Folic Acid and Cancer Risk
Does this essential nutrient have a dark side? Understanding the two faces of folate
Monica Reinagel, MS, LD/N, CNS
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Folic Acid and Cancer Risk
Carrie writes:
“A few months ago, I developed an ectopic pregnancy. My doctor told me not to take any more folic acid, a nutrient used by rapidly dividing cells. They wanted to make sure the fertilized egg wouldn’t grow any more. But that got me wondering: If folic acid is used by rapidly dividing cells, such as in an embryo, would it also make you more susceptible to developing cancer? We are still trying to have a baby but now I’m not sure whether it’s safe to resume taking my folic acid supplements. Or am I linking things together in a way that doesn’t make sense?”
Actually, Carrie, you’re thinking very logically—and you’ve zeroed in on a complex and interesting aspect of nutrition. Before I delve into all of that, let me first say that I’m sorry to hear that you’ve had some bumps on the road to starting your family. For those who aren’t familiar with the term, ectopic pregnancy, it refers to a fertilized egg which implants itself somewhere other than in the uterus—usually the fallopian tubes. When this happens, sadly, the pregnancy is doomed. The egg will not survive—and doctors usually need to move quickly to remove the rapidly-dividing cells before they endanger the life of the mother.
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Secondly, although the information I’ll share in this podcast may suggest an answer to your question about whether you should or shouldn’t resume taking your folic acid supplements, I want you to promise to ask your doctor’s opinion on that—because he or she is much better able to advise you based on the particulars of your situation.
And now, let’s take a closer look at the relationship between folic acid, pregnancy, and cancer.
The Good News: Folic Acid Prevents Birth Defects
Women who are planning to get pregnant are strongly advised to take folic acid, which is crucial to the baby’s early development—in particular, to the proper formation of the baby’s spinal cord and brain. In fact, it’s so critical that the government has mandated that certain commonly eaten foods—namely, breads, flours, and other grain-based products—be fortified with folic acid to ensure that all women of child-bearing years are covered, whether or not they are planning to have a baby. This program has been remarkably successful in lowering the rates of certain neurological birth defects, such as spinal bifida.
The Bad News: Folic Acid Could Promote Cancer Growth
Then, a few years ago, a disturbing trend came to light. Looking back, epidemiologists noticed that rates of colon cancer started to rise right about the same time as these fortification programs went into effect. This was surprising: Protection from cancer (including colon cancer) was supposedly among the many benefits of folic acid. Further research revealed a paradox: Although folic acid seems to prevent cancer in healthy people, it can promote the growth of tumors in people with cancerous or pre-cancerous cells.
As Carrie intuited, folic acid’s effect on fast-dividing cells cuts both ways. It is critical for the proper growth of a developing embryo. However, it can also speed the growth of fast-dividing cancer cells. If you were diagnosed with colon cancer, your doctor would probably recommend avoiding supplements containing folic acid—just like Carrie’s obstetrician did when her ectopic pregnancy was discovered. The greater danger, obviously, is for people with pre-cancerous lesions who don’t yet know there is a problem and who are taking high dose vitamins containing lots of folic acid.
Just one more reason that I think that high dose vitamin supplements are a bad idea.
Folic Acid vs. Folate
There’s one more twist in this tale: The words “folate” and “folic acid” are often used interchangeably but there are important differences between them. Folate is the naturally-occurring form of the vitamin. Spinach, lentils, and garbanzo beans are all good sources of dietary folate. Folic acid is the synthetic form of the vitamin that is used in most supplements and in fortified foods. Folic acid and folate work the same in the body, with one exception: The synthetic form (folic acid) is actually better absorbed by the body than the natural form.
Who Should (and Shouldn’t) Take Folic Acid Supplements
If you are pregnant or hoping to become pregnant, your doctor will almost certainly recommend a prenatal supplement containing plenty of folic acid to be absolutely sure that base is covered.
However, people who are at increased risk of colon cancer—either because they are over 50 or because of an inherited predisposition—should take care not to overdo it with the folic acid. I don’t think it’s necessary to avoid fortified grain products—although there are lots of good reasons to be moderate about your grain intake. But I would review any supplements you’re taking and be sure that the total amount of folic acid doesn’t add up to more than 400mcg a day. No matter what, anyone over 50 or with a familial risk should be screened regularly for colon cancer.
In the event that you have a familial history of colon cancer and you’re trying to get pregnant (or in the more unlikely event that you’re over 50 and trying to get pregnant), your obstetrician is the best person to manage those conflicting risks. Finally, I just want to emphasize that there really does not appear to be any risk to anyone from over-consuming natural folate from foods.
Keep in Touch
Thanks to Carrie for suggesting today’s topic. As a thank you, I’ll be sending her a signed copy of my book, Secrets of a Healthy Diet: What to Eat, What to Avoid, and What to Stop Worrying About, available wherever you buy or download books. If you have a suggestion for a future show topic or would like to find out about having me speak at your conference or event, send an email to nutrition@quickanddirtytips.comcreate new email.
You can also post comments and questions on my Nutrition Diva Facebook Page. I answer a lot of listener questions in my free weekly newsletter, so if you’ve sent a question my way, be sure you’re signed up to receive that.
Have a great week and remember to eat something good for me!
About the Author
Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes’ most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation’s leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.