Vitamin B9 (or folic acid) is indispensable for certain bodily functions, particularly the production of genetic material. Below you will find information on its functions, the foods in which it is found and risks associated with too low or too high an intake.
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Updated on 22/03/2019
Vitamin B9 or folic acid
Presentation, food sources and nutritional needs
Definition, functions and roles
Folic acid or vitamin B9 plays an essential role in producing genetic material (DNA, RNA) and the amino acids necessary for cell growth, which explains why it is essential during the different stages of life. It plays an important role in the formation of red blood corpuscles, and the functioning of the nervous system (synthesis of neuromediators) and immune system. It is necessary for the production of new cells which makes it particularly important during intense periods of metabolic activity such as childhood, adolescence, and pregnancy (development of the fœtus). In France the mean incidence of neural tube defects which is a major consequence of a vitamin B9 deficiency in women in early pregnancy, is about 1 in 1000 pregnancies.
Foods that are rich in vitamin B9 and sensitivity of the vitamin
The foods that naturally contain the most vitamin B9 are liver, baker's yeast, egg yolk, shallot, leafy vegetables and soy "schnitzels".
The list of foods that is rich in vitamin B9 can be consulted via the Ciqual table at:
Folic acid is sensitive to air, light and heat especially in aqueous environments; boiling thus destroys a lot of it.
Population reference intakes
In 2016, the population reference intakes for folic acid in men and women over 18 years of age were reassessed at 330 µg/d, while for women in the periconceptional period (eight weeks before and after conception) they were assessed at 440 μg/d.
The previous reference intakes (French ANCs) for children ranged from 150 to 250 µg/d depending on the age group. Work is under way to re-assess these values.
Risk of deficiency and excess intake
Particularly because of the role of folic acid in synthesising DNA and RNA, a deficiency slows down the multiplication of cells, particularly cells which are normally renewed very frequently such as blood cells (red and white corpuscles), and those of the intestines, liver and skin. The signs of this hypovitaminosis are thus anaemia, digestive and neurological disorders and disorders of the mucous membranes (gums for example).
In pregnant women, the consequences of a folic acid deficiency are even more dramatic: anomalies in the development of maternal tissues (placenta, blood circulation) and fœtus (spina bifida, anencephaly), delayed growth of the fœtus, an increase in the risk of premature births, low folate reserves in infants. From adolescence, the female population should thus ensure that its needs for folic acid are met.
An intake of more than 1000 µg of folic acid per day must be supervised by a doctor as it might mask symptoms of a serious vitamin B12 deficiency, which could lead to irreversible neurological damage.