From the Guidelines
Vitamin B12 deficiency is the primary concern after bariatric surgery, as it can lead to irreversible neurological damage and megaloblastic anemia if left untreated. This is because bariatric procedures, such as Roux-en-Y gastric bypass and sleeve gastrectomy, reduce the production of intrinsic factor, which is essential for vitamin B12 absorption 1. The altered digestive anatomy also limits exposure of food to the stomach and proximal small intestine where B12 is normally absorbed. Symptoms of B12 deficiency include fatigue, weakness, neurological complications like paresthesias, and megaloblastic anemia.
Some key points to consider:
- Vitamin B12 deficiency may present several years after surgery due to the body's 2-year stores of the vitamin 1
- Vitamin B12 levels may not be a good predictor of deficiency, and methylmalonic acid (MMA) has been proposed as a better indicator, but this requires a sensitive plasma assay not routinely available in many areas 1
- Folic acid deficiency can also occur after bariatric surgery, but it is less common and less serious than vitamin B12 deficiency, and can even mask the symptoms of B12 deficiency 1
- Patients typically require lifelong B12 supplementation, usually in the form of intramuscular injections or high-dose oral supplements 1
It is essential to monitor vitamin B12 levels and consider supplementation to prevent deficiency, especially after procedures like RYGB and BPD surgery 1. Periodic blood tests should be carried out every 6 months to identify postoperative deficiencies, and additional testing may be necessary to confirm vitamin B12 status 1. In cases of doubt, it is better to treat vitamin B12 deficiency to prevent long-term complications 1.
From the FDA Drug Label
Doses of folic acid greater than 0. 1 mg per day may result in hematologic remission in patients with vitamin B12 deficiency. Neurologic manifestations will not be prevented with folic acid, and if not treated with vitamin B12, irreversible damage will result. A vegetarian diet which contains no animal products (including milk products or eggs) does not supply any vitamin B12. If folate levels are low, folic acid should also be administered The concerning thing to check after bariatric surgery, specifically regarding folate (Vitamin B9) or Vitamin B12 deficiency, is the potential for:
- Masking of a Vitamin B12 deficiency by folic acid, which can lead to irreversible neurologic damage.
- Malabsorption of Vitamin B12, particularly in patients with a history of vegetarian diet or those who have undergone bariatric surgery.
- Low folate levels, which should be addressed with folic acid administration. It is essential to monitor folate and Vitamin B12 levels closely after bariatric surgery to prevent long-term complications 2.
From the Research
Concerns After Bariatric Surgery
- The risk of nutritional deficiencies, including folate (Vitamin B9) and Vitamin B12 deficiency, is a significant concern after bariatric surgery 3, 4, 5, 6, 7
- Vitamin B12 deficiency is particularly frequent in patients who have undergone obesity surgery, especially those with malabsorptive procedures such as Roux-en-Y gastric bypass 4, 6
- Deficiencies in vitamin B12 and iron can lead to anemias, while deficiencies in vitamin D can result in hypocalcemia and bone demineralization 5
- Baseline micronutrient testing and postoperative screening are recommended to identify and treat nutritional deficiencies early 5, 7
- Supplements, including multivitamins, iron, vitamin D, folic acid, calcium citrate, and vitamin B12, are frequently recommended to prevent nutritional deficiencies 7
Monitoring and Prevention
- Regular, life-long follow-up of all patients who have undergone bariatric surgery is essential to monitor for nutritional deficiencies and other complications 3
- Routine nutritional screening and monitoring compliance with supplement regimens are crucial to prevent deficiencies 3, 5
- Blood work should be obtained every 6 months after surgery to identify and treat nutritional deficiencies early 7
- Evaluating levels of thiamine, copper, vitamin B12, methylmalonic acid, and homocystine is indicated in patients who develop neuropathies after bariatric surgery 7