DHA Supplementation

When we think of aging, we think of the obvious—wrinkles and achy joints, for example. We usually don’t consider things such as worsening vision or memory loss until we are well on our way to senior status. But we should. After all, the disorders that may go along with the aging of the nervous system are some of the most frightening problems we face—dementia, Alzheimer’s disease, and macular degeneration, for example. However, there is a way to fight this “neuro aging.” Use dietary supplements.

DHA

DHA (docosahexaenoic acid) is an essential fatty acid (EFA). EFAs are called “essential” because very little can be synthesized by the body—we must obtain them from our diet. DHA is one of the omega-3 fatty acids, whose best-known source is perhaps fish oil.

EFAs are necessary for good health, and DHA is well-known as one of the keys to a healthy nervous system. DHA is the building block of human brain tissue—60 percent of the brain is fat, and DHA is the most abundant fat in the brain, as well as in the retina of the eye. DHA is essential in communication between the brain and nervous system—it plays a role in the cell membrane, where the electrical impulses that are the basis of communication within the nervous system are generated. Without DHA and other fatty acids, communication within this system can break down or become less effective.

The importance of DHA to the brain and nervous system is seen early in our development. In the first few weeks of embryonic development, the mother’s blood supplies the fetus with large amounts of DHA. In the last trimester of a pregnancy, the DHA content of the brain’s cerebrum and cerebellum—which contains centers for speech and abstract thought—increases threefold.

DHA is recognized as extremely important—so much so that the World Health Organization has recommended that DHA be added to infant formulas. Many health practitioners also recommend it for pregnant women and nursing mothers.

DHA supplementation may be especially important as we grow older. The body’s ability to synthesize DHA, which is limited in all people, may decline even further with age. This is compounded by the small amounts of DHA we get in our diet, especially those who strive for a vegetarian diet—the richest sources of DHA are red meats, animal organs, and eggs.

Research indicates that low levels of DHA may be involved in a number of health problems relating to the nervous system.

Depression

Depression is on the rise in North America. This is often attributed to the ups and downs of our lives and is often seen among the aging population. However, recent research indicates that there may be a physiological aspect to depression that relates to nutrition.

A study published in the American Journal of Clinical Nutrition (62 (July 1995): 1-9) presents research indicating that omega-3 fatty acids, specifically DHA, may reduce the risk of depression. The authors associate the increase in depression in North America in the past century with the decline in consumption of DHA during the same period. To lend support to this idea, the authors also note that there are lower rates of major depression in those societies that consume large amounts of fish, a key dietary source of DHA.

Dementia and Alzheimer’s disease

DHA is also being considered as a factor in dementia and Alzheimer’s disease. In 1997, a link between low levels of DHA and Alzheimer’s disease and memory loss was the subject of a conference at The New York Hospital Cornell Medical Center’s Nutrition Information Center. Among the finding discussed at the conference was that a low level of DHA is a significant risk factor for dementia, including Alzheimer’s disease. Further support for this comes from Australia. In a letter published in the Medical Journal of Australia (153 (November 5, 1990): 563-64), Dr. Robert Peers suggests that an imbalance between an excessive intake of omega-6 fatty acids (from vegetable oils and margarine) and a deficient intake of omega-3 fatty acids may be a factor in Alzheimer’s disease.

The Japan Functional Food Research Association has also investigated DHA and dementia. The association notes that those with senile dementia achieved positive results when taking DHA: in 10 of 13 cerebral vascular dementia cases and five of five senile dementia cases, the patients showed more than slight improvements in psychiatric symptoms such as communication, will power, motivation, delirium, the tendency to wander, emotional disorders, and mental depression (www.jafra.gr.jp/DHA2-e.htm).

Vision

DHA is also the major fat in retinal tissue. It plays a strong role in the photoreceptor cells of the retina, suggesting an essential role for DHA in vision. DHA deficiency in laboratory animals shows a marked decrease in proper functioning of the visual cycle.

In a recent study looking at fish oil, which contains DHA, and macular degeneration, researchers found that more frequent consumption of fish appears to protect against late age-related macular degeneration. Only a moderate intake of fish was necessary for the protective effect (Archives of Ophthalmology 118 (March 2000): 401-404).

Bilberry

In addition to DHA, bilberry (Vaccinium myrtillus) is good support for a healthy nervous system. It is closely related to American blueberry, cranberry, and huckleberry. Although its fruit is creamy white instead of purple, it is used in jams, pies, cobblers, and cakes. It was bilberry jam that first spurred interest in this fruit in something other than a culinary sense. During the Second World War, British and American fighter pilots hailed bilberry jam as a secret weapon for improved night vision.

Bilberry extracts are rich in a chemical known as anthocyanoside. These chemicals are powerful antioxidants that appear to have a special affinity for the eyes. Bilberry’s effect may also be related to increased generation of rhodopsin, a purple pigment essential for helping the eye adapt to light and dark. Bilberry appears especially useful in reducing eyestrain and improving night vision—ideal for those who need better “low light” vision and those who do a lot of reading—students and computer operators, for example.

In the 1960s, there were a number of reports to back this up. Bilberry was investigated for its effect on vision acuity in dim light and in night vision in normal subjects, on the progression of cataracts, and on patients with pigmentary retinitis (a hereditary disorder that affects night and peripheral vision), hemeralopia (diminished vision in bright light), macular degeneration, diabetic retinopathy, and retinal inflammation.

Very few studies have been conducted on bilberry since these early studies. Because some of the later studies contradict the earlier studies, more are needed to reconfirm the use of bilberry for vision.

Lutein and zeaxanthin

Lutein and zeaxanthin, carotenoids found in green, leafy vegetables, are also good for the eyes. Like other carotenoids, they are antioxidants. What is unique about these two is that they are the only carotenoids found in the eyes—in the macula (the part of the retina responsible for detailed vision) and the lens. Current research is investigating what function they may serve, and recent studies have found that diets rich in lutein and zeaxanthin may play a role in reducing the risk of age-related macular degeneration and cataracts—two problems that are usually a result of the aging process.

Macular degeneration

Those with the greatest risk for age-related macular degeneration (AMD) tend to have a lower amount of lutein and zeaxanthin in the eyes than those without AMD. In the mid-1990s, one large epidemiological study (a study that looks at a population and charts its general risk) reported that increased consumption of lutein and zeaxanthin reduces the risk of AMD (JAMA 272, no. 18 (1994): 1,410-23).

A study published in November 2000 supports this. In this 140-day study, it was shown that lutein supplementation increases macular pigment—this is important because macular pigment may protect against AMD (Investigative Ophthalmology and Visual Science 41 (November 2000): 3,322-26). This is further confirmed in a report that notes in the abstract that “Some observational studies have shown that generous intakes of lutein and zeaxanthin, particularly from certain xanthophyll-rich foods like spinach, broccoli, and eggs, are associated with a significant reduction in the risk for cataract (up to 20 percent) and for age-related macular degeneration (up to 40 percent).” The author goes on to note that further research is necessary (J Am Coll Nutr 5 Suppl (October 19, 2000): 522S-527S).

Cataracts

Cataracts are the leading cause of vision impairment in the United States and other developed countries. In cataracts, the lens of the eye, which is normally colorless and clear, grows cloudy. The lens is then unable to focus accurately of the retina, which makes seeing more difficult. Interestingly, lutein and zeaxanthin are the only carotenoids generally found in the lens.

There have been three epidemiological studies looking at the correlation between dietary lutein and zeaxanthin and the risk of cataracts. These found a trend toward reduced risk of cataracts and cataract surgery with increased intake of lutein and zeaxanthin (Am J Clin Nut 70, no. 4 (1999): 517-24; Am J Epidemiol 149, no. 9: 801-9; Optom Vis Sce 77: 499-504).

How they work

Although exactly how lutein and zeaxanthin function in the eye is not fully understood, researchers propose that their health benefits have to do with their antioxidant ability and their absorption of near-to-blue UV light.

They absorb near-to-blue UV light, and this type of light is potentially the most damaging light that reaches the retina. As antioxidants, they inhibit the formation of free radicals—this is important because the eye is rich in fatty acids that are easily attacked and damaged by free radicals.

Ginkgo

Ginkgo biloba is another supplement that fights neuro aging. It is perhaps the best-known of the natural substances addressed here. It has also been extensively researched, with studies showing that ginkgo does help maintain mental acuity.

This is largely due to its effect on circulation. Ginkgo increases blood flow to the extremities and the brain—there is actually an increase in cerebral blood flow. It stands to reason that if you get an increase of blood flow to the brain, the brain is going to get more oxygen and more glucose. It is this increased flow of oxygen and nutrients that is the reason why there is significant improvement in patients with some form of dementia.

Ginkgo biloba extract (GBE) has been studied since the 1950s. Studies reveal positive results for what is known as “cerebral insufficiency”: a collection of symptoms that include difficulties in concentration and memory, absentmindedness, confusion, lack of energy, tiredness, decreased physical performance, depressive mood, anxiety, dizziness, tinnitus, and headache. The German Commission E—a group of physicians, pharmacists, and toxicologists who evaluate herbs for safety and efficacy—notes that GBE does lead to an improvement in memory performance and learning capacity.

Since October 1997, when the prestigious Journal of the American Medical Association (JAMA) reported that GBE may be beneficial in the treatment of Alzheimer’s disease, ginkgo has received increased attention. In 1998 and 1999, analyses of previous ginkgo studies noted that ginkgo does positively affect cognitive functions to some degree. A more recent study (Dement Geriatr Cogn Disord 11, no. 4 (July-August): 230-7), looked at ginkgo and dementia in a 26-week, double-blind, placebo-controlled trial. The abstract notes that “In comparison to the baseline values, the placebo group showed a statistically significant worsening in all domains of assessment, while the group receiving GBE was considered slightly improved on the cognitive assessment and the daily living and social behavior.”

DHA, bilberry, lutein, zeaxanthin, and ginkgo. Five substances that add up to common sense for your senses!