>I've heard that the oxalic acid in greens such as spinach interfere with
>calcium absorption in foods such as sesame seeds. Any opinions?
        I know that in the case of spinach (one of my favorite things to
eat!) that the HIGH iron content of the food DOES slow down if not all
together prevent the digestion of calcium.  This same principal works for
vitamin supplements. Most women's formulas, for example, are high in BOTH
calcium and iron.  The two more or less cancel each other out and your not
as protected as you might think you are by taking a multi-vitamin. Also many
forms of calcium supplements are not bio-available. Another, often over
looked point is the importance of regular weigh baring exercise to aid in
strengthening bones.  Even a walking program can help keep bones stronger.
        If you want a quick source for up to date info on nutrition you may
want to try to contact that American Dietetic Association (ADA--not to be
confused with the dairy ADA).  They have a web site at:
http://www.eatright.org/ and are a good source of education on nutritional
matters--but naturally their web site is VERY general. Their "gateway to
nutrition" is a huge resource of links to various organizations of interest.
You may also be interested in contacting a nutritionist to seek personalized
help and they have links for that info as well (though I haven't had to try
that avenue--my local health insurance plan includes such nutritional
consultations in my health care.)  But what I can say from experience is
that it is possible, even for a pregnant vegan, to get enough calcium from
diet alone.