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Vitamins and minerals are important nutrients your body needs to work properly and stay healthy.

After weight loss surgery it is important to carefully follow dietary advice and to keep an eye on your vitamin levels. This is partly because of a change in diet but also in a gastric bypass and sleeve, the body is less able to absorb vitamins and minerals. This is because of the changes to the structure of the digestive system, bypassing the small intestine or the removal of part of the stomach. Key ones to note, amongst others are vitamin D, Iron, vitamin B12 and calcium.

Deficiency in these important vitamins and minerals can cause serious health repercussions, such as; anaemia, nerve damage and brittle bones. It is important you have a full bariatric nutritional list of bloods taken at 6 and 12 months post surgery to find out your vitamin and mineral levels. After that you should have these taken annually.

So, we know that these vitamins and minerals are important but function to they play in your body?


Vitamin D

Vitamin D (calciferol) is a fat-soluble vitamin, which is vital to aid the absorption of calcium from our gut, and so has an important role in maintaining bone strength and density. It has many roles in the body including the regulation of the amount of phosphate in our body, our immune system and reduction of inflammation. 90% of our daily vitamin requirement is obtained by the action of UVB sunlight on the skin (only during April – September in the UK) 10% is obtained through our diet with foods such as oily fish (sardines/salmon), liver, egg yolks, fortified margarine and fortified breakfast cereals.


Vitamin B12

Vitamin B12, also known as cobalamin, is necessary for normal functioning of the nervous system and for forming red blood cells. A protein, called intrinsic factor produced by the parietal cells of the stomach linning, is needed to absorb B12. After weight loss surgery smaller amounts of this protein are formed, which means the body finds it very difficult to absorb the vitamin in the last part of the small intestine.



Calcium is needed for the development and growth of teeth and bone tissue. It is also required for the normal functioning of muscles and nerves. Calcium is found mainly in dairy products but also in green vegetables and sardines.



Iron is needed to make healthy red blood cells as well as being a key part of the immune system to fight infection as well as building good hair and nails. Good sources of iron include liver, meat, poultry, fish, green vegetables, lentils, egg yolks and wholegrain products.

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