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.

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