The Nutrient Cost of Menstruation
Every menstrual cycle involves blood loss that depletes iron. Women of reproductive age need approximately twice the daily iron intake of men (18mg vs 8mg), yet most dietary guidelines are designed around male reference standards. Iron deficiency without anaemia, a much earlier stage, causes fatigue, reduced exercise performance, brain fog, and worsened PMS symptoms that are rarely attributed to iron status.
Iron: Sources and Absorption
Haem iron from animal sources (red meat, liver, shellfish) is absorbed at 15–35% efficiency. Non-haem iron from plant sources (lentils, tofu, dark leafy greens, fortified cereals) absorbs at 2–20% but this can be significantly improved by eating it with vitamin C and avoiding tea or coffee within an hour. If you have heavy periods and persistent fatigue, ask for a serum ferritin test, not just haemoglobin, as ferritin depletes earlier.
Magnesium for PMS and Period Pain
Magnesium is involved in over 300 enzymatic reactions and plays a specific role in reducing period pain (by relaxing smooth muscle), improving sleep in the luteal phase, and reducing anxiety. Dietary sources include dark chocolate, pumpkin seeds, spinach, almonds, and avocado. Supplemental magnesium glycinate (300–400mg daily) has the strongest clinical evidence for PMS symptom reduction, consistently outperforming placebo in randomised controlled trials.
Omega-3s and Prostaglandins
Period cramps are driven by prostaglandins, inflammatory compounds that cause uterine muscle contractions. Omega-3 fatty acids (EPA and DHA from oily fish, algae, or supplements) compete with the omega-6 arachidonic acid pathway, reducing the production of pro-inflammatory prostaglandins. Studies show that fish oil supplementation reduces period pain comparably to ibuprofen in some women, with a better long-term safety profile.
Medical Disclaimer
This article is written for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before making health decisions.
Claire Thompson
RD, MSc Nutrition
All TryHerCare articles are written and reviewed by qualified medical professionals. Our content is clinician-reviewed to ensure accuracy and clinical relevance.
