A vegan or exclusively plant-based diet can make periods lighter and less painful but it can also cause irregular periods due to impaired ovulation and low progesterone.
The problem is not that phytoestrogens cause high estrogen. In fact, phytoestrogens have a generally anti-estrogen, period-lightening effect. The main problem with a vegan diet is that is can cause long-term depletion of important women’s health nutrients such as zinc, iodine, vitamin A, and taurine.
The following are my observations based on 25 years with patients. If you’ve been vegan for more than a year, I encourage you to share your experience 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 can be attributed 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 but 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 make periods lighter
The phytoestrogens in grains, seeds, and legumes (especially soy) can make periods lighter and lengthen the follicular phase. Why? Because they are weaker than own stronger estrogen (estradiol), and so shelter us from estrogen.
Phytoestrogens are essentially “anti-estrogen,” which in moderation, is a good thing.
In excess (as might occur with an exclusively plant-based diet), phytoestrogens can lengthen cycles, reduce progesterone, or in some cases, suppress ovulation altogether.
From the comments: A few of you mentioned heavier periods on a vegan diet, which I attribute to low progesterone or a deficiency of zinc, iron, vitamin A, and/or iodine.
Nutrient deficiencies from a vegan or plant-based diet
An exclusively plant-based diet can deplete nutrients. 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
- heme iron
- EPA and DHA omega 3 fatty acids
- vitamin D3
- vitamin K2 (MK-4 subtype)
Nutrients that are low in plant foods:
- coenzyme Q10
- active vitamin B6 (pyridoxal-5-phosphate)
- vitamin B2 (riboflavin)
It can take at least a year to deplete reserves of nutrients such as vitamin A, a make-or-break nutrient for period health. Having the more active form of the enzyme (encoded by the BCMO1 gene) that converts beta carotene to vitamin A is why some women can stay relatively healthy on a plant-based diet.
👉 Tip: Bumpy skin on the back of the arms (keratosis pilaris) is a sign of vitamin A deficiency.
Zinc is depleted more quickly than vitamin A and zinc deficiency can impair ovulation and cause 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.
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.