Levels of the vitamin in cheese were not affected by processing, storage for a year, or thermal treatments, with 91 per cent of the vitamin D3 added to the milk being measured in the final cheese, researchers report in the Journal of Agricultural and Food Chemistry.
“Our findings clearly demonstrate that Cheddar and low-fat cheeses are suitable foods for vitamin D3 fortification,” wrote lead author Dennis Wagner from the University of Toronto.
“These findings will help to validate this approach for expanding the dietary sources of this essential nutrient for consumers. This will ultimately increase vitamin D intakes in the population, which are currently too low, and could help bring about the public health benefits that result from a greater consumption of vitamin D.”
The vitamin is produced in the body on exposure to sunlight, but increasing vitamin D levels via sunlight or supplements has been a source of ongoing debate.
In the US, where over 1.5 million people are diagnosed with skin cancer every year, experts are pushing supplements, claiming recommendations for sun exposure are "highly irresponsible".
Another push for supplements comes from the fact that intakes are low from dietary sources coupled with a lack of sunshine in northern climates, has led to estimates that as much as 60 per cent of northern populations may be vitamin D deficient.
In adults, vitamin D deficiency may precipitate or exacerbate osteopenia, osteoporosis, muscle weakness, fractures, common cancers, autoimmune diseases, infectious diseases and cardiovascular diseases.
Another avenue that has been explored is the fortification of certain foods, predominantly dairy. Fortification of fluid milks and margarine products was made mandatory in Finland in 2003-2004, while other European countries do not allow for any fortification.
“To our knowledge, the fortification of reduced-fat cheese with vitamin D3 has never been reported,” wrote Wagner.
Vitamin D refers to two biologically inactive precursors - D3, also known as cholecalciferol, and D2, also known as ergocalciferol. Both D3 and D2 precursors are hydroxylated in the liver and kidneys to form 25- hydroxyvitamin D (25(OH)D), the non-active 'storage' form, and 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active form that is tightly controlled by the body.
Cheese filled with sunshine
Wagner and co-workers, fortified milk to produce an expected final vitamin D3 concentration of about 100 International Units per gram, and then made Cheddar and low-fat cheese from this.
The vitamin was not degraded during processing, said the researchers, nor did the ripening process of one year at between three and eight degrees Celsius. Thermal treatments at 232 degrees Celsius also did not affect vitamin D3 levels.
Recovery of vitamin D3 from the fortified Cheddar and low-fat cheeses were 91 and 55 per cent, respectively.
Moreover, the vitamin D3 was found to be distributed uniformly throughout the cheese, said the researchers.
“We conclude that industrially manufactured Cheddar and low-fat cheeses are suitable for vitamin D3 fortification,” wrote Wagner and co-workers.
The researchers were affiliated with the University of Toronto, Mount Sinai Hospital, the Egyptian National Research Centre, the University of Saskatchewan, and Ryerson University.
Bioavailability study
Recently the same researchers reported in the Journal of Nutrition that eating the vitamin D-fortified cheese resulted in the same blood rises in the vitamin as from supplements.
To read NutraIngredients.com’s report of this study, click here.
Source: Journal of Agricultural and Food ChemistryPublished online ahead of print, ASAP Article, doi: 10.1021/jf801316q“Vitamin D3 Fortification, Quantification, and Long-Term Stability in Cheddar and Low-Fat Cheeses”Authors: D. Wagner, D. Rousseau, G. Sidhom, M. Pouliot, P. Audet, R. Vieth