McKinley Health Center – Dietary Sources of Iron – University of Illinois:

“The Recommended Dietary Allowance (RDA) for
iron for non-vegetarian pre-menopausal women is 18 mg/day. The RDA for
non-vegetarian men and post-menopausal women is 8 mg/day. Because of iron
absorption issues in a healthful, high-fiber vegetarian diet, the RDAs for
vegetarians are higher – 14 mg/day for vegetarian men and 33 mg/day for
vegetarian women. The upper level of intake should not exceed 45mg/day.”

Lack of iron causes stomach aches. Iron needs to be taken at lunch not at bedtime with calcium.