Researchers have spent billions of dollars trying to understand how genes influence the aging process and the risk of disease. Along the way, they have enticed us with promises that gene therapy will someday help cure disease.
But buried in biochemistry books and scientific journalsÑand all but ignoredÑis an effective low-tech approach for keeping your genes healthy and functional. It's simple and costs only about 2 cents a day: just make sure you get enough folic acid, a B-complex vitamin needed to make, repair, and regulate the activity of your genes.
Your genes govern the functions of each of the 70 trillion cells in your body. When a gene is "expressed," or turned on, it sets in motion a chain of biochemical reactions. For example, genes program the biochemical activities needed for a healthy heart, a sharp memory, and a robust infection-fighting immune system.
However, when genes become damaged, they accelerate the aging process and increase your risk of heart disease, stroke, cancer, Alzheimer's, miscarriage, and having children with birth defects. Low intake of folic acid increases the risk of these conditions, largely because it impairs normal gene activity. Conversely, consuming ample amounts folic in foods and supplements helps maintain normal gene function.
Genes Made Simple
If you were to look through a powerful electron microscope, you would find that your genes consist of a double strand of deoxyribonucleic acid (DNA), the molecule that contains your genetic instructions. With still greater magnification, you would see that DNA itself is made from of four chemicals called nucleotide bases. These nucleotide bases form the four letters of your genetic alphabet.
The arrangement of DNA bases, like the letters on this page, provides instructions for making specific proteins and enzymes, which the body uses to make thousands of other necessary compounds. For example, the DNA in a particular gene might program the manufacture of hemoglobin, the oxygen-carrying protein in red blood cells.
You need new DNA when you are growing, healing from injuries, or during the ongoing process of sloughing off and replacing old or damaged cells. Every day of your life, cells make copies of their DNA before dividing and creating new cells.
Folic Acid in DNA Production and Repair
Exactly how does folic acid fit into this process? Quite simply, the vitamin is needed for the body's production of three of the four chemical letters that form DNA.
One of the key ingredients in making DNA is what biochemists call "one-carbon metabolism." Carbon, as you once learned in school, forms the basis of all life on Earth, and one of its roles is in the production of DNA. Folic acid provides and transfers one-carbon atoms needed for synthesizing DNA. If you do not obtain adequate amounts of folic acid from your diet or supplements, DNA production slows downÑand with it, the production of healthy new cells.
Even worse, a lack of folic acid sets the stage for DNA damage. Several years ago, Benjamin C Blount, Ph.D., and his colleagues at the University of California, Berkeley, discovered precisely how this damage occurs. If you are deficient in folic acid, you cannot make adequate amounts of thymine, one of the chemical letters of DNA. In the absence of thymine, DNA incorporates the chemical uracil, which does not belong in DNA.
Meanwhile, various repair enzymes scan DNA looking for errors. These enzymes find the uracil and remove it, but its removal leaves breaks in DNA. These breaks are comparable to missing words, interfering with the instructions in DNA. As this type of DNA damage accumulates, it interferes with the normal activity of genes, accelerating the aging process and setting the stage for cancer, heart disease, and other diseases.
Folic Acid and DNA Regulation
Folic acid also plays a central role in methylation, one of the most basic chemical reactions in the body. Methylation generates "methyl groups," molecules containing three hydrogen atoms and one carbon atom.
Some of these folic acid-dependent methyl groups are involved in what biochemists call DNA methylation. In this process methyl groups attach to various stretches of DNA and suppress gene activity, according to Craig A. Cooney, Ph.D., of the University of Arkansas, Little Rock.
It turns out that selective gene suppression is just as important as gene activation. The reason is that every cell in your body contains a full suite of genes, but not all of the genes are needed. DNA methylation suppresses the activity of more than 1,700 cancer-promoting genes.
Determining How Much to Take
Your folic acid requirements may be influenced by relatively common variations in the gene that programs for methylenetetrahydrofolate reductase (MTHFR), an enzyme that plays a crucial role in how the body processes the vitamin. People with a subtle defect in the MTHFR gene do not use folic acid efficiently and require extra amounts of the vitamin.
A simple blood test for homocysteine will indicate whether your folic acid requirements are being satisfied by your diet. Ideal homocysteine levels are under 7 micromoles per liter of blood. Homocysteine levels above 13 micromoles per liter of blood are a risk factor for heart attack and stroke. Elevated homocysteine levels are also a sign of poor methylation reactions and abnormally low DNA activity.
Folic acid is found in dark green leafy vegetables, such as Boston lettuce, romaine, spinach, kale, and mustard greens. As a supplement, 400 to 800 mcg should be sufficient for most people. However, folic acid is best taken along with vitamin B12 or a B-complex supplement, because these other vitamins also help maintain the health of your DNA and genes.
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