Recent findings suggest a protective role for folates in the reduction
of
neural tube defects and possibly also coronary heart disease and cancer.
Consequently, an increase in the daily intake of folates is warranted,
which
emphasizes the need for quantitative as well as qualitative measurements
of dietary
folates. Milk plays an important part in the food chain in many Western
countries
today. Several studies suggest that folate-binding proteins might have
an impact on
folate absorption and therefore their concentrations are also important.
The mean
concentration of the predominant form of folate, 5-methyltetrahydrofolate
(5-CH3THF), was determined using HPLC in thirteen
selected dairy products; skim
milk powder, two pasteurized milks, UHT milk, two fermented milks, three
whey
products and four different cheeses. All results were corrected
for recovery by spiking
the samples with 5-CH3THF. Effects of storage of dairy
products on 5-CH3THF
concentrations were also investigated; generally small and
insignificant fluctuations
were found, except for hard cheese, in which 5-CH3THF
decreased significantly.
There was a significant seasonal variation in the folate concentration
of pasteurized
milk which peaked in the summer months. The concentrations of folate-binding
protein in skim milk powder and pasteurized milk analysed using an enzyme-linked
immunosorbent assay were similar. UHT milk and fermented milk, both of
which are
processed at temperatures >90°C, contained significantly lower concentrations
of
folate-binding protein.