A woman with heavy menstrual bleeding, SlimPhoria Keto You may need an iron supplement to replace iron from blood loss. To enhance absorption, take iron supplements with water or juice on an empty stomach. If nausea or constipation are problems, take iron supplements with food. Absorption may be decreased by as much as 50 percent when taken with a meal or a snack. A woman who's pregnant or breast feeding. You need more of some nutrients, especially folate and iron-and perhaps calcium if you don't consume enough calcium-rich foods. Check the label's Supplement Facts to make sure you get enough for a healthy pregnancy. Ask about a prenatal vitamin/mineral supplement.