Egg yolks are probably the best source, containing an average of 125 milligrams per yolk.
Back in the mid-’60s and early ’70s, bodybuilders didn’t have the
huge variety of supplements that are now available—like “fat burners.”
While numerous supplements now tout their ability to help you burn up
excess bodyfat, bodybuilders of yesteryear turned to lipotropics for
that purpose. Lipotropic literally means “fat loving.” From a
medical perspective, a lipotropic was something that helped to clear fat
out of the liver. In fact, one of the earliest signs of liver failure
is an excessively large fat content in the organ. The liver uses
lipotropics to help clear out excess fat. So, when you’re deficient in
them, you can accumulate excess fat in your liver.
Most nutritional lipotropics work by donating a methyl group, which
is the base for the production of many vital body substances, such as
creatine. The primary nutrient lipotropics are lecithin and
phosphatidylcholine, choline and betaine, which is produced from
choline. Choline and inositol were sold as “lipotropic supplements” 40
years ago, and bodybuilders referred to them as “fat burners.” While
they were not actually directly involved in fat oxidation, they played
important roles in the liver synthesis of lipoproteins, which helped to
transport fatlike substances in the blood. A lack of choline and other
methyl donors led to a drop in the production of lipoproteins, causing a
backup of fat in the liver. So you can see how the thinking went:
Because choline helped the liver rid itself of excess fat deposits,
using choline would do the same for excessive fat elsewhere in the body.
Besides helping the liver control fat storage, choline plays a number
of other important roles in the body. Choline and other methyl donors,
such as S-adenyl methionine, a.k.a. SAMi, help the body to break down
homocysteine, a by-product of the metabolism of the essential amino acid
methionine. Homocysteine is toxic in large quantities, however, and is
linked to cardiovascular problems and other diseases.
Choline and lecithin also are vital for the maintenance of cellular
membranes—a lack of choline leads to cellular death. Choline plays
important roles in brain health as well, not only in relation to
cellular membrane repair and production but also because it’s the
precursor of acetylcholine, a brain neurotransmitter. Acetylcholine is
low in someone who has a degenerative brain disease, such as
Alzheimer’s. In fact, Alzheimer’s disease seems to target neurons that
produce acetylcholine. The lack of acetylcholine is responsible for the
typical memory and learning problems of those who have degenerative
brain diseases.
In addition, acetylcholine is the primary neurotransmitter at the motor neuron, meaning that it’s required to transmit messages from the central nervous system to your muscles, enabling them to contract. Some
studies show that exhaustive exercise can deplete the body’s choline,
leading to deficits in muscular function. More recently, several studies
have shown that betaine, which is a by-product of choline metabolism,
helps to maintain exercise intensity. Betaine is also efficient at
helping to convert excess homocysteine back into methionine.
Until 1998 choline wasn’t officially considered an essential
nutrient, but based on a review of ongoing research, the Institute of
Medicine recognized it as being essential in human nutrition that year.
The reason choline was overlooked for so many years was that scientists
believed that it could be synthesized in the body in sufficient amounts
from SAMi, but that turned out to be highly inefficient, most likely
because of the many other functions related to SAMi. One study of
healthy adults deprived of choline found that 77 percent of men and 80
percent of women developed clear signs of choline deficiency, including
fatty liver and muscle damage. Another 10 percent still showed
deficiency symptoms even when they got the recommended daily intake,
which indicates that the requirement for choline may differ widely due
to genetic factors. The current suggested intake for adults aged 19 and
over is 425 milligrams a day for women and 550 milligrams for men.
Most choline that we take in is converted in the body into lecithin,
which, in turn, is the predominant phospholipid in cell membranes. It
makes up more than 50 percent of the content of such membranes, which
also contain cholesterol.
More recent studies show that subjects who got the most
choline and betaine also had the lowest levels of several inflammatory
markers. That’s important because out-of-control inflammation
is now known to be the underlying cause of most degenerative diseases,
including cardiovascular disease, cancer and brain disease. Inflammation
tends to increase with age, and choline and other methyl donors may
help to offset the effects of what’s been called “inflamaging.”
Cancer is linked to cellular mutations caused by damage to DNA, which
is needed for orderly cell replication. Full DNA repair processes
require sufficient methyl donors—the implication being that without
sufficient methyl donors such as choline available, the risk of cancer
increases. Indeed, several preliminary studies suggest that a high
choline intake is associated with lower rates of breast cancer.
Rich food sources of choline include liver, eggs and wheat germ. Egg yolks are probably the best source, containing an average of 125 milligrams per yolk.
Yet the practice of discarding egg yolks in favor of eating only egg
whites continues to be popular among bodybuilders. The thought is that
the yolk contains all the fat and cholesterol found, while the white is
nearly pure protein. The problem with that theory: Besides containing
choline, the yolk also contains all the other nutrients found in
eggs—including half the protein. Studies show that the fat
contained in eggs has no harmful effects on human health, and even the
cholesterol content is overplayed. For most people, eating whole eggs doesn’t adversely affect blood cholesterol. In fact, cholesterol
is actually good for building muscle, as it’s not only a constituent of
cell membranes but also the precursor of testosterone synthesis in the
body.
As with other nutrients, it is possible to get too much choline.
Doses of 7.5 grams have produced nausea, diarrhea and a drop in blood
pressure in some people. Doses of up to three grams a day are considered
safe. Some people lack an enzyme that causes the buildup of a choline
metabolite called trimethylamine in the body. More specifically, gut
bacteria convert choline into trimethylamine, then the enzyme (which is
lacking in about 1 percent of the population) converts trimethylamine
into trimethylamine-N-oxide. Without the enzyme, trimethylamine builds
up in the body and is excreted in urine, sweat and breath; however, the
increased amounts cause a disgusting odor akin to rotting fish. Having
certain types of viral hepatitis can also lead to the buildup of
trimethylamine in the body. Cases are on record of marriages ending
because one spouse smelled like rotten fish, which was traced to the
buildup of trimethylamine from normal choline intake.
More recently, a far more serious effect related to trimethylamine has been reported.1
Researchers found that depending on the content of intestinal bacteria,
or flora, some people produce excessive amounts of
trimethylamine-N-oxide from lecithin and choline. When fed to mice,
lecithin and choline promoted an increase in foam cells, which are cells
laden with fat and cholesterol. An increase in such cells is considered
the first stage in the development of atherosclerosis, the buildup of
plaque in arteries that leads to cardiovascular disease. Betaine was
also found to be involved in the process. Based on those preliminary
findings, the authors question the wisdom of taking supplemental
betaine, choline or lecithin. They note that “excessive” amounts of
those nutrients could lead to cardiovascular disease though the activity
of gut bacteria.
That raises a number of questions. How do we know who has the precise
balance of gut bacteria that would produce the negative effect? Also,
since many people, including bodybuilders, avoid eating egg yolks, the
primary food source of lecithin and choline, what will happen if they
don’t use choline or lecithin supplements? As noted above, one such
effect could be fatty liver.
While the main cause of fatty liver used to be excessive alcohol
intake, more recently cases in which alcohol wasn’t a factor have shown
up. That type of fatty liver is linked to insulin resistance and the
metabolic syndrome, itself a precursor of cardiovascular disease and
diabetes. Since choline is needed to clear the liver of
excessive fat, not getting it in some form would make a bad situation
even worse. Taking a special type of probiotic supplement could restore
the balance of intestinal bacteria, preventing the cardiovascular side
effects of taking choline or lecithin.
Perhaps the most prudent thing you can do in the meantime is to stop
discarding egg yolks. They won’t blunt any fat-loss efforts, but they
may help protect your long-term health.
—Jerry Brainum
1 Wang, Z., et al. (2011). Gut flora metabolism of phosphatidycholine promotes cardiovascular disease. Nature. 472.
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