A vegan or exclusively plant-based diet can make periods lighter and less painful, which is good. Over time, however, a plant-based diet can cause irregular or heavy periods due to impaired ovulation and low progesterone.
Phytoestrogens are a factor but the main problem with an exclusively plant-based diet is that it cannot provide an adequate supply of nutrients such as zinc, iodine, iron, vitamin A, and taurine.
The following are my observations based on 25 years with patients. If you’ve been on an exclusively plant-based diet for at least a year, please join the conversation in the comments.
Going off dairy can be good for periods
A vegan diet can make periods lighter and less painful and most of that benefit is due to stopping cow’s dairy. Dairy typically makes periods heavier and more painful because A1 casein can cause a mast cell and histamine response. Dairy and gluten (and sometimes eggs) can also worsen endometriosis.
The fact that cow’s dairy (and sometimes eggs) are bad for endometriosis does not mean that all animal protein is bad for endometriosis or that eggs are bad for periods in general.
👉 Tip: A2 dairy such as goat and sheep dairy is usually fine for periods.
Phytoestrogens can make periods lighter
The phytoestrogens in grains, seeds, and legumes have a beneficial anti-estrogen effect. That’s why (in moderation), phytoestrogens can make periods lighter and lengthen the follicular phase. In excess, phytoestrogens can potentially impair ovulation and progesterone and even shut down periods.
A vegan or plant-based diet causes multiple nutrient deficiencies that affect periods
The main problem with a vegan diet is nutrient deficiency. According to registered dietitian Valeria Burnazov, the following nutrients are either missing or low in plant foods.
Nutrients that are not present in plant foods:
- preformed vitamin A
- vitamin B12
- taurine (read 5 Benefits of taurine for women’s health)
- heme iron
- EPA and DHA omega 3 fatty acids
- vitamin D3
- vitamin K2 (MK-4 subtype)
Nutrients that are low in plant foods:
- zinc (read Why zinc is my favourite supplement for period health)
- iodine (read Why I prescribe iodine for breast pain, ovarian cysts, and PMS)
- coenzyme Q10
- active vitamin B6 (pyridoxal-5-phosphate)
- vitamin B2 (riboflavin)
Deficiency of iron, zinc, iodine, and/or vitamin A can impair ovulation and cause amenorrhea (lack of periods), anovulation (irregular periods), or heavy periods due to low progesterone.
Zinc can deplete rapidly on a plant-based diet and cause irregular periods and skin problems.
👉 Tip: If you’re vegan and having trouble with your periods, you could try what I call an “ovulation cocktail for vegans,” which is zinc plus iodine to support ovarian function.
Vitamin A takes longer to deplete because it is stored by the body but eventually, vitamin A deficiency can contribute to skin problems, heavy periods, and endometriosis. Plant-based beta-carotene and other carotenoids convert to vitamin A but only if you have an active genetic variant of the enzyme beta-carotene oxygenase-1 (BCO1 or BCMO1) and a sufficient level of zinc, which is a co-factor for the enzyme.
👉 Tip: Bumpy skin on the back of the arms (keratosis pilaris) is a sign of vitamin A deficiency.
Nutrient deficiencies are less likely to occur with a vegetarian or partly plant-based diet. Even a moderate amount of nutrient-dense animal food such as goat cheese and eggs can make a huge difference to periods.