History has seen many food revolutions, movements and ideologies. Ever since Eve bit into that first apple, food has been just as much about beliefs, economy, science, art and all other aspects of society than it has been about fuel for the human body. Now science has taken nutrition to the next microscopic level – human genetics.
Geneticists have had their fingers in the nutrition pie since genetic engineering managed to transfer DNA between organisms, creating anything from virus-resistant squash and herbicide-resistant corn to delayed-ripening tomatoes and non-browning apples. The relatively new field of nutrigenomics thankfully proffers no glow-in-the-dark meals or similar Frankensteinian foods. It is merely the scientific proof of what your grandmother knew instinctively – what you eat can change what you are.
Nutrigenomics, in contrast to genetically modified food, concerns itself not with the genes of foods but with the human genome, that blueprint of human genetics that shot into the limelight in 2000, when it was “decoded”. That is to say, the sequence of units that make up a human’s genetic manual was deciphered like a biological Rosetta Stone. The way in which nutrition can impact the units of the genome, i.e. the genes, is the core study field of nutrigenomics.
In this science of food it takes two to tango and the nutrition-genetics dance can move in both directions. While genes can influence food metabolism and predisposition to diet-related disease, food can influence gene expression. This rhythm and rhyme is repeated in the five main principles of nutrigenomics, which pared down to the bare essentials, go like this:
1.Genes can play a role in disease.
2.Diet can play a role in disease.
3.Genes can be altered by diet.
4.Diet can prevent and treat disease.
5.Individual genetic make-up (genotype) determines the extent of diet-gene interaction.
Your genetic script
To understand nutrigenomics and its other tongue-tying siblings like nutrigenetics, proteomics and metabolomics (see box), you need to appreciate the principles of epigenetics, from which all these categories sprout.
Let’s say your DNA or genome is like the text of a screenplay. You are born with that specific text, the letters and words in that specific sequence. Unalterable and unique to you, it is the determining factor of your individual physical characteristics. That is genetics. But even though you cannot change what is written, you can change how it is written. You can change a word to italics or highlight a phrase in bold. You can make the font larger in a sentence, capitalise a letter or add a few exclamation marks. That is epigenetics.
Co-founder of Fitgenes personalised health provider, dr. Paul Beaver, puts it like this: “It’s true we can’t change the genes we get from our mom and our dad. However, we can compensate for their influence by the foods we choose to eat, how we exercise and our lifestyle choices.
“Our genes interact with our lifestyle choices and that has an effect on the physiological functioning of the body at the cellular level. It impacts on functionings such as inflammation, oxidative stress, cell defence, detoxification and methylation.”
Epigenetics, meaning “above genetics”, comprises anything in the environment that can influence the way your genes are expressed. This includes diet, lifestyle, exercise, environmental pollutants and just about anything else in your daily life. It may just be that your tendency to listen to Baroque music or your multiple body piercings is subtly changing your text, giving new meaning to what is written in your blueprint.
This distinction between genetics and epigenetics is emphasised by Michael Smith, nutritionist of Planet Naturopathy. “That’s the thing with genetics. There’s the genes and then there’s genes expressing themselves.”
He mentions the MTHFR gene as an example. This gene gives instructions for the production of a certain enzyme important for the activation of folate (vitamin B9). Activated folate in its turn drives many metabolic pathways in the body. It is for example involved in DNA synthesis, blood cell formation, tissue repair, neurotransmitter metabolism (important for mental health) and the detoxification of homocysteine, a potentially toxic amino acid associated with cardiovascular disease. A defect in the MTHFR gene could imply defective folate metabolism, with all its corresponding consequences.
“You might have the MTHFR and a lot of people with that genetic variation have high homocysteine and high folate levels and things like that, but that folate is not getting into the cells, it stays in the blood. So that would be that gene expressing itself, it [the MTHFR metabolism] is not working as well as it should.
“Then some people will have the MTHFR gene but they’ll have normal homocysteine. When you do all the tests to see what’s happening in that pathway, it’s all working fine.
“And then they might come across a really stressful life event. They might lose a partner or move somewhere they don’t want to move or do something really stressful, like a stressful job. It will trigger the expression of that gene and everything starts going out of place.”
Coeliac disease, which affects the gastrointestinal tract, works in a similar way. “If you’ve got the [coeliac] gene, you’re more likely to develop coeliac, but you could go your whole life and not have it, but if you went to Asia and developed a bad parasitic or bacterial infection, that could trigger that you then get coeliac. You’re not born with coeliac, you can develop that at ten, twenty, thirty, forty, fifty…”
Having a defective gene or one that is geared towards giving you a certain disease thus does not equate to being diagnosed with that disease sometime in the future. It merely provides the genetic potential. To come back to our example of the written text, you might have the phrase “colon cancer” written into your text, but because it is very small or in yellow or in old Germanic script, it may slip past without being noticed and never be “read” in the play. However, an epigenetic influence like nutrition could change the gene to large, red capital letters, enabling the information it carries to be read or expressed. Eat the wrong stuff and potential turns into reality.
Good food, bad genes
One of the biggest epigenetic influences on health is, not surprisingly, stress. Not only is stress very effective in switching on the bad genes – highlighting the swear words in your text – but stress can also prevent healing when you’re doing everything else right. The effects of good nutrition can be nullified by stress.
Smith confirms that nutrition can indeed reverse or down regulate genes switched on by stress. But for optimal health, you first have to deal with the stress. “Stress is a big trigger for genes and gene expression. You can't have perfect nutrition but have a toxic and stressful lifestyle and [expect to] reverse expressed genes.”
What is just as interesting is that even so-called healthy foods or diets might not be healthy for everyone. It all depends on your genes.
“There is most certainly no one-size-fits-all with diet or supplements,” says Stacey Curcio, naturopath and owner of Gladstone Holistic Health in Queensland. “For example, some people genetically have better insulin signalling, meaning they can handle carbohydrates more efficiently after consumption and thus may be more suited to a Mediterranean diet with grain versus a low-carb, paleo-style diet.”
This puts a big question mark on the ubiquitous fortification of foods with substances such as folic acid (which by the way is a synthetic compound not even identical to the folate naturally found in food). As mentioned above, a genetic variation on the MTHFR gene, so essential in folate metabolism, can cause high levels of folate in the blood that, due to a faulty metabolism, is unable to get to the cells. Adding a substance to the diet of someone who is genetically unable to metabolise it, could cause problems. Curcio finds such fortifications problematic. “How do we know that the population is dealing with this in a positive way given our genetic differences? The answer is, we don’t.”
Cholesterol, a controversial subject at the best of times, also makes a guest appearance in the nutrigenomics drama. Genes can determine how well you metabolise certain fats, says nutritionist Michael Smith.
“You might have high cholesterol and it might be genetically caused. You can bring people’s cholesterol down by looking at their genetic profile. If they’re not metabolising the omega-6’s, which is in a lot of processed food, like in vegetable oils and all your salad dressings – by changing that aspect of food, you can actually bring their cholesterol down.”
In other words, high cholesterol may not be due to a diet high in saturated fat or animal fats, but due to an increased intake of vegetable oils. “Some people can get away with eating a high fat diet, other people can’t. Some genes will work better for a vegetarian diet, others will work better for low gluten.”
Nutrigenomics could be the missing puzzle piece in research controversies. Is coffee good or bad for you? How much vitamin D do you need? Why does the intake of a specific nutrient never give good (or bad) results in 100% of case studies?
A case in point is the varying requirements of vitamin B12 in different people, says Stacey Curcio. “Although studies show that a deficiency of B12 can impair cognitive function in the elderly, not everyone with cognitive decline will benefit from B12 supplementation. Some may be genetically more at risk of deficiency, therefore knowing this early in life and simply monitoring B12 levels can potentially have a huge impact on cognitive function as that person ages.”
Vitamin C can also be affected by genetic variation. While recommended daily requirements are geared to cover all genotypes, some people may have a genetically determined snag in their vitamin C metabolism. Getting adequate amounts of this vitamin should be a high priority in these individuals, to help prevent heart disease and obesity, among others.
Then there is vitamin D. It turns out the required daily intake of this vitamin is written in your genetic script. Says Michael Smith: “Some people genetically don’t absorb vitamin D that well from the sun. Someone might be low in vitamin D and the doctor will say one of the best ways to get vitamin D is to go in the sun, but for some people that’s ineffective and they may need to supplement.”
Another example of applied nutrigenomics is the way the body handles inflammation. According to Curcio, some people are at an increased risk of a pro-inflammatory response. This is a process the body initiates in response to certain stressors, a cascade of reactions that eventually leads to inflammation. “As inflammation is associated with almost every chronic disease, managing inflammation is a priority. Things such as being genetically prone to inflammation, sodium sensitivity and lower CoQ10 levels are important things to be aware of so the patient can modify diet and lifestyle to down regulate these genes and reduce cardiovascular disease risk.”
Genetic profiling might even change the way you look at your daily caffeine fix. Scientists have identified a gene variation in so-called “slow caffeine metabolisers”. These individuals or genotypes are at higher risk of heart attack or high blood pressure and are advised not to drink more than two cups of coffee a day. People without the gene can sip away.
Take the gene test
By this time you might be staring at your plate in terror. What if you’re feeding your genes the wrong stuff, breeding a Frankenstein in your own body? How would you know?
Since cost is also an issue, most nutritionists find that gene profiling is not currently an option for everyone. A generally healthy diet focused on whole foods, with lots of fresh fruit and vegetables, and avoiding processed food, sugar and too much carbohydrate, will still do the trick for most, combined with regular blood tests for cholesterol, vitamins, hormones and others.
But Curcio stresses the preventative nature of nutrition. “Nutrigenomic profiling is empowering a person to make positive changes for the future, rather than simply addressing present dysfunction with a general blood test. The goal is to prevent disease, not react to it. Thus, even healthy people can benefit, as it’s about staying healthy.”
Gene profiling is already available through companies like Remède, Gonidio and Fitgenes. American-based 23andMe is more focused on determining ancestry, but will give you an uninterpreted gene profile which you can take back to your nutritionist for interpretation. All it requires from you is a simple saliva sample.
These nutrigenomics programmes promise increased vitality and prevention of chronic disease by optimising epigenetic factors like diet and lifestyle for your unique, individual DNA profile. By translating your personal Rosetta Stone and making the appropriate changes, you can “talk” to your body on a cellular level to guide it toward its optimal potential.
Enter the era of personalised nutrition.
The bottom line is that “one-size-fits-all interventions in either nutrition or exercise [are] not working,” as Fitgenes’ dr. Beaver puts it. Or as anyone struggling with some stubborn flab knows – if the girl next door with the great body eats chocolate cake for breakfast, the fat will end up on your hips.
Indeed, obesity is one of the health areas where personalised, gene-based nutrition is bound to make the most impact. Small variations in DNA can affect fat metabolism, satiety, energy balance regulation, insulin regulation and inflammation, all of which have been associated with obesity. Your genetic profile even determines which type of exercise suits you best, whether for general health or for weight loss. Nutrigenomics is also being applied in creating better weight loss diets for pets.
Personalised nutrition is where nutrigenomics gets practical and personal. Your gene profile can become the recipe book that determines which ingredients you should or shouldn’t use. Once again, it does not mean that a gene defect will be expressed in your health recipe, but if it’s there, take care. Stress is a meticulous detective, even if something is written in invisible ink.
“We are all going to be the masters of our own health,” predicts Luis Cantarell, president and CEO of Néstlé Health Science SA. “It is a brilliant future, the one that we see for science-based personal nutrition solutions.”
You may not be your own scriptwriter, but you can be your own nutritional text editor. Bon appetit!