Medical studies on long-term RNY malabsorption of calories?

OK, so one of the things that surgeons do not seem to agree on is whether the caloric (and fat) malabsorption of RNY is permanent (yet they all agree that the vitamin malabsorption is permanent).

Has anyone seen any medical studies or research on this?

Lora

I don't know of any studies that are specific to RNY ... But do some digging on 'adaptation after bowel resection' in cancer patients. That's where the data lies.

yes we will lose the malabsorption of macronutrients over time. But we will always malabsorb miconutrients.

posting from my phone... Can get you links later.

Thanks, Pam!  You are an amazing source of info as usual!  I used your search suggestion and easily found the following (once I eliminated studies only on rats, dogs, etc., LOL). 

Even though RNYers do not quite qualify for "short bowel syndrome" (we don't have quite enough of the intestine bypassed), the  physiology would be the same.  Here is what the article says about the adaptation (that up to 90% of the malabsorption is overcome in 12-18 months (phase two), for those of you not inclined to wade through the "med-speak").  The extra numbers in the text are footnotes that I am too lazy to take out...  Note the reason for RNYers being encouraged to drink, drink. drink during the first few months (phase one)!

http://emedicine.medscape.com/article/193391-overview

"Macronutrients and micronutrients are absorbed along the length of the small intestine. However, as described by Clarke, the jejunum has taller villi, deeper crypts, and greater enzyme activity compared to the ileum.11 Therefore, under normal conditions, about 90% of digestion and absorption of significant macronutrients and micronutrients are accomplished in the proximal 100-150 cm of the jejunum according to work conducted by Borgstrom and colleagues and by Johansson.12,13 This includes absorption of proteins; carbohydrates; fats; vitamins B, C, and folic acid; and the fat-soluble vitamins A, D, E, and K.

However, if a significant portion or all of the jejunum is resected, the absorption of proteins, carbohydrates, and most vitamins and minerals can be unaffected because of adaptation in the ileum.

The physiologic changes and adaptation of patients with short-bowel syndrome can be viewed in 3 phases.16  
 
The acute phase occurs immediately after massive bowel resection and may last up to 3-4 months. The acute phase is associated with malnutrition and fluid and electrolyte loss through the gastrointestinal tract. Fluid and electrolyte loss through the gastrointestinal tract may be as high as 6-8 L/d. Patients will have abnormal liver function test results and transient hyperbilirubinemia. Enteral feedings may also be initiated, but it should be relatively slow. Patients with less than 100 cm of small intestine will require total parenteral nutrition. The presence of ileocecal valve or colon may play a significant role in the outcome of these patients.16 
 
The adaptation phase generally begins 2-4 days after bowel resection and may last up to 12-18 months.16  During this second phase, up to 90% of the bowel adaptation may occur. Villous hyperplasia, increased crypt depth, and intestinal dilatation occur. Early continuous feedings with a high viscosity elemental diet may reduce the duration of total parenteral nutrition.16
 
In the maintenance phase, the absorptive capacity of the gastrointestinal tract is at its maximum.16  Some patients may still require total parenteral nutrition. In other patients, nutritional and metabolic homeostasis can be achieved by small meals and supplemental nutritional support for life. These patients will also require vitamins and mineral supplements, including vitamins A, B-12, and D, magnesium, and zinc.16"

Lora
 

Great info, thanks for doing the research, Lora!

Thanks, very interesting.

This explains the dreaded 10-15% weight regain with no change in eating habits unfortunately. I was aware of this since my dad was a surgeon, so at 18 months I started being hyper-vigilant. Does anyone know if this explains why hunger comes back so terribly?

****ro:  Actually, the current thought is that there is insignificant malabsorption of macronutrients (fat, protein, carbs) after RNY.  We don't have enough small bowel removed to extrapolate to the short bowel studies.

Here is an interesting text book for bariatric physicians from 5 years ago which explains this.  You can actually read it on Goole.com.  Go to page 80 and start reading at "Nutrient Absorption and Deficiencies" and read through page 82.

books.google.com/books

I then did a medical literature search and could find no studies to add anything to this knowledge in the past 6 years in the medical journals.  So it still seems to be more of a restrictive procedure (along with less ghrelin hormone, etc.) as the main cause of weight loss rather than macronutrient malabsorption.

It's been a long day, and I am quite tired, so I will not quibble about whether we have "enough" of a bypass that the same physiological processes are in place as with short bowel syndrome (although I see no reason that ANY length of intestinal removal would not precipitate the same response by the body).

I do not, however, see anything in what you posted that contradicts what I found and posted...  which was that there is no permanent malabsorption of calories for RNY folks... that the malabsorption of calories in RNY is quite temporary and by the time you are a year out you are relying on the restriction only.

Lora

Yep, I agree.  Sorry, didn't mean to offend, I was just answering your question about latest medical information regarding RNY and absorption... so that was the best I could find.

No problem.  As I said, it's been a long, taxing day so perhaps I read something into your original post that was not there.

At least we are finding the same info.  (I found two other articles that indicated much the same... if you want long-term malabsorption, you have to go the DS route.)

Lora