Contents
Folate equivalents
The term “folates” covers a group of compounds with minor differences in chemical structure. However, all these compounds exhibit the properties of vitamin B9. It is assumed that the deadline folates are those compounds that are contained in foodand the relationship contained most supplements contain folic acidwhich is a permanent and stable form of vitamin B9. Methylfolate (or actually methyltetrahydrofolate) has also appeared on the market of dietary supplements, which is an active form of vitamin B9, however, with lower stability compared to folic acid.
Depending on the structure of the compound belonging to the folate group, it may have a different bioavailability. What does this mean in practice? Namely, that we can consume fewer folates than others in order to have the same biological effect. It turns out that the more accessible form for our cells is folic acid (compared to folate). This is because in order for the folates contained in food to be absorbed, they must first undergo some transformation, while the folic acid is immediately “ready” to be absorbed.
For this reason, the term folate equivalent (RF) has been introduced, which is a kind of universal unit for expressing the amount of bioavailable folate consumed with certain sources. And so, 1 µg of folate equivalent is the same as 1 µg of folate contained in food, at the same time the same as 0,6 µg of folic acid consumed with food enriched with this ingredient and as much as 0,5 µg of folic acid consumed in the form of a supplement on fasting. In other words, if we consume 200 µg of folate with food, it means we are providing 200 µg of folate equivalents, while if we consume 200 µg of folic acid in the form of a supplement, it is like delivering 400 µg of RF to the body.
What are folates needed for and who are they important to?
The role of folates comes down mainly to transferring one-carbon groups to different acceptors. These reactions are called methylation, and the active form of folate capable of carrying this group is methyltetrahydrofolate (methyl-THF) (this form is now available in some supplements). It is formed in the body from various forms of folate in the course of biochemical reactions, the course of which is possible thanks to enzymatic proteins. One such protein that is crucial for the formation of methyl-THF is methylenetetrahydrofolate reductase, or MTHFR for short. The active form of folate is taken, among others, by participation in the methylation of homocysteine to methionine. Increased levels of homocysteine (so-called hyperhomocysteinemia) are associated with a higher risk of cardiovascular disease and neurodegenerative diseases. Folates are also involved in the synthesis of nucleic acids and proteins, so they are important for the growth of all body cells, and their deficiency can lead to megaloloblastic anemia and an increased susceptibility to the development of certain types of cancer.
Folates are also necessary in the processes of the formation of the myelin sheath on nerve fibers, which performs protective functions. In addition, they reduce the risk of birth defects associated with incorrect closure of the neural tube. Adequate intake of folate and their content in the body is also important for men, as supplementation with folic acid has been shown to have a positive effect on semen parameters.
How much folate do we eat and how much should we eat?
The consumption of folate in Poland varies between 200 and 300 μg RF, with higher consumption usually in men. Poles usually do not supplement themselves with folic acid – this applies only to about 15% of the population. It turns out that the amount of folate consumed by Poles is insufficient. Currently, the Food and Nutrition Institute (IŻŻ) recommends the consumption of folates in the amount of 400 μg RF for adults (regardless of gender). For pregnant women, it is recommended to consume 600 μg RF / day and for lactating women – 500 μg RF / day. In addition, the Polish Gynecological Society recommends supplementation with folic acid in a dose of 400 μg / day as early as 6 weeks before pregnancy.
The recommendations included in the FI standards assume that for most people (97,5% of the population) the demand will be covered, but for some people (2,5% of the population) the consumption of 400 μg RF / day will still be too low to cover the demand . This is because each of us has a different need for each nutrient, including folate. These differences result from different possibilities of metabolizing these compounds, which results from the activity of enzymes located, for example, in our cells. The structure of each enzyme is stored in DNA, therefore certain changes in its sequence (so-called polymorphisms) may result in our body “producing” an enzyme with a structure different than the average. For example, it is known that polymorphism in the 677 nucleotide pair of the gene encoding the MTHFR enzyme, which is the replacement of cytosine (C) with thymine (T), results in the synthesis of the enzyme with a lower activity. Therefore, it is recommended that people with the TT genotype consume 600 µg RF / day.
However, be careful not to overdo the amount of folate consumed during the day. Their maximum dose, which is not associated with any side effects (e.g. masking vitamin B12 deficiency), the so-called the tolerable upper intake level is 1000 µg RF / day. Such large doses of folate can actually only be consumed with supplements or large amounts of folate-fortified foods.
Although there have been reports that high doses of folic acid may increase the risk of some cancers, it now seems that this relationship is not so simple to explain. Probably supplementation with folic acid can intensify cancer formation if abnormal cells are already present, while an appropriate state of saturation of the body with folates can prevent the formation of cancer.
Folates can be found primarily in green vegetables, cereal products and some fruits. The exact folate contents of the commonly consumed serving sizes are shown in the table below.
| group of products | Product | folate content [µg/100g] | consumed portion | approximate folate content [µg / portion] |
| legumes | soybean | 280 | 30 g (about 1/4 cup) | 80 |
| seeds of other legumes (broad beans, beans, chickpeas, lentils) | 150-180 | 30 g (about 1/4 cup) | 50 | |
| tofu | 20 | 90 g (1/2 cube) | 20 | |
| vegetables and fruits | vegetables with a very high folate content: parsley, spinach, asparagus | 150-200 | 80 g (approx. 1 cup) | 150 |
| vegetables with a high folate content: Brussels sprouts, kale, broccoli | 100-150 | 80 g (approx. 1 cup) | 90 | |
| vegetables with an average folate content: cabbage, lettuce, beets, green beans, green peas, avocado, cauliflower, zucchini, chicory, corn, pepper | 50-100 | 80 g (approx. 1 cup) | 60 | |
| fruits: kiwi, papaya, mango, melon, raspberries, oranges | 30-40 | 80 g (approx. 1 cup) | 30 | |
| Orange juice | 24 | 250 ml (1 glass) | 15 | |
| nuts and seeds | nuts (e.g. walnuts, hazelnuts), pumpkin seeds, sunflower seeds | 70 | 30 g (handful) | 20 |
| peanuts | 110 | 30 g (handful) | 30 | |
| grain products | oatmeal, muesli | 80 | 30 g (2 tablespoons) | 20 |
| bread, cereal, rice | 30 | 30 g (1 slice, 2 tablespoons before cooking) | 10 | |
| pasta | 40 | 40 g (1/2 cup before cooking) | 20 | |
| eggs and dairy products | Yeah yeah | 65 | 60 g (1 piece) | 40 |
| blue cheeses (e.g. camembert) | 60 | 30 g (1/4 disc) | 40 | |
Unfortunately, folates are very sensitive to thermal treatment and their losses can range from 10 to 95%. Higher losses are observed at higher temperatures and during boiling in water, as some folates are washed away by water. For this reason, it is worth consuming sources of folate in unprocessed form.
It is also worth remembering that a certain source of folate for humans are bacteria in the intestines, because they have the ability to synthesize this vitamin. It is estimated that the bacteria present in our intestines can provide up to 37% of our needs for this vitamin. The amount of produced vitamin depends, however, on the species composition of the microbiota, and this, among others, on our diet. Usually, the more our diet corresponds to the nutritional recommendations, the more diversified the microbiota, and this is associated with a positive impact on human health.
Practical tips or how to increase folate intake?
- Don’t give up on bread and other grain products. 10 servings of these products can cover 30% of your needs.
- Eat plenty of vegetables and fruits, preferably raw.
- Choose mostly green vegetables such as spinach, Brussels sprouts and broccoli. 2 portions of such vegetables will cover about 50% of your needs.
- A few times a week, replace the meat dish with the legume seed dish – you will find a lot of folate in them, unlike meat. Such a lunch portion will cover over 25% of your needs.
- If you are planning a pregnancy – consider supplementing with folic acid.
Bibliography:
1. Suitor CW, Bailey LB. Dietary folate equivalents: interpretation and application. J Am diet Assoc. 2000;100(1):88-94
2. Delchier N, Herbig A-L, Rychlik M,. Renard CMGC. Folates in Fruits and Vegetables: Contents, Processing, and Stability. Comprehensive Reviews in Food Science and Food Safety 2016;15(3):506-528
3. Magnúsdóttir S, Ravcheev D, de Crécy-Lagard V, Thiele I. Systematic genome assessment of B-vitamin biosynthesis suggests co-operation among gut microbes. Front Genet. 2015 20;6:148
4. Field MS, Stover PJ. Safety of folic acid. Ann N Y Acad Sci. 2018;1414(1):59-71
Picture:
https://www.pexels.com/photo/vegetarian-juice-on-t…
Anna Malinowska, the author of this article, is a PhD at the University of Life Sciences in Poznań and runs the Microflora-Diet-Metabolism research project, in which she studies the impact of nutrition on the intestinal microbiota and, inter alia, on the potential of the gut microbiota to metabolize dietary fiber and cholesterol.