I learned this the other day, that I was iron deficient but although I increased my iron intake I was still lethargic and just plain ill. Well I learned that its the foods that we are combining with our supplements affect the body's absorption of iron. For example grains, eggs, beets , coffee and teas inhibit the absorption of non heme iron. So since I am a coffee addict, tea drinker, brown rice eater and I juice beets constantly my body was not holding on to the non-heme iron which my body needed.
But Vitamin C combined with non-heme iron will help your body to absorb it. So if your diet is plant based add Vitamin C rich vegetables or fruits . Or combine the supplements so if you are taking your iron supplement take your vitamin C supplement at the same time . This has helped me immensely .
Please consult with your doctor .