B Vitamins: Where Quality and Quantity Collide

B Vitamins: Where Quality and Quantity Collide

Bioavailable B Vitamins

You’ve done your research and you’re on the lookout for the best in Bs in all of the supplements you’re taking. You might not completely understand why, but you know that B vitamins are a critical component when it comes to supporting conception, pregnancy, and breastfeeding.

In my private practice, I often hear from clients who have been advised to look for a supplement with "methylated B vitamins" (often referred to as "active B vitamins"). This is great advice! But understanding why and diving into the research and reasoning behind that advice is important. 

Especially during pregnancy and while breastfeeding, I challenge you to look for the most bioavailable form of B vitamins you can get your hands on. Why are bioavailable Bs so important? Let’s take a closer look.

First of all, what is bioavailability? 

“Bioavailability” is the readiness with which a food or drug is able to be absorbed into the bloodstream. 

High bioavailability = very easily/quickly absorbed
Low bioavailability = ...not so much 

When something is not bioavailable, it is perhaps in a form that must be altered or converted to another form in order to become more readily used. The extra step (and sometimes steps) involved in that conversion causes the body’s metabolism of the nutrient to be much slower and less efficient overall. Not ideal, especially during pregnancy when your body is working hard to make an entirely new human being. 

In the case of vitamin B12 and folate, the methylated forms do not require a key enzyme in order to restructure it and make it more bioavailable, which makes them more inherently efficient. This is good news, because there are many people who have a MTHFR genetic SNP mutation, which makes it difficult to produce sufficient amounts of the enzyme needed to convert non-methylated forms. 

That suddenly got a little complicated, so let’s back up.

All of us possess a gene called 5-methyltetrahydrofolate, commonly abbreviated to MTHFR (I know it looks odd, bear with me). MTHFR stands for methylenetetrahydrofolate reductase, which is an enzyme that plays a role in processing amino acids. In the case of B vitamins, it converts non-methylated forms into more bioavailable molecules that are easily put to work in the body. Specifically, MTHFR is responsible for the breakdown of folic acid (B-9), which creates folate. Folate plays an important role in red blood cell formation and is vital for healthy cell growth and function.  

When someone possesses a MTHFR genetic SNP mutation (which again, is not completely uncommon), their body has a hard time making the methylenetetrahydrofolate reductase needed to convert non-methylated B vitamins into more easily processed forms. A less efficient MTHFR gene results in an inability to produce enough MTHFR, which causes low levels of folate and other vitamins in the blood. Folate is critical for This can put expectant mother’s, especially in the first few weeks of pregnancy, as it plays an important role in creating red blood cells and helps baby’s neural tube develop into their brain and spinal cord.

Not on our watch!

With highly bioavailable, methylated B vitamin varieties, the extra step that requires methylenetetrahydrofolate reductase is completely eliminated or reduced, making the process more efficient and therefore better for the population at large. After all, how many of us know the status of our MTHFR? Unless you’ve run some pretty comprehensive lab work with your doctor, there’s no way to know whether or not your DNA holds this mutation or not. That’s why supplementing with the methylated B vitamins is so important.

What is FullWell Prenatal's solution to providing “active” or “bioavailable” B vitamins?

FullWell Prenatal expertly combines methylcobalamin, adenosylcobalamin, and methyltetrahydrofolate with calcium folinate (folinic acid) to provide enough active B vitamins while also reducing side effects that affect tolerance. 

Side effects?!

When it comes to B Vitamins, you can have too much of a good thing.

While B vitamins as a whole can support mood, sleep, and can reduce pregnancy-induced nausea, flooding the body with high doses can have some serious consequences. Overmethylation can lead to increased anxiety, which is something I’ve experienced firsthand from working with expectant mothers in my private practice as a Registered Dietitian and functional nutritionist. Women definitely don’t need any extra stress while they are pregnant and already going through so many physical, mental, and emotional changes, so this is one of the first things I addressed while creating FullWell.

The breakdown

I formulated FullWell with folate, B-12, and B-6 in forms that are both highly bioavailable and are widely researched (safety first, always). When you take your FullWell Prenatal Vitamins, not only are you ingesting your B vitamins in the forms that are easiest to digest, absorb, and utilize, you are getting an ideal amount and balance to support your growing baby without experiencing any of those aforementioned, unnecessary side effects.

Based on my research and experience, I chose to avoid folic acid, opting instead to combine methylated forms (methyltetrahydrofolate, the methylated form of folic acid) with other active forms (calcium folinate) to increase tolerance and avoid overdoing it.

The blend:

  • 80% methylfolate, 20% calcium folinate (folinic acid) 
  • 1:1 blend of methylcobalamin and adenosylcobalamin

The above provides you with a highly bioavailable supplement that is combined with specific ratios of non-methylated forms to strike the right balance and avoid overmethylation. 

If too much B sparks side effects, why does FullWell contain so much B-12?

Ok, so you now understand why quality and form matter, but I’ve really only scratched the surface on quantity as it pertains to pregnancy.

B-vitamins are water-soluble and rely on optimal digestive functioning to be absorbed well. Research shows that only about 10 mcg of a 500 mcg oral Vitamin B12 supplement is actually absorbed in non-pregnant, healthy people. This is one of the reasons why FullWell Prenatal's B-12 levels exceed the percent daily value for the average, non-pregnant person. (It's worth noting that some studies show that vitamin B-12 intake in pregnancy should be at least triple the current RDA.)

More than half of all women have suboptimal levels of vitamin B-6 at delivery. So, while the balance of forms is essential, it is extremely challenging to overdo it on B vitamins while pregnant. 

Where does vitamin B come from?

When it comes to your diet, B vitamins are most abundantly found in animal foods. Animal-based products provide key nutrients that simply cannot be found anywhere else, which is why I am such a proponent of incorporating them into my clients’ diets and lifestyles when I work with them one-on-one.

Animal products full of B vitamins

  1. Salmon
  2. Liver (and other organs)
  3. Milk
  4. Eggs
  5. Beef
  6. Oysters
  7. Clams
  8. Mussels
  9. Chicken
  10. Turkey
  11. Yogurt
  12. Pork
  13. Trout

A side note on food safety

Remember that food safety during pregnancy is especially imperative to protect the health of both mom and baby as well as managing pesky food-related symptoms. 

Quick, easy ways to make sure your animal products are safe for pregnancy:

  • Fish | the nutrient benefits of fish likely exceed heavy metal and contaminant concerns, but you can assuage your fears by choosing brands like Safe Catch who only work with fisherman who catch from managed and sustainable stocks
  • Shellfish | avoid eating raw and instead opt for cooked or smoked varieties
  • Meat & poultry | defrost meat in the refrigerator overnight (as opposed to on the counter at room temperature), and only store in the fridge for 2-3 days

What if I choose not to consume animal products?

Vegans or vegetarians should be vigilant about vitamin B intake, which makes informed, wise supplementation that much more important. However, avoiding animal products doesn’t mean you can’t make a valiant effort to consume B’s through your diet.

Vegan and vegetarian mamas will need to focus on eating

    1. Dark leafy greens | spinach, collard greens, turnip greens, romaine
    2. Legumes | black, kidney, garbanzo, and pinto beans, lentils, greens peas, edamame, roasted soy nuts
    3. Sunflower seeds and sunflower seed butter
    4. Supplements | It’s imperative that vegan women supplement with extra B vitamins, particularly vitamin B12 both in and outside of pregnancy 

How important are B Vitamins?

B vitamins are essential for maintaining physical strength during pregnancy and supporting the baby’s development and growth. Getting enough B12 helps:

  • Assists in metabolizing carbohydrates, proteins, and fats, and this improves your mood and energy levels
  • Plays a major role in your baby’s brain development and neural tube formation
  • Supports healthy blood pressure levels
  • Supports carrying your baby to term

Breastfeeding mothers also benefit from enough vitamin B12, since it can be transferred through breast milk to breastfed babies. This is essential and needed for baby’s overall growth and development.

A final thought

Lastly, I’d like to address concerns on recent research that has linked high vitamin B-12 intake to autism in children. This is a question that I’ve been asked a lot, and for good reason. The important thing to know is that in these studies, the form of vitamin B-12 being used was cyanocobalamin. After reading this blog post, you now know why the form of the nutrient matters so significantly! We do not use cyanocobalamin (which requires enzyme facilitated conversion in the body) in FullWell Prenatal. It is also worth noting that these studies show a correlation, but are far from definitive. There are likely many factors and variables that we do not yet know or understand that lead to autism. The very best you can do is keep your body well nourished with optimal forms and doses of nutrients.

Are you taking your full serving of FullWell Prenatal(First Trimester mamas, you get a pass, just do your best!) 

*The information provided on this website is provided for educational purposes only and should not be treated as medical advice. FullWell makes no guarantees regarding the information provided or how products may work for any individual. If you suffer from a health condition, you should consult your health care practitioner for medical advice and before introducing any new products into your health care regimen. For more information please read out terms and conditions.


  1. "MTHFR gene methylenetetrahydrofolate reductase." U.S. National Library of Medicine. Web. 12 Mar. 2021. https://medlineplus.gov/genetics/gene/mthfr/.
  2. Arnarson, Atli BSc, PhD. "Folic Acid vs. Folate — What’s the Difference?" Healthline. 19 Aug. 2019. Web. 12 Mar. 2021. https://medlineplus.gov/genetics/gene/mthfr/.
  3. "Folate (Folic Acid)." The Mayo Clinic. Web. 12 Mar. 2021. https://www.mayoclinic.org/drugs-supplements-folate/art-20364625.
  4. “Six Possible Side Effects Of Vitamin B Overdose.” Medicover Hospitals. Web. 12 Mar. 2021. https://www.medicoverhospitals.in/vitamin-b-overdose/.
  5. McCulloch, Marsha, MS, RD. "15 Healthy Foods High in B Vitamins." Healthline. 11 Oct. 2018. Web. 12 Mar. 2021. https://www.healthline.com/nutrition/vitamin-b-foods.