Bariatric Surgery and Vitamin B12, what do I need to know?


Vitamin B12 deficiency can be a complication after bariatric surgery.

Malabsorptive surgeries such as the gastric bypass and the duodenal switch (rarely performed in the UK) are at higher risk of deficiency.

Vitamin B12 is often prescribed after bariatric surgery to prevent deficiency.

Vitamin B12 is absorbed in the small intestine. The lining of the mouth is also capable of absorbing vitamin B12 from food, but it is a small insignificant amount.

The stomach produces a glycoprotein called intrinsic factor which is essential for the absorption of vitamin B12 in the small intestine.

Why is vitamin B12 needed?

Vitamin B12 helps keep the body’s nervous system and blood cells healthy. Vitamin B12 also helps prevent megaloblastic anaemia.

Deficiency of vitamin B12 occur after bariatric surgery

Bariatric surgeries either reduce the size of the stomach or lessen the absorption of nutrients or both.

In Gastric Sleeve surgery the reduced size of the stomach results in a decrease in ghrelin (the hunger hormone) and reduced food intake.

There is also reduced production of an intrinsic factor which is needed for vitamin B12 absorption.

In Gastric Bypass surgery, the part of the stomach where the intrinsic factor is produced is avoided and never exposed to food.

When does deficiency of vitamin B12 occur?

The liver can store up to 3 years requirement of vitamin B12, so deficiency does not usually happen early after bariatric surgery.

Studies show that a significant number of patients become symptomatic within 1-2 years of gastric bypass surgery if not supplemented with Vitamin B12. Vitamin B12 injections are usually prescribed every 3 months for life following Bariatric Surgery. There are other forms of vitamin B12 available (sub lingual and nasal spray.) You should discuss this with your bariatric surgeon or bariatric dietitian.


Signs and Symptoms of vitamin B12 deficiency:


  • Feeling Weak
  • Fatigue
  • Dizziness
  • Loss of appetite
  • Diarrhoea
  • Painful swollen tongue
  • Pins and Needle sensations in the hands and feet
  • Nerve damage
  • Abnormal heart function
  • Poor Memory


Vitamin B12 supplementation is important after bariatric surgery, especially those patients who have had Gastric bypass surgery.

The truth about portion sizes following bariatric surgery.


Bariatric surgery creates a portion control system. There are slight variances with the different surgery options, but generally:

  1. In the early days following weight loss surgery you will only be eating a few spoonfuls of pureed food several times a day.
  2. After 3-4 weeks you will progress onto small portions of soft, mushy foods
  3. After 3-6 months you will have typically progressed onto a normal texture diet, your portion size is typically a side plate portion of food.

There is no reason why you cannot follow a normal healthy eating pattern, eat out with friends and have a normal healthy social life.

The Gateway Health team prepare you fully before surgery so that you are organised and have appropriate foods ready at home for after your discharge from hospital.

We give you step by step written advice also and follow up daily after your discharge from hospital, to reassure and guide you through the dietary stages and to be on hand for any questions or advice you may need.

Our aftercare also includes behavioural and emotional change support.

Everybody is motivated to lose weight for different reasons, what’s yours?

We all know that losing weight decreases your risks of dying early from weight related illnesses such as type 2 diabetes, heart disease, stroke, some cancers, high blood pressure, high cholesterol etc.

But there are many other benefits to losing weight …….

Improved sleep

Less joint pain

Increased energy

Increased confidence

Improved mood

Better complexion

People usually treat you better

Your children will eat better

You often are more open to trying new experiences and activities

Breathe easier

Clothes look and fit better

Sex drive improves

Your memory may improve

Food tastes better

You save money as not spending as much on food


Whatever your reason to lose weight, whether it is to improve health, confidence, mood, energy levels or to live longer…….. you get all the benefits if you make a success of it.

Help my relationship is changing!


After weight loss surgery your lifestyle changes, your habits change, your body shape is decreasing, your energy is increasing, and your health is often improving.

These things can often have a positive effect on your personal relationships, especially when your partner or significant others are understanding and supportive of the changes. Often their quality of life can improve too!

These changes can be very positive although at times relationship difficulties can arise.

The people in your life can react differently towards you, such as trying to consciously (or unconsciously/not realise they are doing it) sabotage your efforts,

They might not have faith in the fact that you can stick to your new lifestyle.

There could be jealousy, jealous of your successful weight loss and your courage at having done something positive to improve the quality of your life and your health.

Sometimes there is insecurity, they may worry that now you may want to find a different partner, friends might find the new you ‘boring’

Try to speak to your partner/the important people in your life as to how they can support you, explain what you have had done and the changes this will mean to your life long term, placing emphasis on all the positive gains… better health, improved energy, encourage them to voice their fears and openly discuss the changes.

For long term success following bariatric surgery and to avoid the real risk of future weight gain, it is essential that permanent behaviour changes are made, and emotional needs are understood and met in a healthier way.

Are you prepared to make the long-term changes to achieve a long-term good result?


Don’t kid yourself, Bariatric Surgery is not a quick fix. Yes, you are more than likely to lose weight in the early weeks and maybe months after surgery, but that weight can and often is regained.

For long term success you certainly must change your dietary and lifestyle habits and become more physically active, but have you considered that bariatric surgery can only help with your physical hunger but not your emotional hunger?

Have you used food as a means of coping with your emotions in the past? For example, eating when you feel low in mood, anxious or stressed?

You are going to need to learn different healthier means of dealing with your emotions. Who is going to guide and support you? If you can no longer self soothe or calm yourself with food, how will you manage with these emotions?

Choose a Bariatric provider who offers an after-care package that will fulfil your potential needs. Check out the experience and specialty of each member of the team, not just the Surgeon! Of course, when you are looking for a provider, check out the experience and safety record of your bariatric surgeon. The National Bariatric Surgical Register (NBSR) gives information on every bariatric surgeons’ statistics.

Your Aftercare programme, does it cover dietary, lifestyle and psychological support? Are the team Weight loss surgery specialists? Not simply an aesthetic clinic adding on weight loss surgery procedures. Bariatric Surgery is a real specialty which should be managed by experts in the field.


Surgery Overview.

Your bariatric team should discuss the differences between the different procedures, the pros and cons of each procedure before you decide.

It is vital to understand that bariatric surgery is only a tool to help you lose weight. You will have to make life long changes: dietary changes, lifestyle, activity and mindset changes. Otherwise you most likely will get poor results and/or regain weight.

I will explain how the different weight loss operations work and what lifestyle changes needed to achieve and maintain a good weight loss result.


The gastric band works by restricting the amount of food eaten and reduces your portion sizes, but only when used correctly. It is quite easy to cheat the gastric band by eating the wrong texture of food.

An adjustable Silicone band is placed around the top of the stomach which creates a small stomach pouch. The band has tubing attached which leads to a port, which is placed underneath the skin. The band is adjusted by a needle entering the port, injecting fluid in or out to the port to increase or decrease the level of restriction felt. Only health professionals trained in this procedure can do band adjustments.

On average patients lose approximately 40-50% of their excess weight loss in the first two years after surgery, when they work with the band correctly.

The gastric band is reversible, it can be removed if problems happen. Long term risks are things such as: Band slippage, erosion, problems with the port or tubing, band infection and esophageal dilation.


Gastric Band rules to live by..

Once you have moved through the post-operative dietary stages:

  1. Eat dry Textured food (except for the early weeks following surgery and following gastric band adjustments) Wet mushy foods will slide through the band and you will feel very little restriction.
  2. Do not eat and drink together
  3. Keep calories in drinks low
  4. Take only small bites of morsels of food
  5. Chew thoroughly, approximately 20 times for each morsel of food
  6. Wait a minute after you have swallowed your food before putting more food into the mouth.
  7. No snacking between meals.
  8. Mindful eating to a avoid vomiting and stretching the stomach pouch above the band
  9. Multi vitamin and mineral supplement for life.

Generally, patients who tend to eat large savoury meals and do not have a particularly sweet tooth can be suitable for a gastric band.

Sometimes a patient may choose a gastric band as they feel the other surgical options are too drastic.

The gastric band requires a strong commitment to attending clinical follow up for gastric band adjustments appointments and to a strong commitment to following the rules of how to work with the band.



Approximately 75% of the stomach is removed. This reduces the amount of food that you can eat. Ghrelin (The hunger hormone) is reduced which reduces your appetite. On average patients lose approximately 70% of their excess weight lost in first two years following surgery. Generally, there are less long-term problems in comparison to the gastric band. However acid reflux can occur and if you over eat, over time the new stomach can stretch

Gastric Sleeve rules to live by..

Once you have moved through the post-operative dietary stages:

  1. Normal balanced healthy diet
  2. Separate eating and drinking (Do not drink and eat food together, wait 30 mins after finishing food, before having a drink)
  3. Keep calories in drinks low
  4. Mindful eating to avoid stretching the pouch long term
  5. No snacking between meals
  6. Multi vitamin and mineral supplement daily for life
  7. Vitamin B12 injection every three months for life



The gastric bypass restricts your portion size and not all the calories you eat are absorbed. Your appetite is reduced. A small stomach pouch is made (approx. size of a golf ball) which is connected to a loop of the small bowel (The duodenum is bypassed). The remaining stomach and small bowel are reconnected further downstream where all the digestive juices from the stomach, liver and pancreas mix with food and allow some of it to be absorbed.

On average patients lose approximately 80% of their excess weight in the first two years after surgery. The gastric bypass can put type two diabetes into remission. Many patients tell us that their likes and dislikes of food have changed for the better. Dumping Syndrome is common, especially during the first year after a bypass. Nutritional deficiencies can occur as not all nutrients are absorbed. You can stretch the pouch by repeatedly over eating.


Gastric Bypass rules to live by..

Once you have moved through the post-operative dietary stages:

  1. Separate eating and drinking (Do not drink and eat food together, wait 30 mins after finishing food, before having a drink.)
  2. Keep calories in drinks low.
  3. Mindful eating to avoid stretching the pouch long term.
  4. Avoid snacking between meals.
  5. Multi vitamin and mineral supplement daily for life.
  6. Vitamin B12 injection every three months for life.