Prevalent low Mediterranean diet adherence and low folate status in a Spanish Km 0 Mediterranean coast population

Folate, vitamin B₁₂, riboflavin, and vitamin B₆, play interrelated roles in one-carbon metabolism, vital for several physiological processes.

To assess intake and status of these B-vitamins in an adult Mediterranean population unexposed to mandatory food fortification or B-vitamin supplementation, and to examine the associations with Mediterranean diet adherence (MDA).

A representative sample of adults aged 18-77 (n = 740) provided fasting blood samples and 3-day dietary records. MDA was assessed using the Trichopoulou score. Plasma folate, red blood cell folate (RBCF) and plasma vitamin B₁₂ were measured via microbiological assays. Riboflavin and vitamin B₆ status were determined by erythrocyte glutathionine reductase (EGRAC) and aspartate aminotransferase activation coefficients (EASTAC), respectively.

Intake below average requirement was observed in 39.5 % (for folate), 6.5 % (for vitamin B₁₂), 20.1 % (for riboflavin), and 19.6 % (for vitamin B₆) of the participants. Plasma folate <7 nmol/L, plasma B₁₂ < 148 pmol/L, RBCF <340 nmol/L, EGRAC ≥1.4, and EASTAC ≥1.6 occurred in 18.6 %, 1.6 %, 1.5 %, 35.9 %, and 56.0 % of participants, respectively. Overall, 82.64 % of participants had low MDA (score <6). Participants in the highest MDA quartile had higher folate intake (354.5 vs. 214.9 μg/day; P < 0.001), plasma folate (14.5 vs. 10.0 nmol/L; P < 0.001), and RBCF (895.7 vs. 692.8 nmol/L; P < 0.001) compared to those in the lowest quartile (score ≤2). Nevertheless, 15.5 % of high-MDA individuals did not meet the folate average requirements, and 8.5 % were folate deficient.

High vs low MDA was associated with better folate intake and status but this was not true for the other vitamins. Only 17.4 % of the population had high MDA and folate deficiency still occurred in this group. A fortification policy may be required, to prevent folate deficiency in the population.