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  • Joanna Injore

Do you need to take supplements after your cancer treatment?

Are you recovering from cancer treatment and now starting to focus on your diet? You might be still experiencing some treatment side effects like taste changes, low energy, lack of appetite so you know your diet isn't as good as it could be, so it seems natural to wonder if a vitamin supplement can help. As a cancer dietitian I will be sharing the info you need when it comes to vitamin supplements after cancer.

What are vitamins and minerals and why do I need them?

Your body needs vitamins and minerals for lots of different processes and most vitamins cannot be created (except vitamin D) so they must be supplied through your diet or supplements. 

Vitamins are classed as either ‘fat-soluble’ or ‘water-soluble’ (1 SOURCE):

Fat soluble vitamins are: Vitamin A, D, E and K

Water soluble are: The B vitamins (Thiamin, riboflavin, niacin, Vitamin B12, folate and vitamin C)

vitamins out a bottle cancer nutrition

How do I know if I need vitamin supplements?

You may be thinking I need to take vitamin and minerals supplements but how do you REALLY know if you need them? 

Well the best indication is from a blood test which shows a low level of that vitamin. Generally, blood tests do not routinely measure your vitamin and mineral levels so this is something you may need to specially request from your GP, hospital or privately. Blood tests can check your iron level (haemoglobin and ferritin level- your iron stores), calcium, vitamin B12, B6, vitamin D quite easily but you may need to make a special request other tests for zinc, magnesium and usually the doctor needs to have a good reason for checking these.

So if you don’t easily have access to a blood test what can you do? Well you guessed it you need to look into your diet. We mainly get our vitamins and minerals from the food that we eat, so checking your diet is providing enough of these is a good place to start.

One problem, after cancer treatment is may take a while to get back to your normal diet, especially if you have some side-effects from treatment like constipation, taste changes, or loss of appetite (see this blog for more about poor appetite), so you may be thinking is your diet providing the right mixture of foods?  

You also may be experiencing tiredness and fatigue after cancer so you may be wondering whether a vitamin or mineral supplement could help with that too.

Knowing what you are getting from your daily diet is key. In all my programmes (what it feels like to work with me) we start with a detailed analysis of what you are currently eating. A detailed report is produced for your first appointment showing what your current diet provides in terms of energy, protein, vitamins and minerals you can see an example report here then we start we create a personalised plan so you know exactly what you diet needs to include.

How much do i need?

So how much vitamins and minerals do you actually need? Your daily vitamin and mineral intake is based on your  age and gender, any medical conditions (and maybe ethnic group).

Did you know that vitamins and minerals are only actually needed very small amounts? We are talking about milligrams (mg) which is 1 thousand’s of a gram or micrograms (µg or Mcg) 1 millionth of a gram! 

supplement how much do you need image

So, you should be able to achieve this with following a varied balanced diet IF you are including all the food groups such as starchy carbohydrates (cereal, rice pasta, potatoes), dairy or dairy-free alternatives, protein foods (meat, fish, eggs, pulses or beans) and lots of fruit and vegetables. 

However, there are certain groups of people that require supplements as they are at a higher risk of deficiency (low levels).  Below are The Department of Health and Social care recommendation for particular at-risk groups:

Isn’t it better to have more vitamins?

Some vitamin and mineral supplements are available in high doses, but more does not mean better! 

We already know now that vitamins and minerals are only needed in small amounts so taking above these levels can actually be harmful as high doses can interfere with medications ( 1SOURE) eg Excess amounts off fat-soluble Vitamins like Vitamin A, D, E and K can build up in the body and could be harmful

There is another factor too, if you are taking high doses more than you body needs it is just wasteful! Water soluble Vitamins (Thiamin, riboflavin, niacin, Vitamin B12, folate and vitamin C) will not be absorbed in the body so will just end up in your wee! 

What about supplements for cancer?

Research into specific types of vitamins and minerals and cancer has shown that supplements have little effect on cancer risk. Selenium is a mineral supplement that has been investigated to see if it lowers your risk of cancer.  A very detailed scientific review by Cochrane (2) into selenium supplements found that when people who took these supplements it did not reduce their risk of cancer. Actually the data showed there was an association with selenium supplements and high-grade prostate cancer in people that took selenium supplements. 

The World Cancer Research Fund UK which is a respected charity that contininly keeps up to date with the science on nutrition, lifestyle and cancer, has reviewed lots of different studies on supplements. They suggests supplements are not needed to reduce your risk of cancer and recommends you avoid high dose supplements because they increase the risk of some cancers (3)

So how do I choose a vitamin supplement?

If you are still thinking about trying a vitamin supplement below are my top tips to consider:

Top tips when choosing a supplement  

  • Buy from a reputable company at your local chemist, supermarket or high street shop rather than an unknown company or online. This will ensure they meet the UK requirements for safety

  • Check the Vitamin supplements do not exceed the recommended daily amount known NRV’s (Nutrient Reference Values) i.e. should not exceed 100%

  • Avoid taking lots of different types of supplements as you may be doubling up on the same Vitamins unknowingly, for example Fish liver oil supplements often contain Vitamin A

  • Always read the label and check for the expiry dates

  • Only choose supplements for your age group (particularly for children) as the NRV will be vary depending on age

  • Always check the supplements you are taking with you doctor or pharmacist if you are taking other medication, in case of negative interactions

  • Don’t take vitamin/mineral supplements with caffeine containing drinks (tea/coffee) as this can reduce their absorption

  • Fizzy effervescent vitamin supplements contain 1g of salt per tablet! So not a good idea if you are trying to limit your salt intake!

  • And finally check with your dietitian to see if you actually need

If you are worried that your diet might not be providing the right vitamins and minerals or if you are taking lots of different supplements and you just need some help figuring out what you should be really taking, come join me for a free chat. Book it here


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