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Do B Vitamins Give You Cancer?

In this article you will learn:

  • What the positive research says about B vitamins

  • What the negative research says about B vitamins

  • How to interpret all of this information

  • Where to find quality B vitamin products and why

Lazy reader's section:

B vitamins are essential nutrients that provide your body with the building blocks for growth. Because cancer cells also need B vitamins to grow, in some situations it may be warranted to do further research and monitor your levels closely. It depends on the type of cancer, and also it seems that having high-risk behaviors (like smoking or drinking excessively) while combined with high intake of B vitamins may increase the likelihood. Taking the right forms of vitamins is also always important, because if your genes can't process the nutrients they may accumulate.

My three top picks in this area are: Methyl B (a B complex supplement), Sublingual B12 (a bioavailable B12 liquid) and P5P (a bioavailable form of B6).

The Details:

Some recent research about B vitamins has emerged that warrants discussion as you

supplement, test and work to align your body with a complete nutrition program. This body of research concerns the specific vitamins B6, B9 and B12 and their potential impact on DNA methylation and cancer.

The general idea is that high circulating levels of these vitamins may contribute to an increased likelihood of cancer, since they are implicated in energy production and

other important growth pathways. Because you can achieve these levels with supplementation, some research has come out that is pretty scary and confusing about how to go about when using these vitamins.

As always, it’s important to take everything with a grain of salt. My goal here in this article will be to present you with some of what’s been done in this area as well as a discussion so you have clarity on how to proceed in your own life and routine.

Positive Research

1. A study following almost 28,000 women for over 4 years found that B6 levels, both in the diet and in the blood, were inversely related to breast cancer risk. This means that the higher the levels were the more reduced the risk was.(1)

2. A study following 600 men for several years found that those with the highest levels of B6 in their blood had nearly half the risk (50% less) of non-small cell lung cancer than those with the lowest levels.(2)

3. A study following 38,000 women over age 45 for 10 years found that supplementing with folate (B9) or B6 did not affect colorectal cancer risk, but that dietary intake (or rather, lack thereof) was inversely and significantly related to this type of cancer risk. In other words, deficiency in B9 and B6 was a risk factor for colorectal cancer in this population.(3)

4. Another study saw similar results with the protective effects of B6 on colorectal cancer, but notably much more significantly in those who did not drink alcohol.(4)

5. Older research in the late 1970’s showed that B6 was effective at reducing the recurrence of bladder cancer.(5)

6. A study using megadoses of vitamins A, C, E and B6 (at 100mg), along with immunotherapy, showed that the megadose group had a significantly reduced recurrence of bladder cancer after 10 months of therapy.(6)

7. A small study of about 80 people with middle to late-stage non-small cell lung cancer

showed that vitamin B6, along with other treatments, improved the outcome and mitigated some of the damaging effects of the cancer therapies.(7)

8. Hand foot syndrome, an unpleasant swelling of the hands and feet is a side effect of some cancer treatment, has been used in research with vitamin B6 to determine any possible protective benefits. Although the research is mixed, the dosage seems to be the key factor and an ultra-high dose of 400mg (32,000% RDI) was much more effective at treating the syndrome versus dosages of between 50-300mg.(8,9,10,11)

9. In a study of 250 stage 3-4 ovarian cancer patients, 300mg of B6 was effective at reducing the toxicity of the cancer drugs cisplatin and hexamethylmelamine.(12)

10. Marginal vitamin B6 deficiency has been discussed in research as having an adverse effect on cancer risk.(13)

11. In a study following almost 400 participants for 12 months, a high dose of nicotinamide (B3) at 500mg twice daily significantly reduced incidence of non-melanoma skin cancer. The participants had already had this type of cancer, so this study concluded that high dose B3 may serve a protective role in these types of cancers for high-risk patients.(14)

12. A review of the literature determined that folic acid supplementation does not increase colon cancer risk.(15)

Negative Research

1. In a double-blind, placebo-controlled trial of 1470 women from the Women’s Antioxidant and Folic Acid Cardiovascular Study, there was no beneficial impact on colorectal cancer risk despite supplementation with folic acid at 2.5 mg (625% RDI), vitamin B6 at 50 mg (4000% RDI) and vitamin B12 at 1 mg which is about. 18,000% RDI.(16)

2. A group of 379 women, aged at least 42 from the same study referenced above, showed no difference in their risk of developing invasive or breast cancer with combined supplementation compared with placebo.(17)

3. In a 3-year study following over 8,000 patients that had a recent stroke or heart attack, supplementation with folic acid at 2mg, vitamin B6 at 25 mg and vitamin B12 at 500mcg (slightly less than the first study cited in this section) noticed no impact on cancer risk or mortality. Notably, the study also raised a hypothesis based on post hoc analysis (after they saw the data) that folic acid supplementation may increase the risk of cancer in diabetics and reduce the risk of cancer in non-diabetics with a history of stroke or heart attack.(18)

4. A small study of 300 people found no difference in recurrence of certain types of bladder cancer between placebo and those supplementing with B6.(19)

5. A study following patients with heart disease for 5 years found no correlation between supplementing and not supplementing when it came to cancer risk. Notably, the amounts and forms of some of the vitamins in the supplement group were very small compared to other trials showing benefits. They used 3mg of B6 (about 250% RDI), not in the P5P form, and they used 20mcg of B12 (about 100% of the RDI) in the cyanocobalamin form, which is harder for the body to process.(20)

6. A small study of about 100 breast cancer patients looking at the protective role of B6 when administered along with vincristine treatment (a cancer drug) found no difference between the supplemental group (high dose 1500mg B6) and placebo group.(21)

7. A recent study in 2019 looking at over 30,000 people and their serum and genetic data found that higher levels of circulating B12 correlated with an increased risk of lung cancer. For every 150 pmol/L, a standard deviation of 15% increase in cancer risk was observed. Notably, this was significantly higher in men and smokers.(22)

(note: some labs use alternative measurements so make sure they match so you don’t freak out)

8. A large study looking at data from almost 80,000 people aged 50 to 76 and analyzing

supplemental behaviors over 10 years found that B6 and B12 supplementation was

associated with increased lung cancer risk, with the same pattern of preference skewed

toward men and smokers. Interestingly, they found that this significant risk (30-40%

increase) was associated to cases taking the vitamins individually rather than from


9. Some research in elderly populations using a 2-year follow-up found that supplementing with folic acid (at 400mcg per day) and B12 (at 500mcg per day) significantly methylated various genes related to development and growth, potentially raising the risk of cancer and increasing aging mechanisms.(24)

10. A review of the literature concluded that low folate status may inhibit colorectal cancer and that a high folate status may promote it,(25) although other reviews have cited research showing intakes of as high as 5mg per day for 6 years having no impact on colon cancer risk.(26)

11. A review found that chronic consumption of folic acid may lead to high levels of

unmetabolized B9 in the blood and may correlate to cancer or chronic diseases in certain individuals.(27)


Like everything else in health, this shit can be confusing. Some of the research that has

implicated high levels of B vitamins with cancer is very striking, and yet there is no clear mechanism that has been identified as a direct cause for these situations. This is understandable, since the body needs B vitamins for many vital processes, so whatever is actually happening is probably working in the background and involves many other steps.

As always, we have to be careful about drawing conclusions either way as there are many unanswered questions from these studies. I will present you with a few of them below:

1. Because sex hormones have many roles in metabolism and cell growth, it’s hypothesized that this difference accounts for the different types of risk seen in these studies.(28) What this means is that more work needs to be done to see what relationship sex hormones may have in conjunction with certain nutrient intakes on certain specific cancers. This is a very specific topic of study with many permutations, and currently, there really isn’t much research on it.

2. Another issue besides sex is the health status of these individuals. You have cancer growing in your body every day from all of the shit floating around in the environment, but your immune system usually takes care of it. In this sense, it goes back to Germ Theory versus Terrain Theory. Is cancer growth the whole problem, or is a slow and unresponsive immune system due to toxicities, deficiencies and genetics a part of that problem? If so, how much of a part? This is a difficult question to answer, but nonetheless a very pertinent one.

3. Many of these studies did not consider the impact of the form of the vitamin (whether it was methylated or not), nor did they consider the impact of a complete nutrition program. One study referenced above made this conclusion indirectly, finding that those who were taking a multivitamin did not see the increased risk of cancer compared to those just taking B6 and B12 separately.

4. These points are important because everything works together and also because quality counts. Many of the negative folic acid studies brought up the problem of unmetabolized folic acid accumulating in the blood to high levels, but we know that the form of the supplement (along with your genetic tendencies) will drastically influence what it does in your body.

We also know the value of cofactors and how everything is dependent on several other things to synergize; meaning that whenever you act without respecting these relationships, something is bound to get out of balance.

So, what do you think? Are you afraid of getting cancer from taking high doses of B vitamins?

My hope in providing you with all of this information is that you don’t fall for the hype and learn to see through the fear with reason, wisdom and Curiosity for the Truth. It is true that high circulating levels of folate have been associated with cancer, but these levels were very high (30-40 nmol/L and beyond), and indicate both a genetic problem and an over-consumption of unmethylated B9, which are easily corrected with Awareness of the right principles.

Likewise, the serum levels of B12 that were correlated with lung cancer were exceedingly high (over 2 or 3 times the maximum lab value) and were often seen with people who had genetic predisposition to accumulate B12 in their blood. This is why a complete nutrition program along with regular health testing is so important. There are many steps in the complicated chain of breaking down and using vitamins in the body, and if you are missing just one of them (but supplementing something else in excess) it can lead to potential problems.

All that said, if you’re worried about aging from B vitamins, don’t be. Utilize the right tests and your genetics to keep regular tabs on your levels. If you need help in this area, don't be afraid to get in touch.

There is plenty in the supplements I shared at the top of this post (here they are again: Methyl B, Sublingual B12 and P5P) - so start with a conservative dose and base your approach on your micronutrient test and what your genes tell you. If you stop your supplements and get a blood test with a one-day break, notice the serum levels of B6, B12 and B9. If they are exceedingly high (like 30 nmol/L or more for B9 and 2 or more times the high lab value more for B12), cut back because this may be dangerous territory.

It’s unlikely you’ll get there unless you’re overdoing it or using crappy supplements, but keep an eye on everything nonetheless.

Another issue is with excessive alcohol and smoking. It seems that these behaviors amplify whatever is going on in the body with excess B vitamins, and my hypothesis is the following. If you’re doing these things excessively and on a regular basis, chances are you aren’t the healthiest hen in the yard. This means a reduced function in your immune system, increased free radicals and more chances for one of those cancerous mutations to evade the patrol of your immune system and multiply to dangerous levels.

All this, combined with high levels of free flowing B6, B9 and B12 (all of which are food for cells), could be dangerous because it makes it easier for the cancer to get

out of control before your immune system can take care of it.

Conclusion? It’s OK to take high-dose, high-quality B vitamins so long as you test yourself

regularly, know your genes and avoid poisoning your body as much as possible with regular smoking, drugs, alcohol and unmanaged stress. It always comes back to The Basics. After all, you can’t spell them without a “B” in the first place :)

































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Disclaimer & Disclosure:

The information presented on this blog is not intended to treat, diagnose, or cure any disease or ailment. These statements have not been reviewed by the FDA and are not written by a licensed medical professional. Please consult your doctor before using any supplements or beginning any new health regimen, especially if you have any medical conditions. Furthermore, this blog may contain affiliate links to various products. Everything is vetted and tested by me thoroughly before recommendation, but in certain cases I may receive a commission if you purchase through the link. 

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