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August 2023

What's Eating You? 

You can account for taste: How your dislike of certain flavours is baked into your genes

Love coriander but hate Brussels sprouts? Chances are it’s down to your DNA. 

By Dr Giles Yeo 


‘Don’t you have any taste?’

It is an interesting, if potentially rude, question that encompasses a broad church of possible topics. Are you about to be criticised for your taste in art? Theatre? Books? Clothes or music perhaps? And of course, let us not forget food.

A large proportion of food tastes are acquired. Take the different types of starchy carbohydrates, which make up more than 50 per cent of calories consumed throughout the world. My wife, who is of white Northern European ancestry, loves it in the form of bread.

I am of Chinese ancestry and can take or leave bread. Rice and noodles, however, I can easily eat every single day. The love of carbs is largely universal, but the ‘tastes’ for its different forms are culturally embedded from an early age.

What is less well known is that there are genes that influence our ‘taste’ for certain types of food.

In my lab, we study the genetics of bodyweight, which we now know to be powerfully influenced by how our brain controls our feeding behaviour. One of the key genes that play a role in the control of food intake is the melanocortin 4 receptor or MC4R, which forms part of the circuit in our brain that senses how much fat we are carrying.

This is important because how much fat we have onboard is directly related to how long we would survive without food. We have shown that around 0.3 per cent of the UK population, potentially up to 200,000 people in the country, carry mutations in the MC4R, making them, at 18 years of age, on average 18kg heavier than someone without an MC4R mutation. Of that 18 kg, 15 kg is fat.

Why? Because people with mutations in MC4R have brains that are less sensitive to the amount of fat in their bodies; their brains think they are carrying less fat than they actually are. As a result, they eat more, and end up heavier.

But the MC4R doesn’t only influence how much we eat, but also what we eat. A colleague of mine here in Cambridge, Professor Sadaf Farooqi, devised two different experiments, to try to understand the role that MC4R plays in influencing food choice. She tested lean individuals, and individuals with obesity with and without MC4R mutations

In the first experiment, she gave participants an all-you-can-eat buffet with three options of chicken korma (a mild, sweet, almond-based curry). The three curries were the same, in look, smell and taste, but differed in fat content, which was manipulated to provide a ‘Goldilock’s-selection’ of 20 per cent (low), 40 per cent (medium) and 60 per cent (high) of the calories from fat.

What happened was those carrying a mutation in MC4R ate almost twice the amount of high-fat curry than the lean individuals ate, and 65 per cent more than individuals with non-MC4R obesity.

In the second experiment, the same three groups were given Eton mess, which is, in effect, what happens when someone drops a Pavlova made of strawberries, whipped cream and meringue on the floor, and scoops it back in a bowl.

Again, there were three options from which to choose, this time differing in the amount of sugar present in the meringue and cream, providing 8 per cent (low), 26 per cent (medium) and 54 per cent (high) of calorific content.

Paradoxically, in contrast to the fat choice experiment, individuals with a mutation in MC4R liked the high sugar dessert less than their lean and obese counterparts and in fact, ate significantly less of all three desserts compared to the other two groups. It turns out that people with a defective MC4R preferred higher fat food but had a decreased preference for sugary foods.

How about the taste or distaste for specific types of food? Brussels sprouts for instance?

I once did a talk at the Royal Institution in London about the genetics of feeding behaviour and performed a demonstration with 12 people from the audience. Everyone got a little blank bit of paper and were told to put it on their tongue (I did it too, to reassure that I wasn’t trying to poison anyone).

Half of the volunteers (including me) encountered an acutely bitter taste, while the other half tasted nothing, and were looking around, puzzled by the difference in reaction. What was going on?

Well, all the pieces of paper were infused with a little drop of phenylthiocarbamide, the chemical responsible for the bitter taste found in brassicas, plants in the cabbage and mustard family, which include the aforementioned Brussels sprouts.

However, only around 50 per cent of people, known as ‘supertasters’, carry a variation of the gene TAS2R38, that allows them to detect the bitterness. The ability to taste this bitterness doesn’t automatically mean you hate sprouts, but it certainly influences the taste sensation you get from eating them and other related vegetables.

Then there is the Marmite reaction of different people to the herb coriander (or cilantro, depending on where in the world you hail from), which many people consider tasty (me), but some, famously, the chef Julia Child, find disgusting. This dislike may, of course, simply reflect preference. However, for those coriander-phobes amongst you, for whom the herb has a strong soapy taste, it is indeed genetic.

Some people have a genetic variation in the olfactory-receptor gene OR6A2, allowing them to strongly perceive the aldehydes in coriander leaves, which are the source of the soapy-flavour. Interestingly, the prevalence of this genetic variation varies geographically, with regions where coriander is more popular, such as Central America and India, having fewer people carrying this ‘soapy’ variation.

So next time a dinner companion expresses a like or dislike for a specific food, it could be for cultural reasons, but it could indeed also have a genetic basis. Whatever the reason, it is probably best not to.

How can WHEN you eat possibly make a difference

in your health and weight??

And what is a circadian rhythm anyway?

All of the things that our body does it does at certain times. This is because we can’t do everything at once. We do some things during the night while we’re sleeping like repair our bodies. We do some things during the morning, for example our digestive system gears up to eat when it anticipates we’re going to have the first meal of the day. So when you have your first meal and when you have your last meal affects the rhythm of your digestive system .
Many systems are affected by daylight -- when there’s light in the sky and when it is dark. All systems in your body are infulenced by when you fall asleep and when you wake up. This internal timing system that we have -our circadian rhythm- interacts with light, sleep and food and produces the daily rhythms of our body. Maintaining this system  and keeping it in sync helps us have the best health we can.

As you will learn, having regular rhythms is important. Our ancestors lives were controlled a lot by the sun, but modern conveniences, such as light bulbs, has changed when we are able to do things. Changing when we do things, though, disrupts our natural circadian rhythms. Just living indoors we get less sunlight in the early morning , so we don’t wake up as well. We turn on lights at night, and then we don’t sleep as well. Because we have bright lights when close to bedtime or sometimes lights from screens, we also think we can stay up as late as we want and sleep as late as we want . We change our schedules for the weekends or from day to day. This wasn’t possible when we relied on the sun for as our only light source .

There are three core rhythms: eating, activity and sleep



I used to think that my body was ready 24 /7 to do things like digest food or work or move.

Turns out your body is only ready to digest food for about 8 to 10 hours after the first meal you have in the morning. After that it slows down, it gets ready to do things like cleaning itself . If you eat breakfast really early or really late you throw off the rhythm of your stomach, pancreas , liver and muscles.

If you eat a late dinner the disruption to your body is even stronger because it takes so much longer to digest food when is it outside your optimal 10 hour window. This then delays other processes , like using the fuel we just stored. .
Our bodies can’t store fat and burn it up at the same time . When we eat we store fat and delay fat burning. Then the fat burning process happens later-- maybe by a few hours, and may not finish by the time you eat breakfast. This whole process slows down fat storage and upsets blood glucose . It can contribute to deveolping diabetes. If your eating routine varies a lot it can make it difficult to lose weight because your body is always in fat storage mode doesn't get a chance to be in fat burning mode





When we are not eating or sleeping our body expects to have to do physical activity during the day. Activity improves sleep -even just regular stretching helps sleep onset, sleep quality ,and length of sleepAdd your text here. Edit to add dynamic values like name, email and more.





If you want to adjust your circadian rhythm it works best to start with changing activities in the evening. At the end of this article there is a list of ways to get better sleep.

Count your sleeping time from when you are laying down in the dark no lights and it is quiet. A good night sleep helps you rejuvenate your brain and your body. It helps with alertness for the next day, balances hunger and satiety hormones for more efficient metabolism and synchronises all of your internal clocks.

In the first hour or two after you get up, go outside and get bright sunlight in your eyes (Not of course by looking directly into the Sun). The nature of morning sun is different, it has more blue light and that will signal your brain that it’s time to wake up. It will set your internal clock,. it’s also useful to go outside again in the evening as the sun is setting as there is another signal to your internal clock that now it’s time to wind down and get ready for sleep.

Even if you have the windows uncovered you get much less light indoors than you do outdoors, so being outside is extremely helpful in getting sunlight both in the morning and during the day, both of which will help you sleep.

Stop eating three or four hours before you go to bed so that you are not digesting food when it is time to sleep. Keeping a regular time that you go to bed and that you get up -- with about a half an hour leeway--also helps you sleep well.


Stressors and inflamation

The most common threat to each of your cells is oxidative stress. It occurs when there are extra oxygen molecules in the cell and they produce unstable oxygen molecules. These molecules take electrons from other places, including the DNA the cell membranes and other important parts of the cell. Oxidative stress is an important part of many diseases because it leads to chronic inflammation. It is the most common biological occurrence that underlies chronic disease states such as cancer, heart disease, dementia, arthritis, infection and accelerated aging. One of the primary jobs of the circadian clock is to control oxidative stress .
A strong circadian rhythm, which happens under time restricted eating, supports better repair to the lining of your gut and also your skin. It reduces oxidative stress and the production of too many inflammatory chemicals.
A good mixture of microbes happens naturally even even on poor diet if you are on a 10 hour time restricted eating schedule.  Time restricted eating changes how food is broken down and absorbed in such a way that a lot of the sugars are not absorbed.
In the morning you may find your tastebuds and your sense of smell are more acute after a few weeks of time restricted eating. Some people find that the kind of food with added sugar starts to taste too sweet and they don’t like them as much anymore. As a result they make healthier food choices 
Since time restricted eating reduces inflammation, often diabetes, atherosclerosis, arthritis and joint pain and soreness decrease. Time restricted eating also reduces the storage of extra fat, improves fat burning, and gets cholesterol levels to normalise.

Your circadian rhythm and your brain

New neurons are made in every day at certain time When you don’t have enough sleep or when you get jetlag, fewer new neurons get bmade that day. Your circadian rhythm regulate s genes that repair neurons also, so when your rhythm is disrupted less repair happens. During the day brain chemicals that promote motivation and reward us for doing things are active but in the evening and late night chemicals that support calmness are higher. A disrupted circadian rhythm can change this and makes it harder to be productive during the day and sleep well at night.



9 Ways to get better sleep:

  1. Limit your access to light after the sun goes down, keep lights low, including lights from screens.

  2. Spend time outside during the day, even on cloudy days you will get much more light out side (and this will also improve your mood)

  3. Do physical activity during the day

  4. Use light that is more orange and not blue in the evening

  5. Sleeping in a dark room- if you get up in the night keeping lights low ( Or your eyes have closed)

  6. Only use caffeine before noon.

  7. stop eating 2-3 hours before bedtime-this includes snacks and beverages.

  8. Use table lamps instead of overhead lighting in the evening .and maybe a dimmer in rooms like the kitchen or the bathroom where lights 10 to be bright

  9. Turning down the temperature can help you fall asleep.


ref "The Circadian Code" Satchin Panda, PhD

This is a reminder to add something to link to our site--like if you do an infographic, have a link going to all the other infographics we have (we should make a box or subset of FREE box with infographics

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