"The findings are concerning because they show that public health interventions aren't always effective in reaching vulnerable populations who need them the most," said Tina Cheng, M.D., M.P.H., co-director of Johns Hopkins Children's Center and the study's lead author.
The report was published in April in the American Journal of Public Health.
Minority populations were most vulnerable
Her team looked at more than 7,000 low-income mothers enrolled in the Boston Birth Cohort, which was initiated in 1998 at the Boston Medical Center.
The sample population was predominantly black (50.3%) or Hispanic (26.6%), reflecting the racial make-up of US urban, low-income populations.
The researchers analyzed folate concentrations in the mothers’ blood as well as their intakes of folate—an important nutrient for maternal and infant health because previous studies have linked an insufficiency of folate to neural tube defects.
Black and Hispanic mothers had lower plasma folate concentrations than white mothers, who had an average of 34.2 nanomoles per liter.
Black and Hispanic mothers also had higher rates of folate insufficiency (defined as plasma folate concentration less than 13.5 nanomoles per liter based on World Health Organization criteria), at 12.2% and 8.1%, respectively, than white mothers, who had a 5.1% rate of insufficiency.
Linked to the average US diet—room for supplements to come in?
The researchers found that cohort participants who have lived in the US for less than 10 years were more likely to have higher folate concentrations.
It was especially the case for Hispanic mothers, where foreign country of origin was associated with higher folate concentrations. This suggests that the average US diet may lead to insufficient folate levels, a nutrient found in leafy greens and liver.
Commenting independently on the study, Duffy MacKay, senior vice president of scientific and regulatory affairs for the dietary supplements trade group Council for Responsible Nutrition, said that the findings by Cheng and her team reflect a wider trend in the US.
“This is absolutely true for the entire nation as evidenced by the thorough scientific evaluation and ‘Grade A’ recommendation from the US Preventive Services Task Force (USPSTF),” he told us.
“In 2018, well into the period of folic acid fortification that started in 1998, the US Preventive Services Task Force (USPSTF) updated its recommendation on folic acid supplementation in women of childbearing age,” he added.
Within USPSTF’s ‘Grade A’ recommendation, the task force recommends that all women who are planning or capable of pregnancy take a daily supplement containing 0.4 to 0.8 mg (400-800 µg) of folic acid, MacKay explained.
“So in addition to the fortified food that is consumed, USPSTF still recommends supplementation for all women (including all income levels).”
Increasing access to folate/folic acid intake
The research team found that, of the 7,000 plus mothers, only 4.3% took folic acid supplementation almost daily preconception, a widely recommended public health measure designed to prevent potentially crippling birth defects.
Cheng pointed out that the findings are an important step forward toward understanding folate supplementation and levels in vulnerable populations, as well as informing strategies going forward to reduce health disparities.
To MacKay, the findings suggest that more intervention may be needed. “The current folic acid ‘public health intervention’ are FDA food fortification laws that started in 1998. Food fortification is important, but it is dependent on an individual consuming an adequate amount of the fortified food,” he said.
“If an individual does not eat the fortified food regularly, food fortification does not work. A much more specific way to ensure adequate folic acid during childbearing years is to take a dietary supplement containing the targeted amount of folic acid.”
CRN is among several trade groups that advocate for the inclusion of some supplements in welfare programs like SNAP and WIC.
“Low income Americans should be provided the same opportunities for health and vitality as all Americans. There are serious health consequences to nutrient short falls, especially folic acid during pregnancy,” MacKay added.
“Getting all essential nutrients from food is preferred, but this data show that many low-income women are falling short of folic acid. We should give these women a fair chance at a healthy pregnancy and this is why CRN supports legislation that would allow women who participate in the Supplemental Nutrition Assistance Program (SNAP) to use their benefits to purchase a multivitamin that would provide the recommended amount of folic acid daily.”
Source: American Journal of Public Health
2018 Jun;108(6):799-807. doi: 10.2105/AJPH.2018.304355. Epub 2018 Apr 19.
Authors: Cheng TL, et al.