Chapter One

DHA ~ Your New Best Friend

So, what exactly is DHA?

A. Actually, DHA is its nickname. Its full name is docosa-hexaenoic acid. (Now you know why we like using its nickname!)

DHA is a particular kind of fatty acid. You can think of a fatty acid as being a building block of fat. Imagine a key-ring with three keys on it. You can think of the individual keys as fatty acids, and the combination of the three connected by a key-ring to be a unit of fat. Just as keys come in many different lengths, sizes, and styles, fatty acids can too. So, DHA is simply a specific kind of "key" on the key ring.

Q. Is DHA related to DHEA?

A. NO! Not at all. DHEA stands for di-hydroxy-epi-androsterone, and it is a steroid hormone. On the other hand, DHA is a fatty acid. Besides sharing three common letters, DHA has nothing to do with DHEA.

Q. What makes DHA different from other fatty acids?

A. DHA is indeed unique. It has twenty-two carbon atoms and six double bonds, making it the most unsaturated fatty acid available in the diet. It is also an omega-3 fatty acid, which just means that its first double bond occurs after the third carbon atom.

The technical descriptions are important only for a detailed, biochemical understanding of how DHA works. We need only appreciate that its numerous atoms and double bonds allow it to twist and turn in ways no other fatty acid can. These features make it uniquely suitable for special roles in cells that no other fatty acid can play. For instance, its presence in the brain, synapses, eyes, and mitochondria are vital to their healthy functioning.

Q. What special role does DHA play in the brain ?

A. Your brain is actually made up of more than 60% fatty substances. It is a collection of billions of intricately woven cells. One kind of cell is the nerve cell, called a neuron, and it is responsible for communicating electrical signals throughout the brain and rest of the body. A protective membrane called a lipid bilayer surrounds each neuron. The lipid bilayer consists of two layers of compounds called phospholipids. Each phospholipid has a saturated fatty acid and an unsaturated one. You guessed it: the unsaturated one is usually DHA.

Q. What are synapses and how is DHA related to them?

Synapses are where individual neurons connect with other neurons, where they talk to each other, transmitting and receiving chemical signals, called neural transmitters. Colloquially, when we say nerves are firing, we are actually referring to the chemical information exchange occurring at the synapses. Each neuron can have thousands, even tens of thousands of synaptic connections with other neurons. In fact, every new experience, memory, or skill we have results in the formation of new connections. Some researchers suggest that the more synaptic connections you have, the better your mind is able to function.

Interestingly, DHA is more concentrated in the membranes at the synapses than any other place in the body. Its unique shape and size is needed for neurons to successfully exchange neurotransmitters. If the brain does not have enough DHA to meet the need, it will use in its place an omega-6 fatty acid, DPA. However, DPA does not nearly fit as nicely as DHA, and the communication between neurons at the synapses may therefore suffer.

Q. What special role does DHA play in the eye?

A. The retina is the light-sensitive part of the eye. It is a layer of many different kinds of cells. Just like neurons, these cells are protected by a lipid bilayer, which in turn consist of phospholipids. This time, both fatty acids of the phospholipid are unsaturated, and typically, both are DHA. You can imagine the importance of getting enough DHA during the first few years of life, when the brain, eyes, and nervous systems are developing. Even into adulthood, the body needs adequate amounts of DHA to maintain and replace cells.

Q. Why is DHA in the mitochondria?

A. The mitochondria is the powerhouse of the cell. It is where the chemical energy ATP is produced, which can then be used by cells to power all its reactions. We normally associate burning calories with strenuous physical exercise, like running or swimming. Here, our muscles are using large amounts of ATP to contract and cause motion. But the brain also requires a huge amount of ATP energy to function. Feel the top of your head right now. It's warm. That's a sign of calories burning! And when it gets cold outside, you wear a hat to help keep that warmth from convecting away

Fatty acids such as DHA are used by the mitochondria as a source of fuel to produce ATP. Normally, the simple sugar glucose is used. But an alternative source is a fatty acid like DHA. The mitochondria takes two carbon atoms at a time in a process called beta-oxidation, like chopping up a carrot into thin slices. It takes each of the slices and uses it to form ATP energy. Because DHA has twenty-two carbon atoms, it is an excellent source of stored energy, which the brain may utilize for its great energy requirement.

Q. How else does the body use DHA?

A. The body also uses fatty acids as the starting materials for special chemicals called prostaglandins, which in turn play specific health roles. There are many different kinds of prostaglandins, and they can be categorized into three families or series, labeled PG1, PG2, and PG3. Specifically, DHA promotes the PG3 series, and its health benefits include inhibiting blood clotting, reducing LDL cholesterol and triglycerides, lowering blood pressure, alleviating inflammation, and diminishing brain vessel spasms.

Q. Is DHA an essential nutrient?

A. An essential nutrient, like Vitamin C, is something the body cannot make and needs to obtain from the diet. DHA is considered a non-essential nutrient, because the body is able to manufacture it from another fatty acid, EPA (eicosa-pentaenoic acid). However, the enzymes which convert EPA into DHA are often very slow and inefficient. Thus, it makes sense to get DHA directly from the diet.

The only essential omega-3 fatty acid for humans is ALA (alpha-linolenic acid). The body cannot manufacture ALA, but obtains it from the diet. In principle, ALA can be converted into EPA by special enzymes. Then EPA, as mentioned, is further converted into DHA. However, many factors may hinder this enzymatic conversion process. Generally, relying on ALA's conversion to DHA is not the surest way of ensuring your body gets enough DHA.

Q. What is the difference between an Omega-3 Fatty Acid and DHA?

A. DHA is one particular kind of omega-3 fatty acid. The omega-3 fatty acids are a group of fatty acids which share a common trait, specifically, that the first double bond occurs after the 3rd carbon atom. Many fatty acids have this trait, such as DHA, EPA, and ALA. The difference between these fatty acids is the total number of carbon and hydrogen atoms each has. DHA has twenty-two carbon atoms, EPA has twenty, while ALA has eighteen. Each plays unique roles in the body, depending on their different structures. Yet they are all classified as omega-3 fatty acids and share the defining trait.

Q. What about Omega-6 Fatty Acids?

A. As the title suggests, omega-6 fatty acids are a group of fatty acids characterized by having the first double bond after the sixth carbon (and not the third, as in the case of an omega-3 fatty acid.) Examples of omega-6 fatty acids are linoleic acid, gamma-linolenic acid, and arachidonic acid.

The names are not too important to us. What is important is realizing that for optimal health, the diet should contain almost the same amount of omega-3 fatty acids as omega-6 fatty acids. The typical western diet is rich in foods (such as beef, eggs, milk, and corn oil) providing plenty of the latter, but little of the former. This might be part of the reason why supplementing with omega-3 fatty acids such as DHA seems to improve certain health conditions. Balance is an important key.

We can understand how this balance is achieved by recalling that the body uses fatty acids to form prostaglandins. For instance, the body uses arachidonic acid, an omega-6 fatty acid, to form prostaglandins in the PG2 series. One member in this series, PGE2 affects the body in many ways just opposite to PG-3, which we considered above. Namely, PGE2 accelerates blood clotting, increases LDL cholesterol and triglycerides, raises blood pressure, promotes inflammation, intensifies spasms in brain vessels, worsening migraines. These functions are not necessarily bad, because in certain situations, the body needs exactly these things. For instance, if you cut yourself, you surely want your blood to clot quickly, or else you will bleed to death. The problem arises when we eat so much arachidonic acid that the body is filled with substances like PGE2. Then, it is out of balance, and blood clotting begins where it is not suppose to, such as inside blood vessels.

Q. What foods are good sources of DHA?

A. Cold water, fatty fish such as cod, salmon, mackerel, sardines, trout and albacore tuna are excellent sources of both DHA and EPA. Fish oils, such as cod liver oil, are also rich in these omega-3 fatty acids. Chicken meat and chicken eggs can be good sources, too, since many chickens are raised on feed consisting of fish.

Many people find the pungent odor of rotting fish to be very unpleasant. In fact, this characteristic "fishy" smell comes from rancid DHA. Recall that DHA is very unsaturated, so it is very susceptible to free radical damage. Such molecular damage is the microscopic reason why fish spoils, resulting in the pungent fishy stench. That is also why you should be very careful in eating only the freshest fish possible. Even the heat of cooking fish will destroy much of this delicate fatty acid. If that bottle of cod liver oil smells too fishy, throw it out and buy a new one. Fresh fish oil has almost no odor whatsoever, and only a slight after-taste.

Q. Are DHA supplements available?

A. Yes, many supplement manufacturers provide a wide variety of DHA products. Most use fish oil or algae as natural sources. Because of its delicate nature, careful processing and handling of DHA is extremely important. Thus, choose only respected brands with solid reputations for consistently high standards of quality control and testing. We will look closely in a latter chapter on how best to supplement with DHA.

Q. Are DHA supplements advisable?

A. What to supplement is a personal issue based on an individual's unique biochemistry and health conditions. Unarguably, the typical western diet is poor in sources of DHA. Moreover, certain people may have much greater needs for DHA, as we will discover. These include infants, pregnant and lactating women, and the elderly. Those suffering from depression, addictions, inflammatory diseases, vision problems, and heart ailments may also benefit from increasing their DHA intake. So, DHA supplementation may play an important role in both maintaining and improving health.

Now that we have properly met our new friend and learned about some of its roles in the body, we are ready to appreciate why medical and nutritional scientists are so excited about how it can help in a variety of situations. We are only at the beginning of this great discovery, and many more studies are in the works. That's what is so appealing about science: itĚs like a never-ending train ride through spectacular scenery. I invite you to appreciate the view, and stick around for the rest of the ride.