Choline Is an Essential Nutrient
Are You Getting
Study shows that current Adequate Intake values
for men and women may be inadequate
By Will Block
icture the following classic cartoon. The scene is a classroom filled with middle-aged adults who are enrolled in an adult education class, Economics 101. It is apparently the first day of class. As the initial lesson, the professor has just written on the blackboard, “Don’t spend more than you take in.” A heavyset guy with a somewhat porcine look raises his hand and says, “I don’t get it.” The cartoon’s caption reads, “Can You Spot the Congressman?”
Should we laugh or cry? It’s hard to say, when something so absurd is also so true.
The Feds’ Lowball Criterion: Disease Prevention
Here’s something similarly absurd: the federal government’s recommendations for our daily intake of a variety of nutrients (mainly vitamins and minerals) have traditionally been designed merely to prevent the occurrence of deficiency diseases, not to maintain good, let alone optimal, health. That’s like feeding your dog just enough that he doesn’t bite your hand out of hunger, but not so much that he’d lick it out of love. You could do much better than that for your dog—and the government could do much better for you.
But to be fair, the task in question is challenging, even in terms of establishing the minimal levels required for disease prevention. Beyond that lowball criterion, the task becomes much more difficult and contentious when the experts try to define the requirements for the ideal state of optimal nutritional health. After all, individuals vary greatly in their nutritional requirements, owing to many factors, such as heredity, gender, age, lifestyle choices, available foods, and general state of health. In the case of vitamin D, even geographic location is important (see
“Vitamin D and Calcium Combat Cancer” on page 23 of this issue).
All About Choline
So perhaps we should be sympathetic and cut the feds some slack . . . nah. (For more on this frustrating subject, see the sidebar.) Ironically, it may be that the feds didn’t do too bad a job, with the data they had, in recommending preliminary Adequate Intake (AI) values for an essential nutrient that is neither vitamin nor mineral. It’s choline, a nitrogenous alcohol obtained mainly—but not always sufficiently—from milk, eggs, liver, and peanuts.
Pauling Blasts the Feds
Among the best books ever written for laymen on human health and nutrition was How to Live Longer and Feel Better by Linus Pauling. Written in his characteristically muscular style, and reflecting his peerless scientific authority, the book presents clearly stated views on a wide variety of health and nutrition issues that face us all as we grow older.
Although it’s now out-of-date in some respects, the book still resonates with the wisdom of a great scientist who was dedicated to bettering the human condition and who was unafraid of making enemies in high places, whether it was the medical establishment, the pharmaceutical industry, or government agencies that he thought were too hidebound in their thinking.
The book gave Pauling a platform from which to air his opinions of the federal government’s record in providing nutritional information to the public. Let’s just say that these opinions did not make the government happy. Following are two passages from the book that give a flavor of what he thought of the feds.
From page 4:
It is far easier to obtain reliable information about the factors determining the health of guinea pigs or monkeys than of human beings, and I have relied to some extent on the studies made on these and other animal species.
I am, for example, impressed by the fact that the Committee on the Feeding of Laboratory Animals of the U.S. National Academy of Sciences–National Research Council recommends far more vitamin C for monkeys than the Food and Nutrition Board of the same U.S. National Academy of Sciences–National Research Council recommends for human beings. I am sure that the first committee has worked hard to find the optimum intake for the monkeys, the amount that puts them in the best of health. The second committee has not made any effort to find the optimum intake of vitamin C or of any other vitamin for the American people. In its Recommended Daily Allowances, so well publicized that they are referred to on breakfast-cereal boxes by the initials RDA, the committee rations the vitamins at not much above the minimum daily intake required to prevent the particular deficiency disease that is associated with each of them.
No evidence compels the conclusion that the minimum required intake of any vitamin comes close to the optimum intake that sustains good health.
From page 18:
The discovery of vitamins during the first third of the twentieth century and the recognition that they are essential elements of a healthy diet was one of the most important contributions to health ever made. Of equal importance was the recognition, about twenty years ago, that the optimum intakes of several of the vitamins, far larger than the usually recommended intakes, lead to further improvement in health, greater protection against many diseases, and enhanced effectiveness in the therapy of diseases. . . .
As early as 1937, Albert Szent-Györgyi, the scientist who isolated vitamin C, had said that vitamins, used in the proper way, could have fantastic results in improving human health. Yet even now, a half century later, the old-fashioned nutritionists, speaking with the authority of the Food and Nutrition Board of the U.S. National Academy of Sciences–National Research Council, continue to ignore the evidence about the value of the optimum intakes of these important substances. They persist in recommending no more than the minimum supplementary intakes, established by clinical experience a half century and more ago, necessary to prevent the diseases associated with deficiency of the vitamins in the diet. Their recommendations stand in the way of wider popular understanding and practice of the new nutrition.
Since Pauling wrote those words 21 years ago, the situation has improved only a little. The most positive step has been the gradual shift, during the past decade, of the responsibility for nutritional recommendations from the FDA to the nonprofit, nongovernmental Institute of Medicine, one the four United States National Academies. That may bode well—time will tell.
- Pauling L. How to Live Longer and Feel Better. W. H. Freeman, New York, 1986.
Choline’s principal role in human physiology is as a precursor to several other important compounds:
- Phosphatidylcholine and sphingomyelin – These two phospholipids are important structural components of our cell walls. They also act as sources of certain compounds involved in cell-signaling functions, as do some other metabolites of choline. (Phosphatidylcholine is also known as lecithin.)
- Acetylcholine – This vital neurotransmitter activates all of our muscles. It’s also the principal facilitator of neuronal signals in those regions of the brain that are involved in learning, memory, and other cognitive functions (the cholinergic system). When acetylcholine is depleted in Alzheimer’s disease, the brain may “autocannibalize” its own neurons by taking choline from the phosphatidylcholine molecules in the cell walls. This helps alleviate one problem at the expense of another: degradation of the cell walls, which hastens the process of neuronal loss seen in Alzheimer’s patients. Thus it’s especially important to maintain adequate choline levels when cholinergic function may be impaired. (See
“A Tale of Two Cholines,” May 2005.)
- Betaine – This oxidation product of choline is an important molecular donor of methyl groups (–CH3), which are involved in many important physiological processes, including the conversion of the harmful amino acid homocysteine to harmless methionine. (See
“Choline Battles Homocysteine,” April 2005.)
Choline Deficiency Leads to Liver Dysfunction
In 1998, the Food and Nutrition Board (FNB) of the Institute of Medicine declared choline to be an essential nutrient, because it must be consumed in the diet in order to meet our metabolic needs and maintain good health. Choline is not considered a vitamin, however, because our bodies can produce small amounts of it via the enzymatic breakdown of phosphatidylcholine. In establishing daily AI values for choline, the FNB’s main criterion was the prevention of liver dysfunction, the primary consequence of choline deficiency.
In 2003, the Linus Pauling Institute (LPI) endorsed the FNB’s recommendations in the context of the following statement:
Little is known regarding the amount of dietary choline required to promote optimum health or prevent chronic disease in humans. The Linus Pauling Institute supports the recommendation by the Food and Nutrition Board of 550 milligrams (mg)/day for adult men and 425 mg/day for adult women. . . . Little is known regarding the amount of dietary choline most likely to promote optimum health or prevent chronic disease in older adults. At present, there is no evidence to support a different intake of choline from that of younger adults . . .
The LPI report was peer-reviewed by Dr. Steven H. Zeisel, a professor of nutrition at the University of North Carolina at Chapel Hill. Dr. Zeisel, a leading authority on choline, serves on the Institute of Medicine’s Panel on Folate, Other B Vitamins, and Choline, which is responsible for recommending the AI values for these nutrients. He has published many research papers on choline, the latest of which changes the picture painted above.
The First Choline Study to Include Women
The new paper illustrates how difficult is the task that we’ve been discussing. Its title gives a hint: “Sex and menopausal status influence human dietary requirements for the nutrient choline.” (Zeisel was the research team’s leader, but he’s listed last among the authors, which is not uncommon.) Amazingly, this was the first study of choline requirements that included women, according to the authors; this must mean that the existing AI value for women was established on theoretical grounds only.
The initial objective of the study was to evaluate the dietary requirements for choline in 57 healthy men and women (aged 18–70) and to investigate the consequences of choline deficiency. The ultimate objective was to refine the information on which the Institute of Medicine’s Food and Nutrition Board based its preliminary Adequate Intake values and, perhaps, to enable the calculation of a more relevant Estimated Average Requirement for choline, on which the Dietary Reference Intake (DRI, the final word) would be based.
Women’s Menopausal Status Makes a Big Difference
The details of how this study was conducted are mind-numbing, so let’s just cut to the chase. The researchers found, first of all, that 77% of men and 80% of postmenopausal women in their study developed subclinical liver or muscle dysfunction (causing no harm) when they were fed a choline-deficient diet [less than 50 mg per 70 kg (154 lb) of body weight per day] for 6 weeks. Remarkably, the rest seem to have done all right on this diet.
This organ dysfunction occurred, however, in only 44% of premenopausal women on the choline-deficient diet, perhaps because of their high levels of estrogen, which facilitates the synthesis of phosphatidylcholine. Since the body can obtain choline from phosphatidylcholine, having higher levels of the latter would reduce the need for choline from food or supplements.
The Old “Adequate Intake” May Be Too Low
The researchers also found that the current AI of 550 mg for men may be inadequate for some men, because 23% of the men in their study became choline-deficient (as evidenced by organ dysfunction) at that level of intake per 70 kg of body weight per day. The deficiencies were reversed when the men’s choline intake was increased to 825 mg per 70 kg of body weight per day.
Overall, 550 mg per 70 kg of body weight per day for men was sufficient to prevent or reverse organ dysfunction (disease prevention!) for 81% of the subjects in this study; the remaining 19% needed 825 mg per 70 kg of body weight per day, or the amount of choline in an ad libitum (no limitations) diet containing more than 550 mg per 70 kg of body weight per day. In the authors’ words, “This data should help inform the Institute of Medicine as they refine estimates for DRIs for choline.” Let’s hope so.
What About Optimal Health?
The question is, will the Institute of Medicine ever get beyond mere disease prevention and set its sights higher, on optimal health? Again, let’s hope so, but the new data discussed above are still in the disease-prevention realm.
Meanwhile, there is reason to believe that substantially higher amounts of choline—perhaps 2 to 3 g/day—may be essential for optimal health, especially in the elderly. Compared with younger people, the elderly show a greatly reduced bioavailability of choline to the brain after ingesting a single, substantial dose of it. A higher daily intake might compensate for that effect and could conceivably offer protection against neurodegenerative diseases such as Alzheimer’s.
- Higdon J. Choline. Linus Pauling Institute, Corvallis, OR, 2003.
- Fischer LM, daCosta KA, Kwock L, Stewart PW, Lu TS, Stabler SP, Allen RH, Zeisel SH. Sex and menopausal status influence human dietary requirements for the nutrient choline. Am J Clin Nutr 2007;85:1275-85.
- Cohen BM, Renshaw PF, Stoll AL, Wurtman RJ, Yurgelun-Todd D, Babb SM. Decreased brain choline uptake in older adults. JAMA 1995;274(11):
Will Block is the publisher and editorial director of Life Enhancement magazine.