Top Editors ... Nutrition gets personal

Title: Nutrition gets personal
Date: 09/07/2009
Autor: Lynda Searby

The genie is out of the bottle with nutrigenomics, but where will it end up?
Personalised nutrition has been billed as one of the biggest trends of the 21st century. But what exactly is personalised nutrition? How can mass produced products be personalised? And isn’t nutrition personalised already anyway, in that everyone’s diet is different?
“Personalised nutrition is the concept of adapting food to individual needs,’ writes Dr Martin Kussman, group leader functional genomics, Department of BioAnalytical Sciences, Nestlé Research Center, in the paper Nutrigenomics and personalized nutrition: science and concept. He goes on to point out that food personalisation is not a new concept –food choices have always been rooted in personal preferences and individual experiences. And at a certain level, personalised products already exist, ie gluten-free products for coeliacs, heart healthy spreads for people with high cholesterol, and sports recovery products for athletes.

However, such products address the requirements or preferences of specific consumer groups and are based on empirical consumer science. While there’s nothing wrong with this, what such foods do not take into account is that not everybody responds to what they eat in the same way – what’s good for one person isn’t necessarily (as) good for another. “Taking the example of fat, people’s cholesterol levels are only about 10% determined by diet – after that it’s about lifestyle, environment and genes,” says Dr Siân Astley, European communications manager with the European Nutrigenomics Organisation (NuGO). “Although it may seem impossibly complicated, nutrigenomics and systems biology are the ideal –and perhaps only – tools which will enable us to answer the question of what we should be eating.”

What is nutrigenomics?
“A vigorous hike activates hundreds of genes. Similarly, an energy bar consumed at the top of a trail will also affect the way genes are expressed. Whether you’re flexing a muscle or nourishing your body, biochemical reactions occur at the cellular level and these reactions are controlled and influenced by your genes,” explained Patricia Lucas-Schnarre, vice president, product development and marketing, at WellGen Inc. “The science of nutrigenomics seeks to understand how the food we consume exerts an impact on the functioning of our genes.”

Nutrigenetics vs nutrigenomics Nutrigenomics is closely linked to nutrigenetics, but the two should not be confused. Dr Kussman offers the following explanation for differentiating between the two: “Nutrigenomics asks how dietary components influence gene expression, while nutrigenetics asks how our genetic make-up makes us respond to our diet.”
In other words, nutrigenomics is about understanding how the body responds to foods, whilst nutrigenetics studies how variations in genes can affect an individual’s reaction to specific foods.

Nutrigenetics in action
Genetic variations occur that can impact on an individual’s predisposition to react to certain foods. Thanks to nutrigenetic science, individuals with a particular version of a gene can be given specific guidance on how to alter their diet in response to particular clinical symptoms. Dr Astley gives the example of phenylketonuria (PKU) to demonstrate how the science of nutrigenetics has been applied in medicine for some years. PKU is a genetic disorder which results in a patient’s inability to metabolise the amino acid phenylalanine, leading to a build up of phenylalanine and its metabolites within the body. “This can lead to brain damage, and the only solution is to eliminate this amino acid from the diet,” she says.
There are now 20 genes for which a specific relationship has been identified between that version of the gene, a substance in the diet and the risk of developing a particular disease.

Nutrigenetic testing
There are already a number of US businesses that offer ‘nutrigenetic testing kits’ based on this knowledge. They require the consumer to submit a DNA sample for testing and, in some cases, a lifestyle and diet questionnaire. The DNA sample is mailed to a laboratory and the results are returned to the consumer with advice about how dietary intake can be modified to fit their genetic profile analysis.
Some of the criticism surrounding these genetic tests relates to both the lack of regulation of the testing laboratories and the specific advice they offer.
Another problem with this approach, according to Dr Astley, is that these 20 genes only represent 0.1% of human genes. There are 26,845 genes in the human genome.
“If someone has a particular version of a gene that puts them at risk of a heart attack and they change their diet to mitigate that risk, you don’t know what impact that will have on the other 26,844 genes,” explained Dr Astley. “For example, we know there is a particular version of a gene responsible for transporting fat around the body which means individuals are at risk of heart disease. If you change the type of fats individuals with this gene eat, you reduce their risk of heart disease. The problem is that we now understand that people with that version of the gene are also at greater risk of developing Alzheimer’s. What we don’t know is if changing the diet in a way that reduces their cardiovascular risk also reduces their risk of Alzheimer’s, or whether there is the potential to increase it.”

Nutrigenomics to the rescue
This is where the science of nutrigenomics comes in. Rather than looking at a singl gene and individual compounds, nutrigenomics aims to understand how the whole body responds to real foods, by looking at genes, or proteins, or metabolites – or all of them together. “We’re recognising that it’s bigger than how diet affects our genes – it’s also how it affects the proteins that are produced as a result and how those proteins affect our
metabolism,” said Dr Astley.

Advances in science
Hypothesis-driven research or ‘bottom-up studies’ are often used to study the impact of nutrients on gene function. Using this approach, for example, INSERM (the French National Institute for Health and Medical Research) has demonstrated that lipid components can affect several aspects of Metabolic Syndrome (MS), through modulation of the anabolic/catabolic pathways, inflammation and metabolic stress. “MS is a cluster of the most dangerous heart attack risk factors: diabetes and pre-diabetes, abdominal obesity, high cholesterol and high blood pressure,” explained Dr Jean-Charles Martin, research scientist at INSERM. “People with MS are twice as likely to die from, and three times as likely to have, a heart attack or stroke compared with people without the syndrome. They also have a five-fold greater risk of developing type 2 diabetes. “Nutrition is one of the most important external factors that contribute to promoting or preventing the outcome of MS. This can occur through the direct or indirect modulation of genes and gene products by macro or micronutrients.”

The three ‘omics’
The other methods scientists are using to study modulation of gene expression by food are the ‘top down strategies’ ie data-driven hypothesis using ‘systems biology’. This is the world of post-genomic technologies: transcriptomics, proteomics and metabolomics.
The transcriptome is the complete set of RNA (ribonucleic acid) products (similar to DNA) that can be produced from the genome, and transcriptomics is the study of the transcriptome. Just as the entire DNA sequence is called the human genome so the full complement of proteins in a cell or tissue is called the proteome.

Proteomics is the study of the proteome, and attempts to determine the role of the proteins found in cells, tissues or an organism at any one time. Metabolomics (or metabonomics) examines the whole metabolism, which ultimately reflects the behaviour of different patterns of genes. Thus, while transcriptomics and proteomics do not tell the whole story of what might be happening in a cell, metabolic profiling can give an instantaneous snapshot of the physiology of that cell.
Hundreds of studies using these approaches are currently underway. One of NuGO’s goals is to encourage institutes across Europe to share this data.

How can the food industry use nutrigenomics? Whilst there are food and ingredient companies that claim to be using nutrigenomic technology, the scientific community argues that research is not yet at a stage where it should be used as a basis for commercial product development.
“People just talk big at the moment,” said Jeremy Nicholson, Chair in Biological Chemistry at Imperial College in the UK. “The fact is that it is too complex to be applied at present. We are trying to find out why people vary in their response to foods. The obvious future application is in probiotics and prebiotics as these can retune your personal gut bugs, but everyone is different and one size does not fit all.”

Whether we will ever see nutrigenomic food products on supermarket shelves remains to be seen. Major food and ingredient companies like Nestlé, Unilever, Danone and DSM are reported to be investing in nutrigenomics. That said, Chr. Hansen’s R&D department told Food & Beverage International that it was no longer involved in nutrigenomics research.
There are obvious challenges with bringing to market personalised food products.
“The food industry can provide special products for groups of people such as diabetics and coeliacs. At the individual level it is a long way off due to the huge challenge in making individual products and distributing them to consumers,” said Dr Pernille Baardseth, principle research scientist at Norwegian food research institute Matforsk.
Dr Kussman predicts that it is most likely that nutrigenomics will result in foods customised to specific consumer groups: “Eventually, the nutrigenomics-rooted concept of personalised nutrition may translate into the development of new food products that target, if not individuals, at least groups of people with similar metabolic phenotypes and genetic risks,” he writes.
Dr Astley, on the other hand, believes that the most likely manifestation of
nutrigenomic science will be to underpin public health advice.

“At the moment we tend to say eat less and move more, but we know that ‘one size fits all’ doesn’t work for everybody. It’s a simple fact that some people may need to eat much less and move much more, in which case they need much better advice about what it is they should be eating and I think nutrigenomics will enable us to do that much better,” said Dr Astley. “A few years ago the UK Food Standards Agency issued advice about oily fish, which recommended that men, boys and post-menopausal women could eat up to four portions a week whilst girls and women of childbearing age should limit intake to two. I think we’ll see more public health advice that is tailored to a particular population which, for whatever reason, may be vulnerable to disease or need to change their lifestyle in some way.”
Whilst nutrigenomics potentially offers opportunities for tackling health issues such as obesity, it is not without its problems. For example, Susan McGinty, of London South Bank University in the UK, questions whether the health claims regulatory frameworks that are currently being set up will be fit for purpose in the era of personal genomes and personalised healthcare.
“The emerging degree of interethnic and inter-individual variation represents a challenge to a pan-EU register of health claims, whose legitimacy is based on the premise that a healthy, balanced diet will provide a healthy person with all the nutrients they need – and that there is no reason why nutritional recommendations should not apply to all EU citizens equally,” she says. Nutrigenomics could prove to be the biggest breakthrough nutrition science ever, or it could create more problems than it will solve. Either way, the next decade is going to be an exciting voyage of discovery.