Bariatric surgeries have become increasingly popular in New Zealand, with estimates of over 1000 patients having surgery in the public and private sector each year. These patients have increased nutrient needs and require vitamin and mineral supplements. In general, procedures that are more malabsorptive have a higher risk of nutritional deficiency, and require a higher degree of supplementation and more regular blood tests to ensure adequacy.
Surgeries include:
Gastric sleeve (GS) or sleeve gastrectomy
around 80% of the stomach is removed, with the patient losing weight due to reduced portion sizes.
Blood tests
LFTs
FBC
Iron studies
Folate
Vit B12
Calcium
PTH
HbA1c (if a prebariatric history of diabetes)
Roux-en-y gastric bypass (RYGB)
A small pouch is created from the stomach and connected directly to the small intestine. The remaining stomach and the first part of the small intestine are bypassed. Patients lose weight due to the reduced portion sizes and malabsorption.
One anastomosis gastric bypass (OAGB; also known as the “mini bypass”)
A variant of the RYGB. Uses only one anastomosis, and the limb length can differ (limb lengths >150cm are more malabsorptive).
Biliopancreatic diversion with duodenal switch (DS)
A gastric pouch similar to the gastric sleeve is formed, and a large portion of the small intestine is bypassed. Patients lose weight due to the reduced portion sizes and the larger amount of malabsorption. There is a higher risk of nutritional deficiencies.
LFTs
FBC
Iron studies
Folate
Calcium
PTH
Vit B12
Zinc
Copper
Vit D
HbA1c (if a prebariatric history of diabetes)
Check Vit ADEK if Steatorrhea
LFTs
FBC
Iron studies
Folate
Calcium
PTH
Vit B12
Zinc
Copper
Vit D
HbA1c (if a prebariatric history of diabetes)
Check Vit ADEK if Steatorrhea
LFTs
FBC
Iron studies
Folate
Calcium
PTH
Vit B12
Vit E + K (annually)
Single anastomosis duodeno-ileal bypass with sleeve gastrectomy (SADI-S) LFTs
A variant of the DS. Only uses one anastomosis, and is designed to be less malabsoptive than the DS.
FBC
Iron studies
Folate
Calcium
PTH
Vit B12
Vit E + K (annually)
Zinc
Copper
Vit D
Vit A
HbA1c (if a prebariatric history of diabetes)
Zinc
Copper
Vit D
Vit A
HbA1c (if a prebariatric history of diabetes)
Current situation
Bariatric multivitamins have been withdrawn from sale in New Zealand for having levels of certain vitamins and minerals above the allowable limit. This poses a significant risk to these patients, and they are likely to seek advice from their GPs on what alternatives they should take. Bariatric specific multivitamins were designed to meet these increased requirements.
Our Request
Please do not prescribe Mvite for this patient group – it is inadequate to meet their increased needs.
Encourage your patients to source their bariatric specific multivitamin online if at all possible. Companies are allowed to ship these products directly to patients from overseas, as long as they do not contain prescription levels of vitamins or minerals (ex: over 1000 IU vitamin D, over 24mg iron, or over 25mg zinc). Currently BN Healthy is shipping a range of their products to patients in New Zealand.
Complete more frequent blood test monitoring if patients are not taking their normal multivitamin to monitor for deficiency (every 6 months if not taking a bariatric multivitamin, every year otherwise).
If an over the counter option is required, we recommend Centrum Women’s twice daily as this is closest to meeting their nutrient needs. No over the counter supplement options will meet the needs for a DS or SADIS, please have them contact their original bariatric team.
Calcium and CVD risk
Following a gastric bypass, the main site of calcium absorption is bypassed. Experts agree that lifelong calcium supplementation is recommended. It is unknown in this population group whether calcium supplementation will adversely affect CVD risk, but if so, this risk is small and likely outweighed by the gastric bypass benefits. In line with expert opinion, we recommend supplementing with 500mg calcium per day, with 50,000IU units vitamin D once per month. Please note that for patients with a sleeve gastrectomy, additional calcium supplementation is not indicated.
International guidelines have been created to advise on what a patient will need based on which surgery they have had.
Full guidelines can be found here:
Clinical practice guidelines for the perioperative nutrition, metabolic,and nonsurgical support of patients undergoing bariatric procedures –ASMBS 2019
https://asmbs.org/app/uploads/2020/04/Mechanick-2020-AACE-TOS-ASMBS-Guidelines.pdf
British Obesity and Metabolic Surgery Society Guidelines on perioperative and postoperative biochemical monitoring and micronutrient replacement for patients undergoing bariatric surgery—2020 update
https://onlinelibrary.wiley.com/doi/full/10.1111/obr.13087
BOMSS GP Guidance
https://bomss.org/bomss-post-bariatric-surgery-nutritional-guidance-for-gps/