Recent dietary surveys suggest that most of us are only getting 65 to 75% of the Adequate Intake. But Adequate Intake may be higher than the actual needs for many groups. Who is and isn't getting enough?
Let’s talk about choline: an important nutrient that you may never have heard of.
What is choline?
Choline is sometimes lumped together with the B vitamins, and while it is not technically a B vitamin, it does share some characteristics common to that family of nutrients. We humans have the ability to manufacture choline in our livers (which is called de novo synthesis, or synthesis "from new"). But we can’t make enough of it to meet our needs and so it is considered an essential nutrient—meaning we must get it from our diets.
What does choline do for us?
Choline is required to make a lot of biologically important molecules, including phosphatidylcholine and the neurotransmitter acetylcholine. It’s critical to brain and nervous system function and plays a very important role in early brain development, both in the womb and in early life.
In fact, new research on the role of choline in fetal brain development has prompted the American Medical Association to push for a higher level of choline in prenatal vitamins. Up until recently, many prenatal formulations didn’t even include choline or included it only in very small amounts.
The AMA would like to see 450 mg of choline in prenatal formulations. One challenge is that choline is a sort of bulky nutrient and including higher amounts in a prenatal would make the tablets a lot bigger. It might be more feasible to recommend that pregnant women take a choline supplement in addition to their prenatal. For now, it’s up to women and their doctors to make sure that this need is being met.
Choline has a lot of other important functions in the body, including protecting the liver. A deficiency of this nutrient can lead to a buildup of fat in the liver, which can eventually lead to liver damage or even cancer.
See also: What is non-alcoholic fatty liver disease?
Where do we get choline?
The richest dietary sources of choline are eggs, organ meats (like liver), fish and shellfish, beef, pork, and chicken. Of the plant-based sources, Brussels sprouts, broccoli, and other cruciferous vegetables are your best bets.
How much choline is enough?
Good question! Choline does not have a recommended daily allowance (RDA) because the panel of experts that establishes those recommendations feels that there is not enough data to determine what amount is sufficient. When there’s not enough information to set an RDA, the National Academy of Medicine punts by setting an Adequate Intake (AI) instead. This is based on the amount that healthy people seem to be eating—with the assumption that if they’re generally healthy, they must be getting enough.
The AI for choline is 550 mg/day for adult men and 425 for adult women; a bit more if you’re pregnant or breastfeeding. And that is based primarily on a single study involving only men, which found that men getting less than that amount were at risk of developing fatty liver.
The amounts for women, children, and teens were extrapolated from that, based mostly on relative body size. But, of course, women and children are not simply smaller men. There are a lot of important hormonal and metabolic differences between these groups that may affect their needs.
As choline researcher Marie Caudill, from Cornell University, explained to me, estrogen upregulates de novo choline synthesis in the liver. So premenopausal women may need less dietary choline than men do in order to prevent deficiency.
On the other hand, due to the role choline plays in tissue expansion and fetal brain development, pregnant women may need much more. And in fact, some of Caudill’s research has shown benefits for women taking twice the AI recommendation during pregnancy.
Given its importance, I’m eager for researchers to produce enough evidence to allow us to set actual RDAs for choline in the different life stages. Hopefully, we are getting closer to that threshold. But in the meantime, we’re stuck with this AI.
We also have a UL (or upper limit) for choline. The recommended maximum intake is 3500 mg a day, which is half of the amount that has been shown to cause symptoms of toxicity. It would be pretty tough to come close to this through diet alone. You’d have to eat two dozen eggs or 35 servings of meat a day to get there. Virtually the only way to overdo it with choline is through supplementation—and choline is not a very widely used dietary supplement.
How much choline do people typically get from their diets?
Recent dietary surveys suggest that most of us are only getting 65 to 75% of the Adequate Intake. But remember that the Adequate Intake may be higher than the actual needs for many groups. And there doesn’t appear to be evidence of widespread choline deficiency in healthy people.
Are vegetarians at increased risk?
Maybe not, says Dr. Caudill. Those who do not eat eggs or meat are most likely getting a lot less choline than those who do. On the other hand, she says, they may be getting more betaine, a closely related nutrient found primarily in plants. Our bodies can make betaine from choline. But if we’re getting a lot of betaine from our diets, that might spare some of the choline we take in for other uses. Those with higher betaine intakes could theoretically need less choline. Again, more research is needed.
Is there a link between choline and prostate cancer?
A Nutrition Diva listener recently asked me to look into this after coming across some research showing that choline seemed to increase the risk of prostate cancer.
It’s actually a little more complicated than that. A couple of observational studies in men with prostate cancer found that those who got more choline from their diets had a higher risk of dying of their disease. On the other hand, large population studies find an inverse relationship between choline intake and cancer, meaning that those who got more choline had a lower risk.
Dr. Caudill doesn’t find this so surprising. Choline is very important for cell division, she explains. This is one of the reasons it’s so important during pregnancy, when there is a very high rate of cell division. Cancer is also characterized by a high rate of cell division, but in this case, it’s pathological. It makes sense that a nutrient that fuels healthy cell division in healthy people could also support unhealthy cell division in someone with cancer.
We’ve seen similar situations with folic acid. For the general population, folic acid appears to be protective against colon cancer. For those with colon cancer, a high intake of folic acid might promote the growth of the cancer.
See also: Folic Acid and cancer risk
Clearly, nutrition recommendations always need to be tailored to the situation. Anyone with cancer should definitely consult with their oncologist or, better yet, an oncological nutritionist about their diet and any supplements they take.
Is there a link between choline and heart disease?
The link between choline and heart disease is similarly complex. High levels of an inflammatory molecule called homocysteine have been linked to an increased risk of heart disease. One of choline’s many functions is as a methyl donor, which recycles homocysteine into the less reactive molecule methionine. So, it’s logical to think that choline would help protect the heart and reduce the risk of heart disease.
On the other hand, choline intake can increase blood levels of TMAO, a metabolite that has been identified as a possible risk factor for heart disease. But TMAO production is not only affected by diet. It's also influenced by our gut microbes and is, in part, genetically determined.
And then there's this: fish consumption, which has long been recognized for its heart-protective properties, raises blood TMAO to a far greater extent than eggs, beef, or other high choline foods. So, it’s really unclear whether higher TMAO levels as a result of choline consumption (as opposed to other causes) are a factor in heart disease.
For what it’s worth, large population studies have found no correlation between choline consumption and risk of heart disease.
Do you need a choline supplement?
I’m always in favor of getting our nutrients from foods rather than supplements—especially when this motivates us to prioritize whole foods in our diets. Those who include eggs and/or meat in their diets are probably getting enough choline to meet their needs.
Those looking for plant-based sources of choline should be sure to include broccoli, Brussels sprouts, and other cruciferous vegetables on a regular basis.
But people in certain categories—such as pregnant and breast-feeding women—may need more. Be sure to discuss the merits of choline supplementation with your doctor.