With International Women’s day in March, and in celebration of women, I wanted to take a closer look at nutrition for women. Although a healthy and balanced diet is essential for both men and women, women have different nutritional requirements than men. Of course, all nutrients are important, but here is a list of some nutrients women should pay attention to.

Remember, nutrient recommendations are a guideline, not a target. This is because everyone is different and individual needs vary in size and activity levels.

Iron

Iron is crucial for making red blood cells, which carry oxygen from our lungs around the body. It also helps the immune system work properly, can help improve brain function and reduce tiredness.

Low iron means we can’t produce enough red blood cells to supply oxygen around the body. This can lead to anaemia - a low number of red blood cells - which can include symptoms like fatigue, weakness, paleness, dizziness, lack of focus and hair loss. Iron deficiency is the most common nutritional deficiency globally; over a quarter of women may have an inadequate iron intake.

Premenopausal women - from the onset of menstruation to menopause - need 16mg of iron per day, including during pregnancy and lactation. This is higher than for men and women past menopause - 11mg of iron per day - as during menstruation - a monthly period - iron is lost with the blood and can use up iron reserves, especially if monthly periods are heavy or our diet is low in iron.

Sources of iron include meat, fish, shellfish, pulses & legumes - beans, chickpeas, lentils - wholewheat, nuts, dried fruits, tofu and dark green vegetables - broccoli, spinach & kale.

Iron from plant foods is less readily absorbed than from animal foods. To increase iron absorption, try pairing it with food rich in vitamin C - e.g. bell peppers, cauliflower, peppers, kiwi, or citrus fruits - and avoid tea and coffee during meal times as their tannins and polyphenols can reduce iron absorption.

Calcium

Calcium is important for building and maintaining strong, healthy bones and teeth. 99% of the calcium in our body is stored in our bones and teeth, so if we aren’t getting enough calcium from food, our body will take it from our bones. Calcium is also used for muscle contraction - including the heart - and ensuring our blood clots normally.

A lack of calcium in adults can lead to osteomalacia -  a softening of the bones -  or osteoporosis -  weakening of the bones - which increases the risk of bone fractures.

Premenopausal women need 1000mg of calcium per day, including during pregnancy and lactation. Women during and post menopause need a higher intake of calcium, 1200mg per day, this is because our body slowly loses bone mass with the loss of estrogen production.

Sources of calcium include dairy products - milk, yoghurt, cheese - tofu, legumes - white bean, edamame, chickpeas - canned salmon and sardines, nuts, fortified plant-based dairy alternatives, okra, dark leafy green vegetables -kale, broccoli, spinach, bok choy - and dried fruits - figs & apricots.

Vitamin D

Vitamin D is key to helping balance levels of calcium in our body as it helps absorb calcium from food and release calcium from bones when needed. So vitamin D is also just as important for healthy bones and teeth. It also supports the healthy function of our immune system. Interestingly, vitamin D is the only nutrient where the main source is not from the diet, but from sunlight exposure.

For healthy adults, including during pregnancy and lactation, an adequate intake of vitamin D is 15 micrograms (μg) or 600 international units (iu) per day. 

There are many factors that can influence our ability to make vitamin D, such as low sun exposure, skin pigmentation, clothing and ageing. In some cases, supplementation may be needed, and it is often recommended for people in the northern hemisphere to consider supplementation of 10 μg or 400 iu per day during the autumn and winter months due to low sunlight exposure.

Sources of vitamin D include sunlight, oily fish - salmon, herring, mackerel & sardines - egg yolk, lean red meat, fortified foods and drinks - fat spreads, dairy alternatives or cereals - and mushrooms exposed to sunlight or UV light.

Folate - Folic Acid

Folate - often referred to as folic acid in supplementation or vitamin B9 - is important for forming healthy red blood cells and DNA for new cells. It is a key player in the healthy development of babies during pregnancy, supporting skull, brain and spinal cord development and reducing the risk of babies developing neural tube defects - e.g. spina bifida. 

Healthy adults need 330 μg of dietary folate equivalents a day. Folate requirements increase during pregnancy and lactation; it is recommended to increase folate intake before becoming pregnant. Before and during the first 3 months - 12 weeks - of pregnancy it is advised to eat folate-rich foods and supplement with 400 μg (0.4 mg) of folic acid per day. During lactation, folate intake should be 500 μg of dietary folate equivalents a day to cover folate losses via breastmilk.

Sources of folate include dark leafy green vegetables - spinach, kale, cabbage and spring green - broccoli, brussels sprouts, okra, beans and legumes - peas, chickpeas, kidney beans & black-eyed beans - orange and grapefruit juice, wholegrains, nuts and fortified breakfast cereals.

Keep in mind, folate is a water-soluble vitamin, meaning it dissolves in water and is lost from vegetables during cooking. To reduce this loss, it’s better to steam or microwave vegetables instead of boiling them and avoid over-cooking.

Omega-3 Fatty Acids

Omega-3 fatty acids are important for our health as they have an anti-inflammatory effect and protect our heart.

Omega-3 fatty acids are especially important for pregnancy as they are essential for normal brain development, particularly during the last trimester of pregnancy when the baby’s brain develops the fastest. It’s important to have a good intake of omega-3 fatty acids for pregnancy as it helps ensure that women’s adipose tissue - body fat - contains a supply of these fatty acids for the developing foetus and the breastfed newborn infant.

Omega-3 fatty acids may also play a positive role in preventing menstrual syndrome and postmenopausal hot flushes.

It is recommended to have 250mg a day of EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) - 2 types of omega-3 fatty acids. Pregnant women should increase their intake of DHA by supplementing with 100-200mg of DHA a day, in addition to the 1-2 servings of seafood - particularly oily fish - recommended to the general population. Women who are pregnant should not consume more than 2 portions of oily fish a week.

Sources of omega-3s include oily fish - salmon, trout & mackerel - shellfish, soy and soy products - tofu, beans & milk - chia seeds, flax seeds, almonds, walnuts, soybeans, and vegetable oils - rapeseed & linseed oils.

Iodine

Iodine is a mineral which is mostly stored in our thyroid gland - found in the front of our neck - and crucial in thyroid hormone production. These hormones affect our growth and metabolism - e.g. producing energy or regulating our temperature. Thyroid hormones are important during pregnancy as they contribute to normal growth and development, including the baby’s brain and nervous system.

Healthy adults need 150 μg of iodine a day. During pregnancy and lactation, iodine needs can go up to 200 μg per day to ensure the mother's thyroid creates and transfers enough thyroid hormones to support the development of the baby’s brain and that breastmilk contains enough iodine to continue supporting the infant's brain development. Iodine is needed from the very early stages of pregnancy, therefore it is important to ensure the body has good stores of iodine in the thyroid before pregnancy.

Sources of iodine include seafood - fish, shellfish, molluscs & seaweed - milk and dairy products, eggs, fortified foods such as dairy alternatives, nuts, cereals and grains.

Iodine levels will vary in plant foods depending on the amount of iodine available in the soil where they are grown. Some countries also add iodine to salt - iodised salt - which can be a good alternative to regular salt, however, we should be mindful of the amount of salt in our diet and prioritise other sources of iodine.

What’s the take-home?

1. There are some nutrients women should pay attention to such as iron, calcium, vitamin D, folate, omega-3 fatty acids, and iodine.

2. Premenopausal women need more iron due to the loss of iron during menstruation.

3. During and post-menopause, calcium and vitamin D intakes are important for women due to the body slowly losing bone mass with the loss of estrogen production.

4. Some nutrients need to be increased before, during, or after pregnancy if breastfeeding, these include folate, omega-3 fatty acids and iodine due to their link with the baby’s brain development.

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References

1. British Nutrition Foundation. Healthy Sustainable Diets - Vitamins and Minerals. 2021. Retrieved February 23, 2023, from https://www.nutrition.org.uk/healthy-sustainable-diets/vitamins-and-minerals/ 

2. National Health Service (NHS). Vitamins and Minerals. Retrieved February 23, 2023, from https://www.nhs.uk/conditions/vitamins-and-minerals/ 

3. World Health Organization (WHO). Vitamin and mineral requirements in human nutrition. 2nd edition. 2004. Geneva, Switzerland: WHO.

4. British Nutrition Foundation. Nutrition recommendations for women. 2018. February 23, 2023, from  https://www.nutrition.org.uk/life-stages/women/nutrition-recommendations-for-women/ 

5. European Food Safety Authority (EFSA). Scientific Opinion on Dietary Reference Values for Iron. EFSA Journal 2015;13(10):4254. Available from: https://efsa.onlinelibrary.wiley.com/doi/epdf/10.2903/j.efsa.2015.4254 

6. European Food Safety Authority (EFSA). Scientific Opinion on Dietary Reference Values for Calcium. EFSA Journal 2015;13(5):4101. Available from: https://efsa.onlinelibrary.wiley.com/doi/epdf/10.2903/j.efsa.2015.4101

7. European Food Safety Authority. Scientific opinion on dietary reference values for vitamin D. EFSA Journal 2016;14(10):4547. Available from: https://www.efsa.europa.eu/en/efsajournal/pub/4547 

8. European Food Safety Authority. Scientific opinion on dietary reference values for folate. EFSA Journal 2016;12(11):3893. Available from: https://www.efsa.europa.eu/en/efsajournal/pub/3893 

9. European Commission. Folic Acid and Neural Tube Defect. Available from: https://eu-rd-platform.jrc.ec.europa.eu/eurocat/prevention-and-risk-factors/folic-acid-neural-tube-defects_en#:~:text=Folic%20Acid%20is%20a%20synthetic,first%20three%20months%20of%20pregnancy. 

10. European Food Safety Authority. Dietary reference values for nutrients - Summary report. EFSA Supporting Publications. Available from: https://www.efsa.europa.eu/sites/default/files/2017_09_DRVs_summary_report.pdf

11. Bourre JM. Dietary omega-3 fatty acids for women. Biomed Pharmacother. 2007 Feb-Apr;61(2-3):105-12. doi: 10.1016/j.biopha.2006.09.015.

12. European Food Safety Authority. Scientific opinion on dietary reference values for iodine. EFSA Journal 2014;12(5):3660. Available from: https://www.efsa.europa.eu/en/efsajournal/pub/3660