PCRM >> Good Medicine Magazine >> Can a Gene Make Your Diet Work Better? >> Summer 2005
So why do some of us break bad habits easily, while others have a hard time? Is it that diets are just hard to follow? Or is it something within us? In the course of PCRM’s research studies, we have found some answers in an unlikely place: our genes.
Genes control the action of the chemical messengers in the brain. One gene, in particular, relates to dopamine, the key neurotransmitter in the brain’s “pleasure center” or reward system. As dopamine passes from one cell to another, it signals a pleasurable sensation. It is normally triggered by actions that support survival, either of the individual or the species—eating or reproducing, for example. After all, if eating provided no pleasure at all, we wouldn’t eat—and wouldn't live very long. Likewise, if reproducing were a total bore, the species might eventually vanish.
Now, unfortunately, many unhealthful things can cause a dopamine release, too. Smoking, alcohol, and drugs, for example, are popular precisely because they cause the release of dopamine, in addition to whatever other brain effects they have.
Here is where genes come in: Some people have fewer dopamine receptors than other people due to a gene variant called DRD2 A1. If you inherited this gene from your mother or father, it tends to cut the number of dopamine receptors by about one-third. With fewer dopamine receptors, you are likely to feel a bit out of sorts compared to other people. You are also somewhat more susceptible to addictions of many kinds, including overeating, smoking, alcohol, and even drugs, presumably because these substances provide the good feelings that seem not to come naturally.
Working with Earnest Noble at the University of California, Los Angeles, PCRM’s research team did genetic analyses on 70 people with diabetes taking part in PCRM's ongoing study comparing a low-fat, vegan diet to a more conventional American Diabetes Association diet. The ADA diet cut food intake by 500 calories per day for overweight people, limited portion sizes, and required keeping tabs on carbohydrate intake. The vegan diet eliminated animal products and added oils, but placed no limits on calories, portions, or carbohydrate. The study is still in progress, but in a report to the American Diabetes Association’s scientific sessions in San Diego on June 10, 2005, I presented some intriguing findings on the interaction of genes, food, and health.
First of all, we found the DRD2 A1 gene variant in 46 percent of the participants, which is about twice its prevalence in the general public. Second, the gene seemed to affect how well people do on their diets, which became most obvious in participants who kept their medications constant during the first 22 weeks of the study—allowing us to compare the diets without the confusion caused by changing medication regimens.
Among participants without the gene variant (those whose dopamine receptors were “normal,” that is) the vegan diet led to a much greater drop in the primary measure of blood sugar, called hemoglobin A1c (1.4 points), compared to the ADA diet (0.1 point).
However, among those with the gene—and with fewer dopamine receptors—the two diets were much more similar: a 0.3 point drop for the vegans and no drop at all for the ADA group. Here is what we suspected was going on:
With too few dopamine receptors, the brain is not getting the stimulation it needs in order to feel “normal.” So one theory is that such individuals simply find it hard to stay free of substances of abuse, including unhealthful foods.
This from PCRM, which is a pro-vegan anti-meat group, but the link between diabetes and DRD2, the ADD/alcoholism/low dopamine gene is interesting.
So why do some of us break bad habits easily, while others have a hard time? Is it that diets are just hard to follow? Or is it something within us? In the course of PCRM’s research studies, we have found some answers in an unlikely place: our genes.
Genes control the action of the chemical messengers in the brain. One gene, in particular, relates to dopamine, the key neurotransmitter in the brain’s “pleasure center” or reward system. As dopamine passes from one cell to another, it signals a pleasurable sensation. It is normally triggered by actions that support survival, either of the individual or the species—eating or reproducing, for example. After all, if eating provided no pleasure at all, we wouldn’t eat—and wouldn't live very long. Likewise, if reproducing were a total bore, the species might eventually vanish.
Now, unfortunately, many unhealthful things can cause a dopamine release, too. Smoking, alcohol, and drugs, for example, are popular precisely because they cause the release of dopamine, in addition to whatever other brain effects they have.
Here is where genes come in: Some people have fewer dopamine receptors than other people due to a gene variant called DRD2 A1. If you inherited this gene from your mother or father, it tends to cut the number of dopamine receptors by about one-third. With fewer dopamine receptors, you are likely to feel a bit out of sorts compared to other people. You are also somewhat more susceptible to addictions of many kinds, including overeating, smoking, alcohol, and even drugs, presumably because these substances provide the good feelings that seem not to come naturally.
Working with Earnest Noble at the University of California, Los Angeles, PCRM’s research team did genetic analyses on 70 people with diabetes taking part in PCRM's ongoing study comparing a low-fat, vegan diet to a more conventional American Diabetes Association diet. The ADA diet cut food intake by 500 calories per day for overweight people, limited portion sizes, and required keeping tabs on carbohydrate intake. The vegan diet eliminated animal products and added oils, but placed no limits on calories, portions, or carbohydrate. The study is still in progress, but in a report to the American Diabetes Association’s scientific sessions in San Diego on June 10, 2005, I presented some intriguing findings on the interaction of genes, food, and health.
First of all, we found the DRD2 A1 gene variant in 46 percent of the participants, which is about twice its prevalence in the general public. Second, the gene seemed to affect how well people do on their diets, which became most obvious in participants who kept their medications constant during the first 22 weeks of the study—allowing us to compare the diets without the confusion caused by changing medication regimens.
Among participants without the gene variant (those whose dopamine receptors were “normal,” that is) the vegan diet led to a much greater drop in the primary measure of blood sugar, called hemoglobin A1c (1.4 points), compared to the ADA diet (0.1 point).
However, among those with the gene—and with fewer dopamine receptors—the two diets were much more similar: a 0.3 point drop for the vegans and no drop at all for the ADA group. Here is what we suspected was going on:
With too few dopamine receptors, the brain is not getting the stimulation it needs in order to feel “normal.” So one theory is that such individuals simply find it hard to stay free of substances of abuse, including unhealthful foods.
This from PCRM, which is a pro-vegan anti-meat group, but the link between diabetes and DRD2, the ADD/alcoholism/low dopamine gene is interesting.
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