Blame it on mum and dad: how genes influence what we eat

Tasters’ often dislike bitter green vegetables, such as broccoli and Brussels sprouts.

Tasters’ often dislike bitter green vegetables, such as broccoli and Brussels sprouts. Kevin O’Mara/Flickr, CC BY-NC-ND

Nicholas Archer, CSIRO

Hate the taste of Brussels sprouts? Do you find coriander disgusting or perceive honey as too sweet? Your genes may be to blame.

Everybody’s food preferences vary and are shaped by their unique combination of three interacting factors: the environment (your health, diet and cultural influences); prior experience; and genes, which alter your sensory perception of foods.

The food we eat is sensed by specialised receptors located in the tongue and nose. The receptors work like a lock and are highly specific in the nutrients or aromas (the keys) they detect. Sweet receptors, for instance, detect only sweet molecules and will not detect bitterness.

When you eat, your brain combines the signals from these specialised taste (in the mouth) and olfactory (aroma in the nose) receptors to form a flavour. Flavour is further influenced by other perceived qualities, such as the burn of chilli, the cooling of mint, or the thickness of yogurt.

Our unique sensory worlds

Humans have about 35 receptors to detect sweet, salty, bitter, sour, umami and fat tastes. They have around 400 receptors to detect aroma. The receptor proteins are produced from instructions encoded in our DNA and there is significant variation in the DNA code between individuals.

In 2004, American researchers identified that olfactory receptors were located in mutational hotspots. These regions have higher than normal genetic variation. Any of these genetic variants may change the shape of the receptor (the lock) and result in a difference in perception of taste or aroma between people.

Chocoholic? Foodie Baker/Flickr, CC BY-NC-ND

Another American study shows that any two individuals will have genetic differences that translate to differences in 30% to 40% of their aroma receptors. This suggests we all vary in our flavour perception for foods and that we all live in our own unique sensory world.

How much sugar do you add to your tea?

Our ability to perceive sweetness varies a lot and is partly controlled by our genes. A recent twin study found genetics accounts for about a third of the variation in sweet taste perception of sugar and low-calorie sweeteners. Researchers have identified specific gene variants in the receptors that detect sweetness: TAS1R2 and TAS1R3.

There is also high variation in the detection of bitterness. However, the story is more complicated than sweet taste, as we have 25 receptors that detect different bitter molecules. Bitter receptors evolved to detect and stop us from eating harmful toxins. That’s why bitterness is not widely liked.

One of these bitter taste receptors (TAS2R38) controls the ability to detect a bitter compound called PROP (propylthiouracil). Based on the ability to detect PROP, people can be split into two groups: “tasters” or “non-tasters”. Tasters often dislike bitter green vegetables, such as broccoli and Brussels sprouts.

PROP status has also been used as a marker of food preferences, with non-tasters shown to eat more fat and better tolerate chilli.

Genetics has also been linked to whole foods, such as coriander preference, coffee liking and many others. But genes have only a small influence on preference for these foods due to their sensory complexity and also the contribution of your environment and prior experiences.

Towards personalisation

Understanding the influence of genes on taste perception offers a way to personalise products tailored specifically to your needs. This could mean tailoring a diet to a person’s genetics to help them lose weight. Indeed, genetic testing companies already offer dietary advice based on your individual genes.

Foods could one day be formulated for genetically determined preferences.

Foods could one day be formulated for genetically determined preferences. Indiana Stan/Flickr, CC BY-NC

Foods could one day be formulated for genetically determined preferences.
Indiana Stan/Flickr, CC BY-NC

Personalised food products to suit your own genetic dietary preferences are another example. Food products based on personal tastes are already in supermarkets. Salsa can be bought in mild, medium and hot. What if you could purchase food products specifically formulated for your own genetically determined sensory preferences?

Personalisation can also apply at the population level. Food manufacturers could tailor their food products to different populations based on an understanding of how common a genetic variant is in each population.

We are just beginning to understand how genes alter our sense of taste and smell, and how this may affect food preferences. Further research is needed to understand how multiple genes may combine to influence sensory perception and dietary intake. This is no easy feat, as it will require studies with extremely large numbers of people.

Another important research area will be to understand if our taste genes can be modified. Imagine if you could alter your food preferences to consume healthier foods.

The Conversation

Nicholas Archer, Research Scientist, Sensory, Flavour and Consumer Sciences, CSIRO

This article was originally published on The Conversation. Read the original article.


How do your eating habits measure up?

food groups image 1500x752Do you you think you eat enough vegetables to shame a goat? Does your self-restraint when it comes to curly fries make you a smug dinner companion? Or are you an unabashed chocoholic, throwing caution to the wind when it comes to all things cocoa? We all feel varying amounts of guilt and pride about what we eat, but how often do we make an honest assessment of our diet and think about what we could do better?

Well, now’s the time with our new online assessment tool that allows you to measure the quality of your eating habits. Introducing the Healthy Diet Score (HDS).

The HDS is a simple validated scoring system that we hope will help individual Australians measure the nutritional quality of what they eat. The score has been designed to measure whether a person is achieving the food recommendations from the Australian Dietary Guidelines for healthy eating.

Your score will be based on food variety, frequency, quantity and attributes like age and gender. You will receive a Diet Score between 1 and 100 and recommendations on how you can improve your diet.

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The launch of the HDS follows more than three years of research by CSIRO and University of South Australia and is capable of providing a similar evaluation to other more complex diet assessment methods, such as weekly tracking of food intake

Research Director for Nutrition and Health and the co-author of the CSIRO Total Wellbeing Diet, Professor Manny Noakes,  says that often most people overestimate how healthy their food intake is or may not be aware of what amounts of different foods are necessary for good nutrition.

“The online assessment aims to provide guidance on how to improve eating habits and to serve as a reminder that there is always room for improvement when it comes to making healthy food choices.

With most methods to assess eating habits being long and time consuming, we developed the Healthy Diet Score to provide an easy quick and reliable measurement for people to better understand the quality of their diet,” said Professor Noakes.

“A nutritious diet means eating a wide range of foods associated with a healthy lifestyle. However too often people will focus on a single food component or nutrient when looking to improve their diet. We know from previous research conducted that on average people are not eating enough vegetables, wholegrains and dairy foods and are eating too much junk food” said Professor Noakes.

You can watch Professor Noakes talking about the HDS on the Sunrise website.

We will aim to use the data collected from the HDS to help develop better ways to improve national eating habits and integrate it with other research into nutrition and dietary behaviour.

It only takes 10 minutes, so perhaps now’s the time to get your score?

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*Thanks for all your questions and comments about the HDS on this blog and on other channels like Facebook. We’ve tried to answer every single one and have put together a few answers to the most frequently asked questions:

The quiz doesn’t include tea or coffee intake. Was I supposed to include tea in the amount of water I drink?

The calculation and feedback regarding “beverages” is based on the proportion of total beverage intake that is water. The more water you drink compared to soft drink, orange juice, cordial, and sports drinks, the higher your beverage score will be. This is based on the Australian Dietary Guideline (ADGS) recommendations of “drink plenty of water” and “avoid drinks containing added sugars”. For this reason we are looking to include “tea and coffee” specifically in the question about water consumption.

The survey does not include fats used in cooking / vitamin supplements / psyllium / other dietary variations. Will the results be accurate?

The HDS is a measure of compliance against the Australian Dietary Guidelines, which is based on whole foods. This is a short food survey designed as a quick reference tool to assess diet quality rather than a thorough dietary assessment. The compressed nature of this tool naturally has its limitations, however this particular survey has been validated to provide a good estimate of compliance with the guidelines.

Why doesn’t the survey include anything about ‘good fats’ like extra virgin olive oil?

Feedback from the Healthy Diet Score regarding “Healthy Fats and Oils” is based on meat trimming practices and the use of spreads containing unsaturated (healthier) fats. This is based on current scientific evidence that saturated fats increase the risk of heart disease. You are quite right however, that fats and oils used in cooking are not captured in the survey. Again, this is a limitation of having a short food survey designed as a quick reference tool to assess diet quality rather than a thorough dietary assessment.

Why doesn’t the HDS include adjustments for breastfeeding mothers?

We are looking at ways to integrate recommendations specifically for breastfeeding mothers in the questionnaire.

Why aren’t leafy green vegetables included as intake in the calcium question?

The Healthy Diet Score is a measure of compliance against the Australian Dietary Guidelines, which provide advice about the amounts and variety of foods needed to obtain enough nutrients essential for good health and reduce the risk of chronic health problems. It is informed by food modelling (whole diet approach) to find a suitable fit between nutrient requirements, energy intake and food combinations within different age and sex groupings.

While a range of foods provide calcium, dairy foods are still the main sources. Legumes, nuts and some green vegetables may contain some calcium but they do not provide sufficient amounts to meet calcium recommendations. It is possible to meet calcium requirements from non-dairy sources such as calcium enriched soy, almond, rice or coconut milk.

My recommendations include eating more dairy / gluten / nuts. What if I’m allergic or have an intolerance to these foods?

The recommendations at the end of the survey may NOT apply to people with medical conditions requiring specialised dietary advice.

How are the Healthy Diet Score recommendations going to help me lose weight?

The HDS is based on a comparison between your reported dietary intake and the Australian Dietary Guidelines from the Department of Health and Ageing. These guidelines provide advice about the amounts and variety of foods needed to obtain enough nutrients essential for good health and reduce the risk of chronic health problems. It is not designed as a weight loss diet,. However, individuals who habitually eat above the recommendations may experience weight loss by changing their diet to reflect the guidelines.


Eat your way to healthier DNA

We’ve all heard the age-old saying, “you are what you eat”. But is there really any evidence behind this?

It turns out there is.

Dr Nathan O’Callaghan and his team of nutritional experts from our Food, Health and Life Sciences group is helping to reduce our risk of developing chronic diseases like diabetes and obesity through the food we eat.

Nutritional expert and devoted family man, Nathan O'Callaghan and his two little monsters.

Nutritional expert and devoted family man, Nathan O’Callaghan and his two little monsters.

After studying genetics at the University of Adelaide and the Australian National University, Nathan joined us as a post-doctoral fellow in nutritional genomics. Today he leads our team of obesity and metabolic health experts, helping Aussies manage and avoid obesity and its related health effects.

In particular, Nathan is looking at how food and food components interact with our cells, tissues and organs to impact our health.

“The information we can collect is quite amazing – from exquisite details of molecules sitting on top of our DNA, to what the entire Australian population is eating! The challenge is to use what we know to help people optimise their health,” says Nathan.

He is measuring the amounts of particular molecules in people’s bodies to create a ‘picture’ of the way they are functioning. This can help experts determine how certain foods, diets and lifestyle programs might influence our wellbeing. They can do this through a blood test, saliva sample, urine sample and now even a breath test.

An example of DNA damage within a live cell. Image: Glyn Nelson.

An example of DNA damage within a live cell. Image: Glyn Nelson.

The data he collects can also tell us which types of nutrients can help improve our health. In fact, research shows that changing your eating patterns can affect your DNA or genome in just two weeks.

So this raises the question, how can we eat our way to healthier DNA?

Nathan suggests eating a diet high in fibre, fruits and vegetables, with some fish and vitamins can improve our genome and cellular health. Oily fish like salmon and tuna contain high levels of omega 3 fats which can help prevent heart disease.

On the other hand, eating too much processed meat and drinking too much alcohol can actually damage your DNA, age your cells and increase your risk of serious diseases like bowel cancer.

But it’s not all genes and cells for Nathan. Back in 2011 he was a contestant in the very first series of I’m a scientist, get me out of here – an online Australian Idol-style science contest where students vote for the scientists they find the most interesting. Nathan proved to be one of Australia’s most popular scientists, with the highest-ranking overall score for South Australia.

“It was great to be part of the program. I want to inspire the next generation of scientists and give students who are studying science the opportunity to see what we do and how we do it.”

Nathan's adorable little snow bunnies, Tilly (left) and Alfie (right).

Nathan’s adorable snow bunnies, Tilly (left) and Alfie (right).

He’s also a devoted family man and loves to travel with his two kids, Tilly (age 7) and Alfie (age 3). He even took them on a recent work trip to Canada where he was investigating how nutrition during pregnancy affects health trajectory in babies. Now that’s multitasking.

Nathan tweets as @nath_oc.

For more information on careers at CSIRO, follow us on LinkedIn.


How a cheese grater could save your life

By John Smith

Over the past four years a pretty unique feat of architecture has grown on the northern edge of Adelaide’s CBD.  Referred to as the cheese grater, the pineapple, the pine cone, the blue tongue, the mothership and even the air filter, its official name is the South Australian Health and Medical Research Institute, or SAHMRI for short.

But as one of its soon-to-be occupants we’re confident that the research which will take place within its walls, or should we say its ‘transparent skin‘, will be just as interesting, if not more interesting, as the building’s external appearance. Research that will address the most important health issues facing Australia.

So while the building itself may not save lives, what goes on inside certainly will.

Today the Prime Minister and SA Premier opened the new purpose-built home, at an intimate gathering of around 1000 of SAHMRI’s closest friends from the research, health and wider community.

SAHMRI Building

Is it a blue tongue lizard? a mothership? a cheese grater? No it’s the new SAHMRI building.
Credit: CSIRO

 

While we’re not in there yet we’re getting excited as we count the months and weeks til moving day.

Our nutrition and health research clinic will take pride of place right on the ground-level public plaza. This is where many generous volunteers from the community will participate in our studies, testing the effectiveness of lifestyle interventions, such as diet and exercise.

Many of our volunteer studies have been integral to the scientifically supported lifestyle advice in our Total Wellbeing Diet, Healthy Heart Program, Wellbeing Plan for Kids and Diabetes, Diet and Lifestyle Plan books.

Not only will the research we conduct in this iconic building help Australians to make healthier food and lifestyle choices, it will also mean a stronger Australian food industry as we also test the validity of food health claims. These scientifically supported health claims are an opportunity for Australian food manufacturers to gain a competitive advantage in the increasingly health conscious and middle-class Asian market.

We’re always on the lookout for volunteers so if you live in Adelaide you can register your interest on our website. In fact we’re now recruiting for one of our first studies we’ll conduct at SAHMRI, on the effects of vitamin D on cognition.

Each study has different requirements for volunteers, such as age, health, medical conditions etc, so even if you don’t fit the bill on our current studies you might be able to help on future studies.

We’re looking forward to working in this exciting new hub of health research along with colleagues from the universities, hospitals and other health research organisations.

Along with the new Royal Adelaide Hospital currently being built next door and several other planned university and research buildings, our exciting new location promises to be the largest biomedical precinct in the southern hemisphere.

We think what will go on at SAHMRI is important, so forgive us if we be so bold to suggest that our new home should join the likes of the ‘coathanger’ in the club of iconic buildings with unique nicknames.


What the GI?

Are you riding the GI roller coaster?

Infographic about GI