Vitamin D sparks a movement in bowel health

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Vitamin D could play an important role in bowel problems, new research from the University of Auckland suggests.

The number of gastrointestinal disorders is rising, according to Professor Lynnette Ferguson, and there's a strong link to vitamin D deficiency.

While it's good New Zealanders are being cautious about overexposure to the sun, she said, our vitamin D levels are falling and a lot of people aren't compensating for that.

"A lot of us are just not getting as much vitamin D as we ought to be, we're being much more conscious - as we ought to be about sunlight exposure, but that's our main source of vitamin D," Professor Ferguson, of the University's Auckland Cancer Society Research Centre, said.

The country needs to be more proactive, both with vitamin D supplemented foods, and with monitoring people's vitamin D levels, she said.

In a study published in Molecular Nutrition and Food Research, Professor Ferguson said there was increasing evidence that people who suffer symptoms and long term consequences of several bowel disorders could benefit from either regular use of a vitamin D supplement, or eating vitamin D-enhanced foods.

"Too much vitamin D can possibly also have adverse effects, so defining an optimal level of vitamin D for an individual is important," she said. "At least in respect of gastrointestinal disorders, most of us would benefit from a substantially higher intake than we currently have."

Gastrointestinal diseases, such as colorectal cancer and inflammatory bowel disease, were becoming increasingly common worldwide, including among children and adolescents, she said.

"This is a substantial burden on healthcare and a changing vitamin D intake through reduced exposure to sunlight not compensated through diet, may play a key role in susceptibility to such disorders.

"Although there is justification for increasing vitamin D intake overall for such diseases, optimal intakes will vary among individuals."

Vitamin D intake could be tailored according to human genotype and understanding of the gut microbiome, rather than directed in response to symptoms, as is the current method, she said.

"In the future, we could see the potential of expanding this approach to a form of routine genetic screening at birth, coupled with preemptive nutrition in individuals discovered to be at high risk of gastrointestinal disorders."

Vitamin D Factbox

Few foods contain significant amounts of vitamin D.

Important sources in the diet can include fatty fish, such as salmon or tuna, fish liver oils and eggs (especially egg yolks).

Small amounts of vitamin D are also found in beef liver, cheese and other dairy products.

- NewstalkZB, NZME.