Down syndrome was first described in 1866 by John Langdon Down. In 1959, genetic analysis allowed Dr. Jerome Lejeune to determine the cause of Down syndrome. People have 2 copies of each of 23 chromosomes. In Down syndrome, instead of there being 2 copies of chromosome 21, there are 3. This is where the term trisomy 21 originates. Although the chromosomes themselves are normal, the presence of the extra chromosome results in a variety of well-described features and symptoms characteristic of Down syndrome.
One might assume that since Down syndrome is genetic in origin, there is nothing that can be done for individuals with this disorder. The health of people with Down syndrome has been improved by the availability of antibiotics, the switch from institutional care to home care, and advances in heart surgery, which can correct congenital defects that afflict many Down syndrome babies. As many as 80% of Down syndrome individuals are now living to be 50 years of age or more. It is important to recognize that although people with Down syndrome share many similarities, each person is unique. There is help for these individuals through proper medical care, wise nutrition and early intervention.
Much research in the 1980's was focused on the effect of megadoses of vitamins and minerals and their putative effect on IQ and mental functioning in Down syndrome individuals. Most of these studies did not show a beneficial effect, however they were focused solely on supplementary vitamins and minerals. The role of supplementary amino acids was not investigated. Recent work indicates anomalies in amino acid levels in the plasma and the urine of Down syndrome individuals. Furthermore, research has identified specific defects in metabolic pathways in Down syndrome. Nutrients, including vitamins, minerals, antioxidants, and amino acids, play a role in these pathways. In addition, many Down syndrome children suffer from malabsorption, celiac disease and lactose intolerance. Thus all nutrient needs may not be met in the diet alone.
Oxygen is essential for life. However, oxygen can also be a harmful substance in our body. It can be converted to a free radical and cause cell and tissue damage through a process known as oxidation. Oxidation occurs, for example, when an apple exposed to air turns brown and when our cars develop rust from exposure to air and water. In the body, oxygen can ultimately be converted to hydrogen peroxide, which is also a powerful oxidant. An enzyme called superoxide dismutase is responsible for the generation of hydrogen peroxide. The gene for superoxide dismutase is located on chromosome 21 and it has been shown that the activity of the superoxide dismutase enzyme is elevated in Down syndrome. Thus in individuals with Down syndrome, the excess activity of superoxide dismutase may be very damaging. To protect against free radical damage, antioxidants are important. Antioxidants can protect our cells and tissues from this damage by “mopping up” free radicals. Vitamin C, beta-carotene, vitamin E, selenium and glutathione all have antioxidant functions.
In a recent study performed with cultured fetal neurons from Down syndrome individuals, it was demonstrated that reactive oxygen species contributed to apoptosis, a process where the cell programs itself to die. Antioxidants prevented this degeneration of the Down syndrome neurons. These results suggest oxidative damage may play a role in the Down syndrome brain, yet must be interpreted with caution. The neurons were removed from the body and then the experiments conducted. The direct effect of free radicals and antioxidants in the body must now be investigated. This study will hopefully initiate further research to delineate the role of oxidative damage in the aging process and in degeneration of the brain, especially in Alzheimer's disease. This is particularly relevant as all Down syndrome individuals over the age of 35 develop Alzheimer-like neuropathology and between 15-40% fully develop Alzheimer's disease.
Monocarbon metabolism is vital for a variety of biochemical processes. Some of the compounds whose synthesis is dependent on one-carbon metabolism include: adrenaline, choline (as in acetylcholine, a neurotransmitter and as in phosphatidylcholine, an essential component of cellular membranes) and components of RNA and DNA. Monocarbon metabolism involves the transfer of one-carbon units on carriers, which as their name implies, carry the one carbon units to other compounds. One carbon units are derived from common dietary components, serine, glycine, methionine and choline. Carriers for monocarbons include: THFA (tetrahydrofolic acid from the vitamin folate); S-adenosylmethionine (derived from the essential amino acid methionine); and enzyme-bound vitamin B12. Dietary deficiency of these components can give rise to disorders of one carbon metabolism. So important is monocarbon metabolism to the cell that certain antibiotics and anti-cancer agents target this process. Dr. Lejeune, Dr. Peeters and their colleagues identified several defects in monocarbon metabolism in people with Down syndrome. This research was conducted through the analysis of urine and plasma amino acids, experiments with supplemental folate and methionine, and analysis of drug sensitivities.
As described above, advances are being made in the area of nutrition and Down syndrome, particularly in the areas of monocarbon metabolism and cellular oxidation. Additional research is required to fully comprehend the role of nutrients and their potential benefit to people with Down syndrome.
Any nutritional program should be conducted under the supervision of a family physician.
Adapted with permission from literature by NUTRI-CHEM, the manufacturers of MSB Plus, a nutritional supplement for individuals with Down syndrome.
This article first appeared in issue #5 of Down Syndrome Amongst Us