Image: iStock.

By: 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. (Post continues after gallery.)

10 foods you never knew were healthy

Bread

KATIE THOMSITT, Dieticians Australia spokesperson says: "Lots of people shy away from bread to achieve weight loss. But bread is such an important source of fibre, and plays such a helpful role in weight loss and preventing bowel cancer. A couple of slices of a dark, seedy bread per day is absolutely fine."

Cheese

KATIE SAYS: "Cheese is definitely a higher fat source of dairy, but still a good dairy fat. Choose low-fat options if you have it regularly, otherwise consume it in moderation. One serve of dairy is 30g, so a couple of slices is absolutely fine."

Chocolate

KARA LANDAU, The Travelling Dietician says: "Studies have been able to show that dark chocolate can improve insulin sensitivity, reduce blood pressure in healthy individuals, protect against heart disease, and improve HDL good cholesterol (not a bad start for such a tasty food!). Dark chocolate also contains polyphenols, whilst white chocolate does not. These polyphenolic compounds are able to relax blood vessels allowing for better blood circulation, and thereby assisting with the maintenance of healthy blood pressure levels."

Coffee

KATIE SAYS: "Coffee is a really good snack, in particular if its milk-based to get the dairy in - for example, a skim latte. As long as its in moderation - daily guidelines say a maximum of three per day! And you want lots of water on top of that."

Eggs

KARA SAYS: "Yes, even the yolks are good for you! Healthy fat soluble vitamins, as well as half the protein found in an egg, are all found in the yolk!"

Avocado

KATIE SAYS: "Avocado is a healthy fat. Lots of people think its high-fat and not good for you, but its rich in mono unsaturated fats, which give you protection against heart disease. It also helps with controlling lower cholesterol levels."

nuts

KATIE SAYS: "Nuts fall into the same category as avocado - they have lots of healthy oils and fibre."

dairy

KARA SAYS: "Often milk and yoghurts are fortified with Vitamin D (a fat soluble vitamin) which requires a small amount of fat to be present in order for the body to absorb it, therefore having the full fat variety can be of value to enhance the nutritional benefits from the products' consumption. The fat in the dairy also aids with satiety, which could prevent unhealthy snacking at a later point in the day."

Potato

KATIE SAYS: "Potato always gets a bad rap as a starchy vegetable, but it's an excellent source of fibre. Sweet potato in particular is great for weight management and sugar level control. Potatoes are also really rich in potassium."

Red meat

KARA SAYS: People tend to restrict red meat unnecessarily, thinking that its high in saturated fat. "But lean red meat is high in protein, CLA (which has been found to be associated with lower body fat percentages), B12, iron and zinc. These are all nutrients we want to get into our body!"

Another American study shows that any two individuals will have genetic differences that translate to differences in 3 per cent to 40 per cent 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.

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. (Post continues after gallery.)

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