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Cycle science: Diet, nutrition and reproductive health

By Maegan Boutot, Science Writer for Clue

The food you eat and your menstrual cycle have a complementary relationship. Your diet can affect how your reproductive system functions, while menstruation affects your need and use of micronutrients (i.e. vitamins and minerals).

Age at menarche

Age at menarche, or the age at which you start menstruating, is an important area of study because it’s strongly associated with breast cancer later in life (1, 2). The average age at menarche has decreased over the last fifty years (3), and researchers have suggested that one possible reason for this trend is dietary changes (4-8).

However, studies on the matter are not consistent. One study has linked fat, but not protein, to age at menarche (4), while another has found an association with protein, but not fat (5). Malnourishment may also affect these relationships (6). Furthermore, different types of protein, either from animal or plant sources, may have different relationships with age at menarche (7).

Consumption of sugary drinks, such as soda and fruit drinks, has also been linked to an earlier age at menarche (8). In one study, those who drank at least 1.5 sugar-sweetened beverages per day were more likely to start menstruating than those who drank less than two sugar-sweetened beverages per week (8). Fruit juice, as opposed to fruit drinks (such as Koolaid), was not associated with age at menarche, while fruit drinks and added sugar were associated (8).  

Caffeine and type of sweetener may play a role in this relationship (8, 9). A similar study in young girls found that caffeine and aspartame, an artificial sweetener, intake was associated with menarche before age 11 (9).

Scientists are still discussing the best way to do research on age at menarche and diet. For example, some studies have suggested that diet before age 7 may be more important than diet at ages 9 or 10 (7), and scientists are not sure how body mass index (BMI) affects the relationship between diet and menarche (7).

Premenstrual syndrome and calcium

Dietary factors have been repeatedly linked to premenstrual syndrome (PMS). For example, calcium intake is strongly associated with PMS (10-13). In those diagnosed with PMS, calcium supplementation has been shown to decrease the severity of symptoms, such as depression and fatigue (10, 11). Relatedly, one study has shown that those with high calcium intakes may be less likely to develop PMS (12). Calcium may help prevent and reduce symptoms of PMS because calcium affects normal cell behavior and serotonin development, the latter of which affects mood (13).

Calcium is also linked to vitamin D absorption (13), and high vitamin D levels have been associated with decreased risk of the development of PMS (12). Given that many people are deficient in either (or both) vitamin D or calcium (14-17), it is not always clear if the benefits of supplementation are due to fixing deficiencies or some other underlying mechanism. If you are interested in adding more calcium and vitamin D to your diet, consider consuming more dairy products, such as milk and cheese (12), or speak to your healthcare provider about calcium and vitamin D supplementation.

Menstruation and iron

It is possible for your cycle to affect the nutrient levels in your body. Specifically, menstruation lowers the amount of iron in your body (18). Iron is of particular concern for menstruating people as approximately 30% of premenstrual women are iron deficient (19), and the levels of iron deficiency are much higher in young females as compared to young males (20). Iron deficiency and iron deficiency anemia develop in menstruating people for many reasons. For example, those who experience heavy menstrual flow are at greater risk of iron deficiency, as are those with a vegetarian or vegan diet (19).

Vegetarians and vegans are at greater risk of iron deficiency due to the type of iron they consume (18, 21). There are two forms of dietary iron – heme (or haem) and non-heme (non-haem) (18, 19). Heme iron is found in meat and fish products, whereas non-heme iron is found in both plant and animal products (18, 21). Heme iron is more bioavailable than non-heme iron, meaning that your body can better use heme iron than non-heme (18, 21). This means that a person can consume the same amount of iron from food, but depending on the types of food, they may not have as much useable iron in their body (22). One study found that women placed on a high vegetable, low meat/fish diet had 32% less serum ferritin (a biomarker for iron in the blood) as compared to women placed on a high meat/fish diet after 20 weeks. These women consumed the same amount of iron but not the same type, which shows that iron levels in the blood are responsive to iron type, not just amount (22).

If you’re feeling tired, weak, and/or having trouble concentrating (19) during menstruation or otherwise, you may want to consider speaking with your healthcare provider to see if you are iron deficient. To help prevent iron deficiency during menstruation, consider adding more meat and fish, particularly red meat, to your diet during your period (18). If you are vegetarian, vegan, or otherwise unable to eat meat or fish, consider speaking with a healthcare provider about alternative dietary approaches, such as adjusting your calcium, soy and vitamin C levels during your period, to help manage a potential iron deficiency (23).

Unsure if you feel more tired or weak during your period and need to adjust your diet? Download Clue today to start tracking your cycle.

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