A Fortunate Cat Teaches Us About Our Genes (and Ourselves)
My wife Valerie walks our dog Rudy on Sequiota Park trail just down the road from our home near Springfield, Missouri. One day when fall was in in full force here in the southern Midwest, and the leaves in the park at their peak of color, she encountered Beatrice, a silky-haired calico cat, who introduced herself to my wife and Rudy in a laid-back but friendly manner. Beatrice made it known that she had no collar and no home, and that she was ready for some lunch, thank you very much. Her healthy appearance and young age concerned my wife that she had been abandoned in the park. She was cheerful enough, and her patched coat of white and black shot through with burnt–orange seemed chosen just for the season. When Valerie brought the cat home to join our small family it got me thinking about why it is that calicos can only be females and how much the interesting genetics of this cat can teach us about our genes and ourselves. A hot topic in functional medicine is the recognition that genes can be influenced by lifestyle. Although genes, the code of life found deep within each cell, play a role in our health it is estimated that their overall impact is relatively small. The ability to turn on good genes and turn off bad genes is based on the science of epigenetics, and runs counter to the idea that control of our future is determined by our genes.
To learn a little bit more let’s start with a lesson from Beatrice the calico cat. Genetic information is located on paired structures inside every cell called chromosomes. There are 19 pairs of chromosomes in the cat (23 pairs of chromosomes in humans). A mother and father each provide one of the chromosome pairs to their offspring. The chromosomes that determine gender are assigned the letters X and Y. Beatrice is a female cat because she has two X-chromosomes. Male cats have one X- and one Y-chromosome. Because fur color is located on the X-chromosome, and it takes two X’s to make the calico pattern (one X for tan fur and one X for black fur), normal male cats can never be calico. Nature produces Beatrice’s tan and black patchwork by randomly turning off the gene for color on one of the chromosomes while the other remains active. In other words, both fur color genes are present, but only one is expressed. Nature has changed the expression of genes without changing the genes themselves. This is the principle of epigenetics.
How does this happen? The selection of color is accomplished by an “off switch” called a methyl group, a molecule that consists of a carbon atom with three hydrogen atoms attached. It is one of the puzzle pieces needed to understand how we can have so much influence over our genes. When a methyl group attaches to a specific area on the chromosome, a process called methylation, it turns off specific genes. The influence of lifestyle on methylation, it turns out, helps to explain away the idea of genetic destiny. In the case of my calico cat Beatrice the methyl group that turns off one color gene does so randomly. But in human beings the story is different. We are beginning to understand that genetic expression can be influenced. By taking specific steps we can turn on the genes that benefit us, and switch off those that potentially harm us. It turns out that food, movement, sleep, and clean air all influence methylation.
Here are a few examples:
- Eat plenty of folate-rich vegetables. Legumes like lentils, and vegetables rich in folate like spinach, parsley, romaine lettuce, broccoli, asparagus and cauliflower help our body meet its requirements for this essential nutrient. Folate plays an important role in methylation because it is required to synthesize S-adenosylmethionine (SAM-e), the body’s main source of methyl groups. One of the most intriguing roles for folate-driven methylation is the benefit in helping to prevent certain types of cancers involving the pancreas, cervix, stomach, and mouth., , ,  Other powerful foods that have an epigenetic cancer-fighting effect include green tea and soy.
- Exercise regularly. Methylation levels have been found to change significantly after exercise. This includes genes involved in metabolism, energy production, fuel usage, muscle growth, the creation of new blood cells, and inflammation. It turns out these changes occur even after a single bout of exercise. Exercise intensity does appear to make a difference. Consider a program of High Intensity Interval Training involving short periods of very hard exercise (enough to make you feel out of breath) alternated by less intense recovery periods.
- Get enough sleep. Far from a time of inactivity sleep is critical for normal energy metabolism, tissue building and healing, hormone function, immune function, and the organization of memories. Having a good night of sleep depends, in part, upon the function of our internal clock which, in turn, is affected by gene methylation.
- Breathe clean air. Take time to enjoy a walk in the country. While many benefits arise from the availability of methyl groups for gene methylation city traffic exhaust may lower methylation.,  which has been associated with the risk of death from heart attack and stroke.
Humans have an advantage over cats, of course. As we begin to understand the complex science of epigenetics, we learn that we have the ability, in many cases, to manipulate the expression of our own genetic code. The challenge is to learn what exactly constitutes this healthy lifestyle in the setting of “in your face” marketing that too often sends contradictory messages. But when we do we can turn on the genes that benefit us and switch off those that potentially harm us allowing us to rise above our genetic destiny. While we can’t change our own eye color or hair color (at least not without cosmetic manipulation) any more than a calico cat can change her patchwork coat, we just might be on the verge of learning how to thwart disease and live life longer and better. We may not have nine lives, but if we have one long and vibrant one, well…isn’t that almost as good?