Bitter Genetics – How Your Taster Genes Determine The Food You Eat

It is often said that there is no accounting for taste.

Well actually there is.

Taste is one of the few subjective experiences for which there is a relatively neat genetic explanation.

Some molecules in food have shapes that lock into proteins on the surface of your tongue.

That interlocking tells a nerve to fire, sending a signal to your brain that you have tasted sugar, salt, bitter, sour or umami (savory).

But if you don’t have the gene variant that codes for the functioning taste receptor, you can eat as much as you like of the molecule it has evolved to interlock with and you won’t know a thing about it.

There is one gene controlling taste sensitivity that scientists have characterised in a lot of detail – the TAS2R38 gene. This gene (also known as the ‘brussels sprout’ gene) makes a protein that interlocks with a chemical called PTC (phenylthiocarbamide) and gives the taste sensation of bitterness.

PTC isn’t usually found in the human diet, but it is very similar to chemicals found in brassicas such as brussels sprouts, broccoli and cabbages. Because of this, scientists have suggested that the ability to taste or not taste PTC might explain why some people hate sprouts, and some people love them.

The Discovery Of TAS2R38

Ironically, the man who discovered this property of PTC didn’t have a working copy of the TAS2R38 gene. In 1931, Arthur Fox was in his laboratory pouring powdered PTC into a bottle, creating a cloud of the stuff. He was oblivious to the horrible odour, but the chemist on the next bench started complaining.

Intrigued, Fox decided to investigate why some people can taste PTC and others can’t. He got his friends and family to try a little bit of it and tell him what they tasted.

What he found was intriguing: he could predict very accurately whether a person would or wouldn’t be able to sense PTC by looking at how their family had reacted to it. So this ability was very tightly linked to people’s genetics.

This was back in the 1930s and 40s, well before genetic profiling would become possible, and so for many years PTC was used for paternity testing. They assumed that if your father can taste PTC very strongly, and you can’t taste it at all, chances are he isn’t your father.

Of course it’s not completely reliable. Taste is subjective and can be weakened by other things such as smoking, age and what you habitually eat and drink.

It wasn’t until 2003 that scientists managed to locate the exact gene responsible, giving those of us who hate brussels sprouts a genetic explanation for why we should never have to eat them ever again.

The TAS2R38 gene decides if you are a taster or a non-taster.

Studies have shown that around 25% of people are said to be non-tasters, 25% supertasters and 50% medium tasters.

These numbers can vary depending on sex and ethnicity. Women are more likely to be supertasters and so are people from Asia, Africa and South America.

Why is Bitter Taste Important?

Our taste perception plays a key role in determining our food preferences, dietary habits, nutritional status which impact directly on our health outcomes.

Bitter compounds at high concentrations generally elicit food rejection, a behaviour critical to avoid ingesting the many toxic compounds found in foods, such as rancid fat, hydrolysed protein and plant alkaloids.

For those who have TAS2R38 variants (increased bitter taste sensitivity), you are more likely to avoid vegetables rich in anti-tumour and anti-oxidant compounds because of their perceived bitterness.

Instead tasters are drawn towards sweet and fatty foods, potentially increasing the risk of cardiovascular diseases, obesity, and cancer.

Research has also found that non-tasters have fewer taste buds than tasters.

Do You Have The Taster Genes?

Your eating behaviours can contribute to being overweight, which can increase your risk of developing lifestyle and chronic diseases such as Type 2 Diabetes, Insulin Resistance and Heart Disease.

Knowing your taster genes may be especially helpful for anyone who:

• Wants to better understand the influences on their eating behaviours and weight
• Wants to take positive steps towards reaching and maintaining a healthy weight
• Has a family or personal history of type 2 diabetes, heart disease, high blood cholesterol or high blood pressure.

Knowing the genes that may influence your food intake and weight, will help you better understand your body. Your Emed Practitioner can help you choose a gene friendly diet which is tailored to your genetic results – providing better outcomes.

References:

SX Ooi, PL Lee, HY Law and YH Say, Asia Pac J Clin Nutr 2010;19 (4):491-498

Tepper BJ, Koelliker Y, Zhao L et al. Variation in the bitter-taste receptor gene TAS2R38, and adiposity in a genetically isolated population in Southern Italy. Obesity (Silver Spring) 2008;16:2289–2295.