Folates must necessarily be introduced through food as our body is unable to produce them. The reserves are limited and about half are found in the liver.
The amount of folate introduced by diet – if varied and balanced – is generally adequate, except in situations or periods of increased need (for example in anticipation of pregnancy or during pregnancy itself, particularly in the first months), during which supplementation with active folic acid is suggested.
The main food sources of folate are green leafy vegetables (spinach, broccoli, Brussels sprouts, asparagus, lettuce, turnip greens) from which the name of the vitamin derives, legumes (beans, peas), chickpeas, whole grains, artichokes, fresh fruit (kiwi, strawberries, oranges, avocado), dried fruit (almonds, walnuts, hazelnuts, peanuts) and brewer’s yeast. Some foods of animal origin, such as liver, offal and eggs, are particularly rich in folate, but should be consumed in limited and infrequent portions.
According to the Italian Society of Human Nutrition (SINU), the main sources of folate in the Italian diet are the following food groups: “Grains and derivatives” (29%), “Vegetables” (27%), “Fruit” (10%). Fortified foods (breakfast cereals, some baked goods (rusks, crackers), fruit juices) contribute to the average daily intake of adults in very limited percentages (<1%). (Source: LARN, SINU 4th Revision, October 2014).
The absorption of folate from the diet is variable and depends on the food source. Food preparation methods can also affect absorption: prolonged boiling, for example, inactivates much of the vitamin B9, which is a water-soluble vitamin, and therefore sensitive to heat, light, air and acidity. Individual factors and genotypes also influence the ability to absorb folate.
High consumption of alcohol depletes the reserves of folic acid and alters its absorption and use, as does the intake of some drugs, including analgesics such as acetylsalicylic acid, oral contraceptives, and antacids.
A reduction in the absorption of folic acid and/or a consequent increase in the requirement for it can also result from type 1 diabetes mellitus (insulin-dependent), celiac disease, malabsorption diseases or some specific variants of genes involved in the metabolism of folate (methylene-tetrahydrofolate-reductase, folate receptor).
