Inappropriate serum levels of retinol, alpha-tocopherol, 25 hydroxyvitamin D3 and 24,25 dihydroxyvitamin D3 levels in healthy Spanish adults: simultaneous assessment by HPLC

Objective

Simultaneous assessment of the status of lipid-soluble vitamins; retinol, α-tocopherol, 25 hydroxyvitamin D₃ and 24,25 dihydroxyvitamin D₃ in serum of blood donors, paradigm of a healthy population.

Patients and methods

Serum samples were supplied by the Regional Blood Donors Center in Cordoba from 215 healthy Spanish individuals (166 males and 99 females). Target analytes were determined using liquid-liquid extraction and separation-detection by HPLC.

Results

The method was validated using standard reference material (SRM 968c, NIST). Standard errors were 1.4%, 2.1% and 1.8% for 25OHD₃, vitamin A and vitamin E, respectively.The ranges thus assessed were as follows: 17.1 ± 8.0 nmol/L, for 24,25(OH)₂D₃, 40.3 ± 34.6 nmol/L for 25OHD₃, 2.57 ± 0.7 μmol/L for retinol and 22.13 ± 8.30 μmol/L for α-tocopherol. Females showed lower serum levels of retinol (p < 0.01), α-tocopherol (p < 0.01) and 25OHD₃ (p = 0.028).A total of 10.4% subjects showed vitamin E deficiency, 85.4% had normal levels and 4.2% had high levels of vitamin E. 65.6% of the target subjects showed normal levels of retinol, and 1.6% had moderate or severe vitamin A deficiency. High levels of vitamin A were found in 32.8% of the subjects.Fourteen percent of the healthy subjects showed severe vitamin D deficiency (serum levels of 25OHD₃ < 25 nmol/L), 50.8% had vitamin D₃ insufficiency (25OHD₃ from 25 to 50 nmol/L), 17.6% of the subjects had suboptimal 25OHD₃ serum levels (25OHD₃ from 50 to 75 nmol/L), only 16.8% had an adequate status of 25OHD₃ and 0.8% had high levels of vitamin D (25OHD₃ > 200 nmol/L). Among subjects with vitamin D below 50 nmol/L, 49.38% had high levels of retinol (over 2.4 μmol/L). This association is considered a risk factor for osteoporosis and fracture.

Conclusions

The reported data of high prevalence of lipid-soluble vitamin values outside the physiological range have important repercussions on public health. These data also uphold the need for simultaneous measurement of fat-soluble vitamins as a valuable tool in clinical practice as well as in epidemiological studies for awareness and correction.