Vitamin D important to protect against bowel diseases

Vitamin D important to protect against bowel diseases

Wider use of vitamin D fortified foods and dietary supplements to benefit bowel health, are suggested by new research from the University of Auckland.

In a study published in Molecular Nutrition and Food Research, lead author, Professor Lynn Ferguson from the University’s Auckland Cancer Society Research Centre, says that the optimal intake levels of vitamin D for an individual could be assessed using personalised genetic and genomic information.

“This would provide the very best disease prevention and remission,” she says. “Across a range of gastrointestinal disorders there is also increasing evidence that the symptoms and longer term consequences of several of these disorders could be benefited by either regular use of a vitamin D supplement, or consumption of 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 says. “At least in respect of gastrointestinal disorders, most of us would benefit from a substantially higher intake than we currently have."

“Public awareness of the risk of skin cancer from sunlight means that vitamin D from diet is more important than ever,” says Professor Ferguson. “Gastrointestinal diseases such as colorectal cancer and inflammatory bowel disease are becoming increasingly common worldwide, including among children and adolescents."

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

Professor Ferguson says genomic technologies have revealed several hundreds of genes associated with vitamin D actions.

“The nature of these genes emphasizes the potentially negative impact of changing vitamin D intakes without complementary human genetic and genomic data, including information on the gut microbiome,” she says.

The report notes that although 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.

Vitamin D in foods is fat soluble and needs further conversions to become active, says Professor Ferguson.

“It has been claimed that it is almost impossible to obtain sufficient vitamin D from the diet alone, without supplementation,” she says. “In Australasia for example, fortified margarine appears as a major dietary source of vitamin D, while fortified milk has become an important source of this nutrient, especially for young children.

“Perhaps more importantly, more research is needed to confirm the potential efficacy of these and other dietary sources in meeting vitamin D requirements,” says Professor Ferguson. “The importance of vitamin D is not coming across to all population sectors at present, so vitamin D-enhanced foods might need to become better advertised and advocated by consumer groups.”

She says vitamin D intake could be tailored according to human genotype and understanding of the gut microbiome, rather than directed in response to symptoms as at present.

“Optimal use of such technology would occur alongside more traditional pharmaceutical approaches,” says Professor Ferguson. “In the future, we could see the potential of expanding this approach to a form of routine genetic screening at birth, coupled with pre-emptive nutrition in individuals discovered to be at high risk of gastrointestinal disorders.”

ENDS

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