Question:
How is it that we can absorb some things and not others?

I am 4 weeks post-op and this question has baffled me. How is it that we can take vitamins and they are absorbed, but some say birth control is not? My Doctor said that birth control is absorbed and I can still take it and it will be effective. But there have been conflicting messages and I was wondering if anyone knew how this works....Thanks!    — Denise D. (posted on July 29, 2003)

July 29, 2003
It's not that we don't absorb what we take in, it's that we don't absorb all of it. That's why we take two vitamins a day, when one has 100% of the daily requirement, and two or three calcium supplements. We absorb some of each dose, but not all. Between all the doses, we end up with an adequate amount. If your PC is not very knowledgeable about WLS, I wouldn't trust the comment that we absorb birth control pills. We absorb some of it, but not all. Some of us absorb enough for it still to be effective, but some don't. That's why a fair number of women who were on birth control pills end up pregnant before their first year, and before they wanted to be. My PCP, while a great general doc, doesn't have any experience with other WLS patients (I'm his only one). He, too, thought I'd be OK on birth control pills. While I haven't gotten pregnant, my periods have changed to where I was getting them earlier and earlier. Before surgery, I always started my periods on the Wednesday following the last pill. Shortly after surgery, I would start on the Monday, then the Sunday. Then one started before I finished the monthly pack. So I know they're not being fully absorbed. We're using an alternate form of birth control until I lose another 20 pounds and can go on the patch. Be careful.
   — Vespa R.

July 29, 2003
I've heard that you only absorb 85% of the pill. I believe it's directly in relation to what part of our intestine is designed to absorb what substance. For example we have issues with calcium absorption because they've bypassed the part of the intestine where calcium is absorbed. However, we have no trouble absorbing sugar because the part of the intestine where we absorb sugar is still intact. I really should know the answer to this for certain but I'm just making a guess. When it comes to pregnancy, however, I wouldn't take any chances. I'd use a "for certain" method of birth control. Best wishes to you!
   — ronascott

July 29, 2003
Well, the answer to your question is two-fold. First you have the roux-en-Y gastric bypass, in which you bypass the bulk of the stomach (and its acid) and connect back to the intestine after the duodenum (which is also very acidic and stays attached to the "exit" of the stomach) to form a Y shape. Think of the intestine as a gradient, going from most acidic (in the stomach--ever had heartburn??? you know what I'm talking about, then!) to least acidic at the "end of the line" (thank heavens for small favors!). Anything that requires a high concentration of acid to be absorbed (calcium carbonate, B-12, etc.) will not be absorbed well by RNY patients. But proximal RNY patients still have MOST of their intestines intact and so have plenty of opportunity to absorb anything else. My dr says that proximal patients lose their weight due to RESTRICTION (eating smaller amounts) rather than MALABSORPTION (not absorbing the food you eat).<p>So here is the second part. If you've had a distal RNY, not only has the most acidic portion of your gastric system been bypassed, but also a considerable amount of the intestine that is left intact in a proximal RNY. So not only will you lose weight from restriction but also from malabsorption. In this case, you will NOT absorb 100% of what you eat, no matter whether it needs acid to be absorbed or not. So while it does help them lose more weight, distal RNYers have to be more conscientious of their diets to avoid becoming malnourished.<p>I hope this helps. Absorption is a complex issue and I wish they would do more research so we would have some concrete guidelines to go by. As it is, you just have to use common sense: Use calcium citrate and sublingual or subcutaneous B-12 so that you know it will be absorbed, and hedge your bets on your protein consumption.<p>As far as the BCP is concerned, I haven't seen any studies one way or the other but if you really really don't wanna get pregnant, I'd use a backup method!
   — ctyst

July 29, 2003
My surgeon told me to use TWO forms of birth control for the first 18 months after surgery. If you take the pill, use a condom as well, etc. Just my 2 cents. :)
   — Cheryl M.