Bone health and bariatric surgery: vitamin D and calcium 

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What is this information about?

This information is about how you can keep your bones healthy after you have had bariatric surgery. It explains:

• why bone health is important 
• how bariatric surgery may affect your bone health 
• why vitamin D and calcium are so important for your bone health 
• how you can safely make sure that you have enough vitamin D and calcium in your diet 
• other ways to improve your bone health

Why have I been given this information?

You have been given this information because you are due to have, or have had, bariatric surgery. 

Following the advice in this information can help you to, for example: 

• have healthy bones and avoid getting conditions such as brittle bones (osteoporosis) or soft bones (osteomalacia) 
• protect your immune system so it works well to fight off infections  
• avoid symptoms such as tiredness.

Why is bone health important?

Having bariatric surgery can make it more likely that you will get bone conditions which harm your bones.  

This is because after bariatric surgery you may:

• not be eating enough of foods with the vitamins and minerals that you need to keep your bones healthy 
• not take vitamins and minerals into your body and bloodstream (absorb them) as well as you did before you had bariatric surgery 
• lose muscle that supports your bones and helps them to move 
• have changes to your hormones which can weaken your bones.

What must I do to protect my bone health after I have had bariatric surgery?

It is important that you:

• have a diet (what you eat and drink) that is good for your bone health 
• take supplements of the vitamins and minerals that you need more of, for life. 
• do exercise that will strengthen your muscles and bones (weight bearing exercise).

Vitamin D 

Why is it important for me to have enough vitamin D after I have had bariatric surgery?  

Vitamin D is important for: 

• helping your body to take calcium into your bones to keep them healthy 
• reducing inflammation (swelling, redness, pain and heat in your body). Too much inflammation over a long period can damage your body. 
• helping your immune system to work well 
• making you feel less tired 
• controlling phosphate levels so that they are balanced and help maintain the material that bone is made up of (the bone matrix). 

How do people usually get the vitamin D that their bodies need?  

Vitamin D is often called the sunshine vitamin.  Our bodies can make 90% of the vitamin D that we need through a chemical reaction that happens when we get UVB sunlight on our skin.  

This does not happen all year round. In the UK our sunshine is only strong enough to make vitamin D from April to September, and ideally between 11am and 3pm during these months. 

For most people the other 10% of vitamin D that they need comes from foods. Foods high in vitamin D include: 

• oily fish such as salmon, sardines, herring, and mackerel 
• red meat such as beef, lamb or pork 
• liver 
• egg yolks 
• foods with soya in them 
• foods such as yoghurts or spreads (margarines) which have had vitamin D added to them (foods fortified with vitamin D). 

What happens if I do not get enough vitamin D? 

Your bones can become soft (you get osteomalacia). This can lead to bone problems, pain and muscle weakness. 

Who may not get enough vitamin D? 

Low vitamin D is more usual if you: 

• are overweight 
• are unable to leave your house (are housebound) or are indoors for long periods 
• cover much of your skin with clothing for cultural reasons 
• are aged over 65 years 
• have black or brown skin (for example if you are of African, African-Caribbean or South Asian origin).  This is because your body can not make enough vitamin D in areas of the world or times of the year with low levels of sunlight. 
• your body does not take in (absorb) the nutrients in your food (including vitamin D) as well because you have had bariatric surgery 

Do I need to take a vitamin D supplement? 

After bariatric surgery, you will need to take 50 to 100 micrograms (2000 to 4000 IU) of vitamin D daily. You will need to take a higher dose if blood test results show that your vitamin D level is low.  

How do I know if my vitamin D level is okay? 

Vitamin D levels can be checked with a simple blood test. It should be checked before your operation and at least once a year thereafter. We will talk with you about your vitamin D levels in your bariatric appointments.  

Is there a chance that I may take too much vitamin D?  

Taking too much vitamin D is rare. Doses below 10,000IU a day are not likely to be harm your health.  

Calcium 

Why is it important for me to have enough calcium after I have had bariatric surgery? 

Calcium is important for: 

• making sure that your bones and teeth are strong 
• helping your blood to clot. This helps you to avoid bleeding too much and to heal wounds.  
• making sure that ‘signals’ can move along your nerves. If you do not have enough calcium it can lead to nerve and muscle conditions such as cramp, weakness or fits (seizures). 

After bariatric surgery you are more likely to have low levels of calcium. This is because: 

• your body may not take in (absorb) food and the nutrients it has in it as well  
• you are eating smaller portions of food. 

Is there a higher chance that I may get osteoporosis (brittle bones) after my bariatric surgery?

Osteoporosis is a condition where your bones become weak and there is a higher chance that they may break (fracture). You do not usually notice any symptoms if you have osteoporosis. The first sign that you have it is often that you have a broken or fractured bone. 

If you have had bariatric surgery and have low levels of calcium, there is a greater chance that you may get osteoporosis. 

There is a higher chance that you may get osteoporosis if you:

• have family members who have had osteoporosis 
• do not eat many calcium rich foods such as milk, cheese, yoghurt, tofu or canned fish 
• do not take your vitamin and mineral tablets as often as you should 
• have already had a broken or fractured bone 
• are aged 50 or over 
• are female and after your menopause 
• drink or smoke heavily 
• drink too much caffeine. Aim to have no more than four cups of coffee a day.  
• have a condition, or have had a medical procedure, which means that your body does not absorb food or nutrients as well. For example, you have coeliac disease or have had bariatric surgery. 
• have a hormone-related condition such as an over-active thyroid or reduced amounts of sex hormones.

What can I do myself to help build healthy bones?

To help build healthy bones do:  

• eat plenty of different types of food (have a varied diet) 
• have at least three portions of food from the dairy food group. For example, milk, cheese and yoghurt. 
• take your vitamin and mineral supplements every day. Be aware, you should do this for life. 
• exercise often.

What exercise should I do to make my bones strong and healthy?

To get your bones strong and healthy and keep them that way do: 

• activities where your feet and legs support your weight (weight-bearing exercises). These include things such as walking, climbing stairs, running, or sports such as badminton or basketball. 
• exercises which use your muscle strength (resistance exercises). You can do these using things such as: 
  • your own body weight (for example sit-ups or step-ups) 
  •  weights. This could be things such as dumbbells or kettlebells or even household items such as cartons of milk or bags of rice. 
  • resistance bands.

How much calcium do I need each day?

You need 1200-1500mg of calcium each day from food and supplements.

• Supplements should be labelled to say how much calcium they contain.  

• Look at the nutritional information on the pack to find out how much calcium packaged food contains. 

How much calcium do I need from food?

Do make sure you get at least 700mg of calcium every day from the food and drinks that you have (your diet). 

This is important as your body can use the calcium in food to make your bones stronger more easily than the calcium in supplements. 

The table below show how much calcium there is in portions of food which are good sources of calcium. 

You can use it to give you ideas for how you could get at least 700mg a day of calcium for your food. 

For example: 

1 glass of plant- based milk (300mg of calcium) 

plus 

half a tin of sardines (300mg of calcium) 

plus 

100g of boiled kale               (150mg of calcium) 

adds up to 750 mg of calcium. This means you have had just over the minimum of 700mg that you must have.  

Do I have to take a calcium supplement after my bariatric operation? 

Yes. After your bariatric operation, do take a supplement containing at least 500mg calcium every day.

• Take your supplement with food 
• Avoid having tea, coffee or iron supplements within two hours of taking your calcium supplement 
• Take a vitamin D supplement. This will help your body to absorb the calcium in your calcium supplement.

• You can reduce the chance that you may get kidney stones by drinking plenty (staying hydrated). 
• If you are unsure about whether you may have a higher chance of getting kidney stones you can talk with us about this at your bariatric appointment.

How do I know my calcium level is ok?

The calcium level in your bones cannot be tested with a blood test. We refer some people for a bone scan to find out how much calcium they have in their bones, but most people do not need this.  

Please talk with your doctor or dietitian if you: 

• are pregnant or planning to become pregnant 
• have, or think you may have, any of these conditions: 
  • a kidney condition 
  • a condition which affects your parathyroid hormone levels 
  • high calcium in your blood or pee (urine) 
  • cancer that affects your bones.

Who can I contact if I need further information or support after I have read this information?

Please contact the Bariatric Surgery Dietitians. 

Phone: 01243 831655 

We aim to respond to your query within three working days.