On 20th March 2015 Public Health England published the National Diet and Nutrition Survey Rolling Programme (NDNS RP) Supplementary report: blood folate results for the UK as a whole, Scotland, Northern Ireland (Years 1 to 4 combined) and Wales (Years 2 to 5 combined). These results were delayed from the main NDNS year 1-4 report that was published in May last year.

The report presents results for serum total folate, red blood cell folate and free (unmetabolised) folic acid concentrations for the standard NDNS age/sex groups and for women of child-bearing age, broken down into three age sub-groups (16-24 years, 25-34 years and 35-49 years and presented as a whole for 16-49 years). Data on blood folate concentrations is presented separately for Scotland, Northern Ireland and Wales and comparisons are made with the UK as a whole. However, due to small sample sizes, results are not presented for all age/sex groups in Scotland, Northern Ireland and Wales.

Below is a brief summary of the findings from the 43-page report.

Serum total folate

UK as a whole

  • A substantial proportion of adolescents aged 11-18 years (16.9% of boys and 21.8% of girls) had serum total folate concentrations below the World Health Organization (WHO) threshold indicating folate deficiency (10 nmol/L). There was also evidence of deficiency in 14.7% of adults aged 19-64 years (15.5% men, 13.9% women) and 10.8% of adults aged 65 years and over (8.5% men and 12.4% women).
  • Less than 3% of children aged 4-10 years had a serum total folate concentration below 10nmol/L.

Red blood cell folate

UK as a whole

  • Substantially more girls (19.7%) than boys (9.3%) aged 11-18 years had a red blood cell folate concentration below the WHO threshold indicating biochemical folate deficiency (340 nmol/L). By comparison, 6.8% of men and 8.6% of women aged 19-64 years and 7.3% of men and 10.8% of women aged 65 years and over had a red blood cell folate concentration lower than 340 nmol/L.
  • Less than 4% of children under 11 years of age were below the threshold for deficiency.

Results for women of childbearing age (16-49 years)

UK as a whole

  • Evidence for an increased risk of folate deficiency was found for a considerable proportion of women of childbearing age. Serum total folate deficiency was highest in women aged 16-24 years (22.1%), followed by women aged 25-34 years (17.7%) and 13.1% of women aged 35-49 years.
  • The percentage of women of childbearing age with a red blood cell folate concentration below 340 nmol/L was highest among those aged 16-24 years (15.6%) and lowest for those aged 25-34 years (9.5%).

Scotland, Northern Ireland and Wales

  • A greater proportion of women of childbearing age (16-49 years) had serum total folate below the WHO threshold in Scotland (24.4%) and Northern Ireland (30.6%) compared to the UK as a whole (16.5%). The figure for Wales was not significantly different (14.5%).
  • The proportion of women of childbearing age (16-49 years) who had red blood cell folate concentrations below the WHO threshold for deficiency was greater in Scotland (14.8%) and Northern Ireland (20.2%) compared to the UK as a whole (11.3%). The proportion was slightly lower in Wales (10.3%).

Results for Scotland, Wales and Northern Ireland and comparisons with the UK as a whole

Serum total folate

  • Serum total folate concentrations were significantly lower in adults aged 19-64 years in Scotland and Northern Ireland compared to the UK as a whole.
  • In Wales, the value was significantly lower for adults aged 65 years and over, but the proportion below the WHO threshold of 10 nmol/L was similar (12.4% in Wales vs 10.7% in the UK as a whole).

Red blood cell folate

  • In Scotland, a greater proportion of women aged 19-64 years (13.9%) and adults aged 65 years and over (16.5%) were below the WHO threshold for deficiency compared to the UK as a whole (8.6% and 9.3% respectively).
  • In Northern Ireland, mean red blood cell folate concentration was significantly lower among women aged 19-64 years and adults aged 19-64 years (males and females combined) compared to the UK as a whole.
  • There were no significant differences between Wales and the UK as a whole for any age group.

Implications for health

Folate functions together with vitamin B12 to form healthy red blood cells. It is also required for normal cell division, the normal structure of the nervous system and specifically in the development of the neural tube (which develops into the spinal cord and skull) in the embryo. Folate is found in fruits like oranges and berries, green leafy vegetables and legumes. Folic acid, the synthetic form of folate, is found in fortified breakfast cereals and dietary supplements.

Deficiency can lead to folate deficiency anaemia, and may cause tiredness, shortness of breath, a sore tongue and depression. The high prevalence of folate deficiency in adolescents, particularly among girls and young women, is particularly concerning. Folate requirements are increased during pregnancy, hence a considerable number of women may enter pregnancy in a deficient state, which increases the risk of pregnancy complications and birth defects. It is difficult to meet the increased folate requirements during pregnancy from food alone, and so all women of childbearing age who are planning a pregnancy are recommended to take a supplement of 400 µg folic acid per day (and should continue to take this for the first 12 weeks of pregnancy) to prevent neural tube defects in the baby.

In 2006 SACN made a recommendation for mandatory fortification of flour with folic acid to be introduced in the UK as a means of increasing folate intakes of women most at risk of NTD affected pregnancies, as well as other population groups in the UK with low intakes, provided voluntary fortification is controlled and advice is given about supplement use (to avoid intakes exceeding the safe upper level in high consumers). This recommendation is currently with health ministers and a decision is yet to be made.