Nutrigenetics is the theory of how genes interact with certain food ingredients. Each person is unique in their genes and responds differently to certain foods, and this budding industry promises to recognize what foods the body tolerates and which ones it doesn’t on the basis of genes.

It sounds like science fiction or technology of the future, but nutrigenetics is already a pervasive part of our everyday life. As early as the 1960s, the nutrigenetic testing of newborns for phenylketonuria disease began. Phenylketonuria is a disease in which, due to a genetic defect, the body is unable to break down the amino acid phenylanine. If the illness isn’t recognized and a child’s diet isn’t adjusted accordingly, physical and mental disabilities will develop. Therefore, for the last 50 years, every newborn child in many places, including the U.S., has been tested for the presence of this disease.

We also often hear the term lactose intolerance. This is also a genetic disease, so those who eat lactose-free in relation to symptoms eat according to their genes. If you’re a symptomless carrier of lactose-intolerant genes, you’ll be able to drink milk all your life, but your children may inherit the intolerance from you.

Gluten intolerance is another dietary issue that can only occur if you have certain genes. Without those genes, the probability of developing gluten intolerance is next to zero. A nutrigenetic diet — that is, eating according to individual genes, has long been a part of our life and is far from a thing of the future.

Although the number of skeptics and opponents is decreasing, there are still many who don’t trust the process of genetic testing and analysis.

We often hear from people that they would never undergo genetic testing, but they probably don’t realize that their first nutrigenetic analysis for PKU illness was performed shortly after birth. Their children were also nutrigenetically tested without anyone asking for permission. For decades, this has been a standard procedure that helps prevent physical and mental disability through a modified diet. Each of us underwent our first nutrigenetic analysis shortly after birth.

Most critics of this issue don’t even know what a nutrigenetic diet actually is. They believe that it’s a comprehensive genetic analysis that presents extremely detailed information about some nutrients. They don’t know that the most common food intolerances, such as lactose or gluten intolerance, fall into the nutrigenetic diet category.

The “I don’t want to know” approach is another one we encounter, especially in healthy people. A person who unconsciously suffers from intolerance to gluten and, like the majority of affected people, lives for 10 years without proper diagnosis, would normally want to know the cause as soon as possible.

We also often hear that there haven’t been enough studies on this topic. The argument that “It’s too early and there are not enough studies” is outdated, but would’ve been more valid sometime around 1995-2000.

In 2001, the Human Genome project ended. That’s when, for the first time, we read and published the entire human genetic code. This opened the door to an incredible amount of genetics science and a whole new research industry emerged called nutrigenetics. Two years later, the genetic cause of lactose intolerance was discovered, and shortly thereafter the genetic cause of gluten intolerance.

Today, nutrigenetics is taught at every major university. The number of publications on genetic variations has increased exponentially. Today, we have more than 300,000 publications in the database that investigate the effects of frequently occurring genetic defects. We already know the health effects of more than 80,000 different genetic variations and more than 300 studies have been carried out; For example, on the genetic variation of the COMT gene. For the sake of comparison: in health genetics, if three large studies have been carried out that investigated and proved the same, this fact is considered scientifically substantiated. For the COMT gene, we have over 300 studies. The time when it was possible to say that we don’t have enough studies is long gone.

Do we know everything about genetics? Not at all. But we know a lot about many aspects of it.

So why are there still people who claim that there is little scientific research? This has to do with the rapid development of the field. Those who went to university before the year 2000 didn’t learn anything about this field, and anyone who doesn’t stay updated will quickly lose sight of where science is at the moment. I’m sure these people don’t know that there are more than 300 studies on some genetic variations.

If you do get tested, what can you find out?

There’s plenty that you can learn about yourself from genetic testing. For example, you might find out that phase 1 detoxification enzymes — genes responsible for starting to destroy carcinogens like smoke — don’t work properly. If you’re a smoker, you’ll be at a 3.4-times higher risk of lung cancer than many other people.

Phase 2 detoxification genes are responsible for toxins like heavy metals such as cadmium, lead and mercury, but also from herbicides and pesticides, which are sprayed on crops to remove weeds and pests. Restricting your intake of heavy metal foods; like saltwater fish and shellfish; and getting plenty of minerals that bind heavy metals; like calcium, zinc and selenium; is recommended if your body has trouble breaking those toxins down. If your body has trouble properly disposing of weed and insect remedies, you should also eat organic foods.

If you have bad cholesterol due to your genes, omega-3 (fish oil) capsules are a common recommendation. But in some people, this has just the opposite of its intended effect effect due to their genes and can worsen cholesterol levels. Phytosterols, which come from plants, might be a better fit for those who fall into that category.

Depending on their genes, someone could also have a several times higher risk of Alzheimer’s disease. In addition to other preventative measures, diet can play a big part in prevention. Studies have shown that antioxidant-rich foods can significantly reduce the likelihood of the disease. In at least one study, drinking 3-5 cups of coffee a day was associated with a 65 percent lower risk of Alzheimer’s/dementia later in life.

The secret of coffee…

Coffee is an excellent example of a food that people react very differently to. On the one hand, coffee is one of the healthiest foods we know. No other food has such a high concentration of antioxidants and other healthy substances. But coffee also contains potentially harmful caffeine.

People have a specific gene, CYP1A2, which recognizes and metabolizes caffeine. If a person’s body processes caffeine slowly, it can increase the risk of various illnesses, such as heart disease and osteoporosis. The thing is, only about 52% of people in Central Europe have a functioning version of this gene and are able to process it quickly. That means the benefits of coffee’s antioxidants and other good qualities are highly dependent on a person’s genes.

For example, we know from studies that breast cancer appears on average seven years later in women who drink 2-5 cups of coffee a day compared to women who don’t drink coffee, so may be a significant protective factor against breast cancer. But this effect was only seen in women who had a functioning caffeine-degrading gene and could metabolize it quickly. If this gene didn’t work properly, drinking coffee had no influence on the development of breast cancer. So the protective effects of coffee only seem to occur if the body is able to process it efficiently.

The question now is: can coffee be recommended? For people with a fully functioning gene, the answer is clearly yes. But for those with limited gene function, drinking coffee raises the risk of heart attacks and other illnesses. Therefore, there’s no cut-and-dry recommendation for everyone — that’s why we do DNA analysis.

Genetics and histamine intolerance…

Histamine intolerance doesn’t mean that your body is sensitive to histamine — a substance involved in routine bodily functions like digestion as well as the body’s inflammatory responses after an injury or allergic reaction — but that your body has too much of it. That can either happen when your histamine levels get too high or when your body can’t break it down properly.

The human immune system produces histamine, but it’s also present in food. Thing is, the body has to break down the histamine in food before it’s actually absorbed into the body. There are two safeguard mechanisms for this.

The first protective mechanism is the DAO gene, which produces a histamine-degrading enzyme that’s present into the intestine (where most histamine is disposed of). But if histamine is absorbed into the body, there’s the HNMT gene, which recognizes and breaks down the histamine.

We now know that some genetic variations or defects in the DAO gene lead either to too low of a production of the DAO enzyme or to the production of defective enzymes, and approximately 50 percent of people with histamine intolerance have a low level of DAO. Such genetic variations are therefore a significant risk factor, but genetics is not the only factor here. Our laboratory examines whether histamine intolerance can be caused by any genetic variation in HNMT.

What else will the future of nutrigenetics bring?

At the moment, we are experiencing extraordinary growth in preventive genetics and nutrigenetics, but much more is possible today than what’s actually being used. The most comprehensive nutrigenetic programs analyze more than 50 genes and provide very accurate nutritional recommendations, but the number of genes that affect how we respond to certain foods will grow steadily and our findings will be better and more accurate.

In our laboratory [FITGEN SE in Prague] alone (we have more than 1,000 worldwide), 200,000 analyses have been performed, and the trend continues to rise. Of course, not every medical practice and nutritional counselor uses nutrigenetics, but the progressive ones are already turning to us.

At the moment, our laboratory can detect 111 different illnesses right after a child is born, but the potential is even greater. And it’s already clear immediately after birth which foods children are tolerant of, making it possible for parents to adjust their children’s diets according to their intolerances from the start.

We think and hope that insurance policies with start to take over the costs of genetic analysis and prevention. At the moment, it’s a private service, but these technologies should be available to everyone as a tool to help them maintain good health. Perhaps 20 years from now, we’ll be able to analyze the entire genome of every child right after birth at the expense of the state.

František Zámola, MD, is an expert in sports medicine, sportsgenomics and nutrigenomics, and a physician at the Military University Hospital in Prague.