). This is not surprising as nutrition research is underfunded, Women’s health is underfunded and fibroids disproportionately affect women of color. A simple PubMed search on diet and fibroids lists 4 review articles from 2021 on diet/nutrition in gynecologic or reproductive diseases all lumped together, as if fibroids and endometriosis and PCOS were all one disease. That’s the state of things. Nonetheless I will try my best to summarize the impact of nutrition on fibroids.
Fruit and vegetable consumption is associated with a reduced risk of developing fibroids in the 3 largest epidemiologic studies in African-American, Italian and Chinese women. Antioxidant micronutrients like Vitamin C and beta-carotene have anti-inflammatory roles. Specific phytonutrients like lycopene from tomatoes and indole-3-carbinol from Brassica vegetables have been shown in animal studies and cell studies to inhibit leiomyoma (aka fibroid) cell growth. Strawberry extract has been shown to induce cell death in fibroid cells. The potent antioxidant found in grapes and wine called resveratrol has been shown to suppress growth of leiomyoma cells. Not surprising is the recommendation to eat more fruits and vegetables.
Vitamin D is the most widely studied and reported nutrient in people with fibroids. Vitamin D deficiency has been associated with more numerous and larger fibroids across multiple populations and correcting deficiency may reduce the need for surgical interventions. Vitamin D can be obtained through dairy foods, sunlight or supplementation. High doses beyond what is needed to correct or prevent deficiency have not shown to be useful.
Vitamin A intake has been shown in large population studies to be associated with a reduced risk for fibroids. Cell studies and animal models have shown that Vitamin A reduced growth of fibroid cells. Good sources of Vitamin A are fish, liver, eggs and plant sources are foods that contain beta-carotene like carrots, winter squash and sweet potatoes.
Surprisingly, dairy has been shown to reduce the risks of fibroids in Black women but increase the risk of fibroids in Chinese women. Calcium and a fatty acid called butyric acid that is present in dairy fat may explain the protective effect in Black women. If you are lactose intolerant, fermented or cultured dairy like yogurt and cheese are naturally lower in lactose than milk, and lactose free milk does exist.
Animal protein sources may impact fibroid risk and growth. Red meat and ham were associated with more fibroids in an Italian population but not in a Chinese population. Omega-3 fats like the ones found in fish were found to be protective in some studies but other studies showed that fish consumption increased fibroid risk. This may be due to toxic chemicals in fish and not the fat content. This underlies the importance of having a safe food supply and that contaminants consumed in food may have more of an impact than nutrients in food. Choose fish that are both high in omega-3 but low in contaminants like wild Atlantic salmon, Pacific sardines, cod, farmed rainbow trout, anchovies.
Environmental toxins and food contaminants play a large role in the development of fibroids. Avoiding these chemicals which have been termed “endocrine disruptors” maybe more important than making the changes described above. Endocrine disruptors can act as hormones and also interfere with nutrient metabolism; even if you get enough nutrients, they may not be able to function properly.
The differences in how foods affect fibroids in various populations may be explained by a relatively new area of study called metabolomics. There are different mutations that cause fibroids in different populations that also result in differences in the ways nutrients are metabolized by those cells. A better understanding of these small changes in metabolism may give us a better understanding of what causes fibroids and help us create new and better treatments. The mutations present in a group of people may be due to environmental exposures in a particular region or due to inherited mutations particular to an ethnic group.
If you have anemia caused by fibroids, iron is important. Iron from animal proteins is more readily absorbed although vegetarian sources do exist in nuts, dried fruit, beans and cooked leafy greens.
Soy is controversial, Soy isoflavones act as a weak estrogen, binding to estrogen receptors. Some studies show that early soy intake (when circulating estrogen levels are low) increases risk for developing fibroids but consumption after puberty (when levels are higher) may be protective. Also smaller soy doses may protect against fibroids and higher doses may be detrimental.
Lastly sugar stimulates insulin like growth factor (IGF-1) which turns on growth of fibroid cells. IGF-1 also stimulates estrogen and progesterone production which may cause fibroids to grow. Even though we do not know what the best diet is for women with fibroids or at risk for fibroids it is safe to say increasing fruit and vegetable intake, and reducing sugar intake is a good idea. Getting enough Vitamins D and A is very important. Dairy may be beneficial if you are of African descent. Fish high in omega-3 fatty acids may be of benefit but only if it is a low contaminant species. It is obvious that more research is needed to determine the foods that have the most impact on fibroids, and learning how nutrients are metabolized by fibroid cells may lead the way towards new treatments. Diet alone will not treat your fibroids, but improved nutrition may slow growth or prevent them if you are at high risk.