Folic Acid

Understanding Bioavailability

If you try to learn about folic acid and folate, you will eventually run across the term ‘bioavailability’. Specifically, many articles on folic acid or folate say that folic acid has a higher bioavailability than folate. What does bioavailablity mean? How does it affect you? And does it matter for people with MTHFR anomalies?


What is bioavailability?

Digestion is the process of breaking down food so it can be absorbed and used by the body. Acids in the stomach and other chemicals in the intestines turn a bite of spinach, a vitamin supplement, or a handfull of french fries into basic nutrients, vitamins and carbohydrates that can be absorbed into the body through the intestines.

During this process, many of the nutrients and chemicals that make up our food are split into smaller chemicals or changed in other ways. Some nutrients or chemicals don’t get absorbed – they pass through the intestines and are carried out as wastes. This means that sometimes you can eat what should be enough of a nutrient, but still not get enough of it.

In addition to whether or not a nutrient or chemical gets absorbed into the body, different chemicals are absorbed into the body at different rates. This is why some medicines take hours or days to take effect – if they are absorbed slowly, you won’t see any benefit until enough has been absorbed to begin making a difference.

Bioavailability is the combination of how much of a nutrient gets absorbed, and how quickly it gets absorbed. However, when talking about nutrients like folic acid and folate, bioavailability mainly refers to how much gets absorbed. So when an article talks about folate having less bioavailability than folic acid, it means that if you take 100 mg of folate, and 100 mg of folic acid, your body will actually get more folic acid than folate.


How Does Bioavailability Affect Me?

For the most part, bioavailability of any nutrient or medicine won’t affect you. The recommended daily amounts of nutrients take into account their bioavailability, so as long you take the recommended amount, you should get the right amount of the nutrients actually in your bloodsteam. Doses for medicine are also based on bioavailability.

Bioavailability does vary a bit from person to person – things like age, gender, diet and lifestyle can have an impact on how much of a nutrient your body actually absorbs. For this reason, the general RDA for a nutrient is a bit higher than most people actually need, so people with lower bioavailability for certain nutrients can still get enough. If you want to be sure you are getting enough of a nutrient, you can check out the specific recommended intake for your demographic or talk with a nutritionist.

When you are making sure you get enough folates, bioavailability becomes more important. The RDA for B9 is set based on folic acid. If you are getting most of your B9 through folates in your food, you need to take more than the RDA for folic acid in order to get enough. How much more? No one really knows. Studies on folate bioavailability have had a wide range of results. This is probably because different folates have different bioavailability rates, and because diet has a huge impact on how your body absorbs folates.

There are other issues with getting enough folates, but as far as bioavailability goes its probably a good idea to try and get at least twice as much folate as the RDA for folic acid.


How is Bioavailability Important for People with MTHFR Anomalies?

For people with MTHFR anomalies, natural folates that their bodies can use properly are often a better source of B9 than folic acid. The lower bioavailability of folate, plus other problems with folate intake, can make getting enough folate challenging. It is very important for people with MTHFR anomalies who choose to get their B9 through folate know that they need to get folate than the RDA of folic acid, and how to change their diets to maximize their folate intake.

Folic Acid FAQs

What is folic acid?

Folic acid is a man-made form of vitamin B9. Folic acid is more stable and easier for the body to absorb than naturally occurring forms of B9. However the body can’t use folic acid directly, it needs to convert it into different folate forms in order to use it.


What is folate?

Folate refers to several different naturally occurring forms of vitamin B9. Folate is unstable and difficult for the body to absorb. The body can use folates more easily than folic acid, but it is difficult for the body to get enough folate.


So is folic acid or folate better?

Tough question. For people who do not have MTHFR, it’s not a bad idea to take folic acid supplements. You can be sure you are getting enough in any over the counter supplement, and your body is able to convert it without too much trouble. However, only women who are able to get pregnant need to take folic acid supplements regularly in the US. Folic acid is regularly added to bread, rice, and pasta, in the US, so you are probably getting enough folic acid in your normal diet.

For people with MTHFR anomalies, folate is better if you can get enough of it. Your body will be able to use the folate more easily and you will get more benefits from it. The difficulty is in getting enough folate. If you can’t get enough folate, or aren’t sure if you are, you can take larger folic acid supplements. Even if the MTHFR anomaly keeps your body from using most of the folic acid, if you take enough of it, your body will be able to do everything it needs to. Unfortunately, taking too much folic acid may cause other problems, so don’t take more than 1000mg a day, and try to get your B9 from other sources of folate as much as possible.


What are the sources for folic acid?

In the US, and several other parts of the world, folic acid is added to staple foods like bread, rice and pasta. If you don’t have a metabolic problem interfering with folic acid (like MTHFR) you can get enough folic acid just by eating a healthy diet. If you follow a low carb diet, you may want to take folic acid supplements. Folic acid is a manmade version of folate, and is not found naturally in foods.


What are sources for folate?

The best sources for folate are beef liver, bean and legumes, and green vegetables. However, folate in green vegetables degrades quickly – raw vegetables will have more folate than cooked, but vegetables will lose folate if they are stored to long, exposed to light after being cooked, or well, pretty much anything other than eaten right away. Dried beans and legumes do not lose folate in cooking or storage.

What is L-methylfolate?

L-methylfolate is a stable form of folate that is extremely bioavailable – the body is able to use it more effectively than any other form of folate. At the moment, L-methylfolate is only available by prescription. It is the best form of folate for people with MTHFR anomalies.

Why do I need folic acid?

People who do not get enough folate will develop a folic acid deficiency. Symptoms include:

  • Increased risk of neural tube birth defects and miscarriage

  • Slow growth in infants and children

  • A form of anemia

  • Digestive disorders

  • Weakness

  • Sore tongue

  • Headaches

  • Irritability

  • High levels of homocysteine

How much folic acid do I need?

Most adults need 400mg of folic acid daily, usually you can get this through your diet. Pregnant woman, people with high alcohol intake, people with liver problems, and anyone taking a medication which interferes with folic acid absorption should take more.

Will folic acid supplements help with problems caused by MTHFR anomalies?

Possibly. MTHFR anomalies reduce the effectiveness of folic acid in the body. If you have an anomaly that reduces the bodies ability to use folic acid by 50%, than taking 800mg a day rather than 400mg should prevent the health problems MTHFR can cause. If you have an anomaly that reduces the body’s ability to use folic acid by 90%, than when you take 400mg, your body only uses 40mg. You’d need to take 4000mg of folic acid each day in order to get what you need. While folic acid isn’t toxic, this would leave over 3000mg of unused folic acid in your body, and some studies have found potential problems from excess folic acid in the blood stream.

If you have a severe version of MTHFR, you are better off learning how to get folate from your diet or getting a prescription for L-methylfolate.