RNY = Minimal Fat Malabsorption vs MGB = Major Fat Malabsorption

Malabsorption following the Roux-en-Y gastric bypass

What is Roux-en-Y Gastric Bypass?

• Roux-en-Y Gastric Bypass both (?)

• Restrictive

• Malabsorptive (?)Components

Malabsorption vs. Restriction after long-limb RNY gastric bypass

• Roux-en-Y gastric bypass (RNY) restricts food intake

• when the Roux limb is elongated to 150 cm

• IS the RNY malabsorptive?• Measure calorie reduction after RNY• Restriction vs Malabsorption• The contribution of malabsorption to the reduction in net energy absorption after long-limb Roux-en-Y gastric

bypass, Elizabeth A Odstrcil, et al. Am J Clin Nutr October 2010 vol. 92 no. 4 704-7

“The contribution of malabsorption to the reduction in

net energy absorption after long-limb

Roux-en-Y gastric bypass”

Elizabeth A Odstrcil, Juan G Martinez, Carol A Santa Ana, Beiqi Xue, Reva E Schneider, Karen J Steffer, Jack L

Porter, John Asplin, Joseph A Kuhn, and John S FordtranAm J Clin Nutr October 2010 vol. 92 no. 4 704-713

The contribution of malabsorption to the reduction in net energy absorption after long-limb Roux-en-Y gastric bypass

• Results:• RNY:• No significant effect on • Protein or Carbohydrate

absorption

• “The contribution of malabsorption to the reduction in net energy absorption after long-limb Roux-en-Y gastric bypass”, Elizabeth A Odstrcil, et al. Am J Clin Nutr October 2010 vol. 92 no. 4 704-713

RNY Malabsorption vs. Restriction

• 5 months after bypass, • Malabsorption reduced absorption by

124 kcal/d• Restriction of food intake reduced energy

absorption by 2,062 kcal/d• Restriction 16 times more important than

Malabsorption

• The contribution of malabsorption to the reduction in net energy absorption after long-limb Roux-en-Y gastric bypass, Elizabeth A Odstrcil, et al. Am J Clin Nutr October 2010 vol. 92 no. 4 704-713


• 14 months after bypass, • Malabsorption reduced absorption of

combustible energy by 172 kcal/d• vs• Restriction of food intake reduced energy

absorption by 1,418 kcal/d

• (Why: Restriction Beginning to Fail)• The contribution of malabsorption to the reduction in net energy absorption after long-limb Roux-en-Y gastric bypass, Elizabeth A Odstrcil,

et al. Am J Clin Nutr October 2010 vol. 92 no. 4 704-713

Failure of RNYCaloric Effect


• Malabsorption ONLY 6%-11% reduction in calories

• RNY: Is Primarily a “Restrictive Procedure”

• Study Shows: Early signs of RNY caloric failure



• Dietary intake and net intestinal absorption of fat, protein, and carbohydrate were measured

• Calculated the total reduction in fat, protein, carbohydrate, and calories after RYGB

• Extent to which these reductions were due to restriction or malabsorption



• Fat absorption and malabsorption

• Average fat intake was

• 156 g/d before bypass,

• 50 g/d 5 mo after bypass, and

• 82 g/d 14 mo after bypass.


Correlation between the length of jejunum in the biliopancreatic (BP) limb and the reduction in fat absorption

Bile Acid Depletion:Fat Malabsorption &

Treatment of Diabetes

Most Bariatric surgeons DO NOT

Understand Bile/Bile Acids

Bile Acids: Not Just for Fat Absorption

• Bile Acids Needed for Fat absorption (Decreased Bile Acids => Decreased Fat Absorption)

• Studies show that bile acids also play a large role in glucose homeostasis

Bile Acids: Not Just DetergentsBile Acids as Hormones

• Bile acids as hormones act on several Critical receptors:

• Farnesoid X receptor (FXR) and • Pregnane X receptor (PXR), • Constitutive androstane receptor (CAR), • G-protein-coupled receptor TGR5. • Bile acids AS HORMONES regulate

Cholesterol, Glucose, and metabolism/energy homeostasis

What Most Bariatric Surgeons Do Not Understand

• Bile Acids Critical to Fat and Glucose Control in the Body

• Decreased Bile Acids =>Decreased Fat absorptionLowered Blood Glucose Levels

• MGB (Billroth II) => Decreased Bile Acids

• RNY does NOT Affect Bile Acid Pool

Study of long-limb Roux-en-Y gastric bypass

• Results: RNY does not cause bile acid malabsorption

• Fecal bile acid excretion average • Before: 0.8 g/d• Post Op 5 mo: 0.5 g/d • Post Op 14 mo: 0.7 g/d• Decreased Bile Acids Rx Diabetes• RNY Does Not Cause Loss of Bile

Bile Acid Sequestration Reduces Glucose Levels by Increasing Metabolic Clearance

• Bile acid sequestrants (BAS) reduce plasma glucose levels in type II diabetics

• BAS induced plasma glucose lowering by increasing metabolic clearance rate of glucose in peripheral tissues

• RNY Does Not Cause Loss of Bile• MGB Does Cause Bile Acid Losses

Bariatric Surgeons Forget History of GI Surgery

What have we learned from 100 years of GI Surgery?

Post Gastrectomy Steatorrhea

• For over 75 years authors have noted that • Fat Malabsorption/Steatorrhea common

post gastrectomy syndrome in some patients

• More common & Greater degree with • Billroth II >> Billroth I

• EVERSON TC. Experimental comparison of protein and fat assimilation after Billroth II, Billroth I, and segmental types of subtotal gastrectomy. Surgery. 1954 Sep;36(3):525-37

• MACLEAN LD, PERRY JF, KELLY WD, MOSSER DG, MANNICK A, WANGENSTEEN OH. Nutrition following subtotal gastrectomy of four types (Billroth I and II, segmental, and tubular resections). Surgery. 1954 May;35(5):705-18

• WOLLAEGER EE, WAUGH JM, POWER MH. Fat-assimilating capacity of the gastrointestinal tract after partial gastrectomy with gastroduodenostomy (Billroth I anastomosis). Gastroenterology. 1963 Jan;44:25-32

• …

100 Years of GI Surgery: Steatorrhea following Gastric Operations:

• What do we know:• Rare after gastro-jejunostomy or vagotomy

alone. • Rare after Billroth I• Especially Common after Polya gastrectomy

with BII. • (Butler, 1961)

Polya Type Gastro-Jejunostomy

NOTE:Large

Wide OpenGastro-

jejunostomy

Opinion Among BPD Surgeons

• Length of the Common Channel is the Critical Factor for Fat malabsorption & weight loss

• We review Animal studies and MGB results that suggest this is not the case

• Am J Surg. 2005 May;189(5):536-40, Common channel length predicts outcomes of biliopancreatic diversion alone and with the duodenal switch surgery, McConnell DB, O'rourke RW, Deveney CW

NUTRIENT ABSORPTION in the SMALL INTESTINE: Remember the Basics

• Duodenum and Upper Jejunum: most minerals

• Jejunum and Upper Ileum: carbohydrates, amino acids, water-soluble vitamins

• Jejunum: absorbs most of lipids and fat-soluble vitamins

• Terminal Ileum: Bile,Vit B12

Fat absorption and the Length of Billroth II Afferent Limb

• Experiment• Question: Increase length of

afferent limb associated with increased fat malabsorption

• Animals underwent a 50% distal gastrectomy with an antecolic

• Polya-type Billroth II anastomosis

Fat absorption and the Billroth II Afferent loop

• 50% distal gastrectomy with an antecolic

• Polya-type Billroth II anastomosis

• Afferent limb of

• 30cm, 60cm, 90cm

Fat absorption and the Billroth II Afferent Limb: RESULTS

• PreOp: Fecal excretion on a 127 Gm. diet 2.4% of the ingested fat.

• Similar results in dogs and in humans

• Animals with BII + 30cm afferent limbs

• Able to digest and absorb the dietary fat without any apparent difficulty


• Average fecal excretion diet was 2.4% of the ingested fat.

• Longer Loops steatorrhea increased• 30 cm. limb fecal fat 2.4% (No Change)• 60 cm. limb fecal fat excretion 10.2%• 90 cm. limb 28.2%

Fat MalabsorptionBillroth II (MGB) vs RNY

0

5

10

15

20

25

30

0 20 40 60 80 100

Bypass Limb Length

Fa

t L

os

t (%

)

MGBBillroth II

RNY


• Average fecal excretion Pre Op 2.4% of ingested fat

• Longer Limb increased steatorrhea• 30 cm. limb fecal fat 2.4% (No Change)• 60 cm. limb fecal fat excretion 10.2%• 90 cm. limb 28.2%

Fat MAL-absorption and the Billroth II Afferent LIMB

• Afferent limb most important factor post gastrectomy steatorrhea, “LENGTH”

• Animals with short afferent loops NO significant steatorrhea.

• As the length of the afferent limb increased, a concomitant and dramatic rise in fecal fat excretion was noted.

Fat MAL-absorption and the Billroth II Afferent loop

• Malabsorption is NOT due to bypass of the upper jejunum ALONE

• Kremen’s Study:• Over half the jejunum can be

bypassed without producing steatorrhea.

An Experimental Evaluation of the Nutritional Importance of Proximal and Distal Small

Intestine

• Arnold J. Kremen, et al.Ann Surg. 1954 September; 140(3): 439–447

Kremen, et al.

• “Experimental studies in dogs reveal that animals can bypass

• 50 to 70 per cent of their small intestine

• and maintain a near normal nutritional status”

Experimental Evaluation of the Nutritional Importance of Proximal and Distal Small Intestine

• Study showed that • Bypass of major lengths of the

proximal small intestine, • Weight is well maintained • No great interference with fat

absorption • NOTE:

Contradiction with Prior Study


• 50 - 70% of the small bowel bypassed

• Proximal and distal ends were exteriorized as a cutaneous stoma.

• Intestinal continuity was re-established by end-to-end anastomosis

50% of Jejunum Bypassed:No Weight Loss!

Massive bypass = No Effect

• The small intestine in adults is a long and narrow tube about 7 meters (23 feet) long

• 50% Bypass = 11.5 ft (3.5 meters)

• Minimal Weight Loss!

70% Bowel BypassedMinimal Weight Loss

Massive bypass = Little Effects!

• The small intestine in adults is a long and narrow tube about 7 meters (23 feet) long

• 70% Bypass = 16 ft (5 meters)

• 5% weight loss

70% Bypass = Little Effect

• Group IV animals, which were similar to Group I except that 70% instead of 50% of proximal small bowel removed from intestinal continuity,

• Lost about five per cent of their preoperative weight and then stabilized at this level.

Transit Time & Fat Absorption

• 50-70% Bypass

• Made Little Difference in

• Transit Time or

• Fat Absorption NOT affected


• CONCLUSIONS• The proximal 50 to 70 per cent of the small

intestine can be removed with no apparent ill effects.

• Weight is maintained, and protein and fat absorption are not significantly altered.

• Arnold J. Kremen, John H. Linner, and Charles H. Nelson

Bypass of Jejunum; Experimental Results:No Fat Malbsorption or Major Fat

Malabsorption

• 2 Studies; 2 Different Findings• Massive Small Bowel Bypass

=> Minimal Effects• Moderate Small Bowel Bypass

=>Major Effects• What is the Difference?

It’s the Billroth II

Billroth II + Moderate Bypass=

Fat Malabsorption and Good Weight Loss

RNY

• Primarily Restrictive

• Minor fat malabsorption

• No Malabsorption of Protein or Carbohydrate

• Restriction begins to fade early

Education

RNY = Minimal Fat Malabsorption vs MGB = Major Fat Malabsorption