Rankings of iron, vitamin D and calcium intakes in relation to maternal characteristics of pregnant Canadian women (Lay summary)

Morisset AS, Weiler HA, Dubois L, Ashley-Martin J, Shapiro GD, Dodds L, Massarelli I, Vigneault M, Arbuckle TE, Fraser WD, MIREC Study Group. Applied Physiology, Nutrition and Metabolism. Jul;41(7):749-57. doi: 10.1139/apnm-2015-0588. 

Good nutrition is very important determinant of maternal and infant health.  Iron, vitamin D, and calcium are essential nutrients that are involved in a number of the body’s physiological processes. For example, iron is a key component of red blood cells, while vitamin D and calcium are central to bone formation and maintenance. For healthy individuals eating a balanced diet, these nutrients are usually obtained from certain foods we eat. People who are deficient in one or more essential nutrients due to an unbalanced diet can obtain them by taking supplements.

To gain a better understanding of essential nutrient intake during pregnancy, this study examined iron, vitamin D and calcium intakes from the diet and from supplements, and how these intakes may vary with different maternal characteristics.

Researchers used data from 1,186 mothers enrolled in the Maternal-Infant Research on Environmental Chemicals (MIREC) Study. They estimated maternal dietary intakes of iron, vitamin D and calcium using a food frequency questionnaire (at 16-21 weeks of pregnancy) and additional questions on dietary supplements.

This study found that supplement intake was a major contributor to total iron and vitamin D intake, but not for calcium intake.  Interestingly, women born outside of Canada had lower total intakes of iron, vitamin D and calcium, while women with a higher level of education (holding a university degree), or older than 30 years of age were more likely to take supplements.

These findings suggest that the probability of having lower iron, vitamin D and calcium intake is greater among women born outside Canada.  From a clinical viewpoint, professional health care providers may pay particular attention to pregnant women who are not taking iron and vitamin D supplements, since these are important contributors to total intakes of these essential nutrients.  During pregnancy, the need for iron is higher, which places women at greater risk of deficiency. This is why Health Canada recommends that women should take a daily supplement containing 16 to 20 mg of iron during pregnancy (https://www.canada.ca/en/health-canada/services/food-nutrition/reports-publications/nutrition-healthy-eating/prenatal-nutrition-guidelines-health-professionals-iron-contributes-healthy-pregnancy-2009.html).