Folate Status in New Zealand: Does Yeast Extract Spread Make a Difference?
Culture influences food choices and nutrient status at the population level. Even in countries that share cultural roots, there can be marked differences in the consumption of certain foods. New Zealand is a prime example, where recent shortages in supply of the Kiwis own beloved brand of yeast extract spread lead to a “crisis” situation. The consumption of yeast extract spread on bread or toast is not only a quaint undertaking by antipodeans, as the high levels of B-vitamins that are consumed with the spread can be of public health significance.
New Zealand has a voluntary system of bread and cereal fortification, and a mandatory fortification scheme set to start recently was cancelled last year, according to authors Bradbury and colleagues in a recently released publication in the Journal of Nutrition. In addition to fortified foods, other foods also contain folate: foods such as beef liver, spinach, black-eyed peas and New Zealand’s favorite yeast extract spread containing more than one quarter of recommendations for adults. The authors wanted to conduct a representative study of New Zealanders to determine their folate status and potentially identify factors that influence folate levels.
Around three thousand participants had their serum folate and red blood cell folate levels measured. Other socio-demographic variables and a 24-hour dietary recall were collected. Serum folate gives an estimation of recent folate consumption (in the previous few days) while red blood cell folate provides a longer term view on folate status. The authors of the present study used cut-off levels of 6.8 nmol/L for serum folate, and 305 nmol/L for red blood cell folate to determine risk of deficiency. These cut-offs are suitable for estimating the proportion of the population with clear deficiency, however based on a review of measures of folate status by Green, serum levels of 16 nmol/L are associated with the greatest reduction in risk of neural tube defects, 340 nmol/L red blood cell folate is the cut-off for sub-clinical folate deficiency, and 900 nmol/L red blood cell folate shows the greatest reduction in neural tube defects. Although only 2% of New Zealanders had folate levels indicative of frank deficiency, using the higher cut-off points indicate that around one third of the population has levels lower than what is recommended to prevent neural tube defects. The authors unfortunately do not present the results for target population for folate fortification, women of childbearing age. As only 7% of New Zealand women take folic acid supplements immediately prior to conception, and only 54% during pregnancy according to a study by Arroll, the baseline folate status of this risk group is important.
Some trends were found in the data. There are some ethnic differences in folate concentration such that New Zealanders of European descent have higher folate levels than Maoris, who have higher levels than Pacific Islanders. Risk of deficiency was also higher for Maoris and Pacific Islanders. Older New Zealanders tended to have a better folate status. For every unit increase in body mass index, folate concentration in serum decreased by 1%. Smoking reduced folate concentrations by 10%, while eating breakfast cereal increased serum folate by 6% for each day of the week it was consumed (breakfast cereal is often fortified with folate in New Zealand). Use of folate-containing supplements was, not surprisingly, correlated with higher folate levels. Interestingly, people who reported consuming yeast extract spread during the 24-hour dietary recall had a 17% higher serum folate and 14% higher red blood cell folate concentration. This was considered to be a conservative estimate as people who normally consume this product may not have consumed it on the day of the 24-hour dietary recall, therefore they may have been included in the group with the non-consumers.
This study is important as it sets a baseline for folic acid levels in the New Zealand population. Future analyses should also include the population of women of childbearing age (especially by ethnicity and socio-economic status) to ensure that are appropriate to prevent neural tube defects.
Kathryn E. Bradbury, Sheila M. Williams, Jim I. Mann, Rachel C. Brown, Winsome Parnell, and C. Murray Skeaff. Estimation of Serum and Erythrocyte Folate Concentrations in the New Zealand Adult Population within a Background of Voluntary Folic Acid Fortification. J. Nutr. 2014 jn.113.182105; first published online October 30, 2013. doi:10.3945/jn.113.182105
Arroll N, Farquhar C, Sadler L, Stone P, Masson V. Can we improve the prevention and detection of congenital abnormalities? An audit of early pregnancy care in New Zealand. N Z Med J. 2013 Aug 16;126(1380):46-56. http://www.ncbi.nlm.nih.gov/pubmed/24126749
Green R. Indicators for assessing folate and vitamin B-12 status and for monitoring the efficacy of intervention strategies. Am J Clin Nutr. 2011 Aug;94(2):666S-72S. doi: 10.3945/ajcn.110.009613. Epub 2011 Jul 6. http://www.ncbi.nlm.nih.gov/pubmed/21733877