PUBLISHED ON: 13 September 2016

At Breast Cancer Care we’re often asked about the importance of getting enough vitamins following a diagnosis of breast cancer, and whether you might need to take a supplement. Here, one of our Helpline specialists looks at whether shorter days in autumn and winter might mean you should consider taking a vitamin D supplement. 

>> Read more about diet and breast cancer. 

Recently, there have been media reports about new Public Health England guidelines on vitamin D. This vitamin is an exception to the rule that most people will get enough of the vitamins they need through eating a varied diet. 

Sunshine icon

Vitamin D isn’t found very widely in the diet. Instead, it is mostly made in the skin through exposure to ultra-violet light. This is why it’s sometimes called the sunshine vitamin and why you get less vitamin D in the winter months in the UK.

Foods that contain vitamin D include oily fish, egg yolk, liver, red meat, butter and fortified fat spreads, and some fortified breakfast cereals.

Vitamin D is vital for good bone health because it allows you to absorb two essential minerals, calcium and phosphate. These two minerals help to build and repair bones and teeth.

It’s thought that around one in five adults in the UK may have low levels of vitamin D although a lack may not cause symptoms. It’s thought that symptoms such as aching muscles, joint pains, or tiredness and depression are sometimes caused by having too little vitamin D.

There are some risk factors and groups of people more likely to be deficient in vitamin D. These include:

  • having dark skin – people of Asian, African, Afro-Caribbean  and Middle Eastern descent are at higher risk
  • being over 65 – the skin of older people does not make vitamin D so efficiently
  • anyone who spends very little time outside in the summer – people who are housebound, shop or office workers, night-shift workers or people who cover their skin for cultural reasons.

In the UK, sunlight is only strong enough to make vitamin D on exposed skin in the middle of the day during April to September. Also, the further north you live, the less you are likely to be exposed to enough ultra-violet light in the summer. 

Previously, only children and adults over age 65 were recommended to take a daily vitamin D supplement. In July 2016, the Government’s Scientific Advisory Committee on Nutrition recommended that all adults should consider taking a daily supplement of 10 micrograms of vitamin D from October to March, as it may not be possible to absorb enough of the vitamin during the winter months.

Benefits and risks

It’s not advisable to take more than the recommended amount of vitamin D as an excess can lead to a build-up of calcium, causing serious ill-health.

Although the benefits of sunlight for vitamin D production are clear, it’s difficult to know exactly how much exposure you need. Also, excessive sun exposure increases the risk of skin cancer, so it’s important to enjoy the sunshine safely.

Dressed for sun care

If you’ve had axillary node surgery you should take particular care to avoid sunburn, as this could trigger lymphoedema (a swelling of the arm, hand or chest area).

Women whose cancers are sensitive to the female hormone oestrogen may be offered a hormone therapy called an aromatase inhibitor (AI). AIs reduce the amount of oestrogen in the body which, in time, may lead to a loss of bone density (osteoporosis). So it’s likely that your specialist will arrange a scan to check your bone density before starting an AI and at repeat intervals while you are taking it. Depending on the findings of scans you may be recommended to take a supplement of calcium and vitamin D to help protect your bones. In this case, you probably won't need to add an additional supplement but if you are unsure, talk to your specialist.

If you’re concerned about whether you’re getting enough vitamin D you can talk to your specialist team or your GP (local doctor) about whether to take a supplement. 

If you’re currently receiving treatment or taking a drug prescribed for another condition, it’s always best to check with your specialist or GP before taking any supplement, as some supplements may interact adversely with prescription medicines.

Here to help

If you have questions or concerns about this issue or any other breast-health related issue, you can call us free on 0808 800 6000.