Vitamin D: Could UV-mushrooms help fix the nation’s issue?

A government consultation on how to tackle the nation's vitamin D deficiency problem ends on Sunday.

One idea being floated is getting people to eat biofortified foods, such as mushrooms that have been exposed to UV light.

It is a process that makes the food extra-rich in the nutrient.

More than one in 10 adults in the UK is thought to be lacking in the sunshine vitamin, which is needed to keep muscles and bones healthy.

Too much vitamin D can be bad too though - a build-up of of it can cause too much calcium in the body.

That is why there is a debate about what is the best way to improve the nation's intake, since some people already get plenty.

The England-only consultation, led by the Office for Health Improvement and Disparities and the Department of Health and Social Care has asked for individuals or businesses to contribute with suggestions.

The next step will involve a national campaign to improve the vitamin status of the population.

There could also be legislation passed to allow food producers to put more vitamin D in foods that don't naturally contain it, in a process known as fortification, as well as growing produce and breeding meat to be more vitamin D-rich through biofortification.

Margarines used to have to be fortified by law, but the government dropped that requirement in 2013 to reduce the amount of regulations dairy farmers had to follow.

Some people are concerned that if many foods were fortified with various vitamins and nutrients, we might end up consuming too many. However, Dr Stacey Lockyer, from the British Nutrition Foundation, says this is unlikely.

"The safe upper limit for a nutrient, set by health authorities to help ensure that total intakes do not pose risks for public health, would always be carefully considered before the implementation of a food fortification policy," the nutrition scientist tells the BBC.

"Studies conducted across Europe - under the Odin Project - have looked at the inclusion of vitamin D-fortified foods, either singularly, but also in combination, and have concluded that diverse fortification strategies carry little risk of exceeding the safe upper limit for vitamin D and thus could safely increase population intakes."

People can get some vitamin D from their diet, but also make it in their skin when it is exposed to the sun.

There is no exact figure for how much time should be spent in the sun, but the charity Cancer Research says people should always be careful about skin cancer risk.

For a while now, the government has recommended everyone should consider taking daily vitamin D supplements during the autumn and winter to top up their levels.

Some people are more likely to be deficient - people who don't get outdoors much or who cover their skin, as well as people with naturally darker skin.

During the pandemic, more than 900,000 vitamin D supplements were given to people who were clinically extremely vulnerable and those in care homes to help avoid more deficiencies.

These free supplements were discontinued in February 2021, which clinicians from the Royal Osteoporosis Society (ROS) say is concerning, because it could lead to more people developing osteoporosis.

"Elderly people in particular face a perfect storm if vitamin D supplements are not made readily available, as do vulnerable individuals who cannot get out for UV exposure over a UK summer," they tell the BBC.

Now only eligible pregnant women, new mothers and children under four can get free supplements, which contain folic acid, vitamin C and D as part of the Healthy Start scheme.

"Targeting these groups is helpful but doesn't address the magnitude of the problem that exists from cradle to grave," they add.

Supplements can be purchased from most supermarkets and pharmacies, with a three-month supply costing under £3.

You should be able to get the right amount of vitamin D just by going out in the sun between March and September in the UK.

But during the winter months, the sun will not be enough.

Foods that naturally contain vitamin D include oily fish like salmon, sardines, herring and mackerel, red meat and egg yolks.

Some products, like breakfast cereals, are fortified with vitamin D, meaning it has been added to them. Researchers are also exploring biofortification - for example, rearing animals to produce vitamin-D rich beef, pork, chicken and eggs.

There are two important forms of vitamin D - D2 (ergocalciferol) and D3 (cholecalciferol). D2 generally comes from plants, such as mushrooms, while D3 comes from animal sources, such as eggs and fish, as well as our skin when it is exposed to the sun. Both D2 and D3 can be found in supplements.

Most Vitamin D supplements contain vitamin D3, which is typically produced from a wax called lanolin, extracted from sheep's wool, and so may not be suitable for vegans or those who do not consume dairy.

Dr Lockyer says you can still get the vitamins you need when you're vegan or vegetarian.

"Eggs are a useful source of vitamin D for vegetarians who eat them," she tells the BBC.

"Other food sources of vitamin D that are suitable for vegetarians and vegans are foods fortified with vitamin D such as some plant oil-based polyunsaturated fat spreads, some plant-based dairy alternatives - choose unsweetened versions - and some breakfast cereals - where fortified with a form of vitamin D suitable for vegans."

Dr Lockyer also says vitamin-D enriched mushrooms can be purchased instead of regular ones to help increase intake.

Research from March this year by YouGov found that nearly a third of adults (29%) in the UK can't identify a dietary source of vitamin D, while more than half of UK adults (54%) don't take any vitamin D supplements at all during the year.

The research, which was conducted on behalf of the ROS, also found that despite the pandemic providing more opportunity for many people to spend more time outdoors, adults were actually going outside less.

A total of 30% of UK adults said they were spending less than an hour outside on an average day, while 64% said they were spending two hours or less outside.

ROS chief executive Craig Jones says he is pleased the government is running the consultation, and wants free supplements to be top of the agenda.

"There are still people facing barriers to good bone health, and we're concerned that the rising cost of living might prevent even more people from following the advice to supplement," he says.

"Access to information and supplements should be available to everyone who needs it, and they shouldn't have to choose between their finances and their bone health."

Dr Lockyer has also expressed the British Nutrition Foundation's issues with vitamin D consumption in the UK, and says "multiple strategies" are needed to improve it throughout the population.

"Not getting enough vitamin D can lead to an increased risk of bone deformities such as rickets in children, and bone pain caused by a condition called osteomalacia in adults," she says.