Additional mineral in milk can help prevent cancer
Consumer diets are lacking in selenium and improving
the content in milk could offer a valuable alternative to
other diet supplements. Richard Allison reports
SELENIUM enriched milk could have an important role in reversing the decline in selenium intakes in the UK, reducing the number of deaths from strokes and prostate cancer, according to researchers.
Human intakes of selenium in the UK have fallen to roughly half of the recommended daily allowance, says Ian Givens, manager of the ADAS Nutritional Sciences Research Unit, Stratford-upon-Avon, Warks.
"This decrease is the result of the shift from using Canadian wheat to home-grown wheat for bread making. Canadian wheat naturally contains more selenium."
Declining selenium intakes is a concern. Clinical studies prove low blood levels can lead to a four-fold increase in deaths from strokes, says Prof Givens. Selenium supplements have also been shown to halve the number of deaths from prostate cancer.
Prof Givens believes that increasing selenium intakes in the UK can be achieved by encouraging people to take selenium pills, increasing selenium in UK-grown wheat by applying selenium fertilisers or by enhancing selenium levels in milk."
Only a minority of people generally take dietary supplements and there are environmental concerns with applying selenium to soil because it can be toxic at high levels. This leaves selenium-enhanced milk, which can be produced by changing rations fed to cows.
As part of a four-year DEFRA-funded study at ADAS, strategies for increasing selenium in milk were investigated.
But this has to be achieved while keeping dietary levels within the EU legal maximum of 0.5mg/kg of feed, he explains.
"Milk selenium concentration was increased to 28mg/kg, more than 2.5 times above normal milk, when an organic form of selenium was fed to cows at 0.4mg/kg feed." This milk concentration is also higher than the optimum level of 20mg/kg adopted in Finland, he adds.
Increasing milk selenium levels in standard UK milk to 28mg/kg equates to an additional 11% and 14% of the total recommended daily allowance for men and women respectively, says ADAS researcher Angela Moss.
However, the organic form of selenium fed in the trial is not yet legally approved for use in livestock rations in the EU, says Prof Givens. "Only authorised selenium additives can be used in feeds."
The standard approved form of selenium tested in the trial, sodium selenite, did not substantially increase milk selenium levels when fed within current legal limits.
This is due to the greater availability of selenium to cows in the organic form, compared with the standard inorganic form. Adopting the organic form may also have environmental benefits by reducing selenium losses in dung, as more is going into milk.
The study shows it is possible to produce selenium rich milk, but feed legislation and the lack of financial incentives will continue to prevent producer uptake, he says.
Prof Givens also highlights that health claims cannot be used to market food products. "Selenium rich milk cannot be sold on the basis of the health benefits of consuming extra selenium."
To address declining selenium intakes in the UK, there needs to be a national strategy with premiums paid to producers, says Dr Moss. "Until then, selenium rich milk will not have a role in improving selenium intakes."
Human intakes of selenium in the UK are roughly half of the recommended daily allowance, says Ian Givens.
SELENIUM RICH MILK
• Easily achieved, but still illegal.
• Health benefits.
• UK strategy needed.