The science of Christmas

Medicinal Christmas trees, the secret of Rudolf’s rosy nose and why your genes could take a bashing over the holiday season. We discover how taking a look at the festive season through scientific eyes could turn your Christmas into a real cracker

Well, it is that time of year again. The shops have been flogging it for months, the kids are in a frenzy and turkeys across the nation have begun exchanging worried looks. Yes, it’s Christmas time. A time to kick back and take stock of the year. But before you dash off to find the sherry and mince pies, let Laboratory News take you on a seasonal tour of the science behind the Yuletide festivities.

Christmas wouldn’t be Christmas without several key ingredients - good food, Christmas trees, presents and of course a certain Mr Claus and his gang of reindeer - and knowing a little about the science behind these seasonal favourites could help you get the most out of the festive fun. Well, either that or it will give you something to impress family members with over lunch.

Let us start at the gastronomic heart of the holiday. Come Christmas lunchtime, the centre piece for many will be a juicy roast, and whatever your choice of meat - or indeed vegetables - it will all amount to a grand fiesta of chemical reactions that few other methods of cooking can match.

Meat is the muscle tissue of the animal, normally consisting of around 75% water, 20% protein and 5% fat and carbohydrates. The proteins in the raw meat are coiled and held together by bonds, so the first job of your cooker - or thermodynamic reactor - is to heat the meat enough so that the bonds break and the proteins unravel or denature. This will make your Christmas meat tender enough for even granddad and his false teeth to manage.

But why does roasted meat taste so good? The answer is the Maillard Reaction. Discovered in 1912 by French chemist Louis Camille Maillard, the reaction occurs when sugar molecules (carbohydrates) are heated with amino acids (proteins). Hundreds of different flavour compounds are formed during the reaction as the carbonyl group of the sugar reacts with the amino group of the amino acid to form N-glycosylamine, which, via a spot of chemical trickery known as the “Amadori rearrangement”, produces ketosamines. It is this group of molecules that produce not only the rich flavours we associate with roasted meat, but also melanoidins, which give that golden brown colouring.

Of course, this time of year is all about over indulgence, but spare a thought for your poor genes as you top up on festive treats. Dr David Topping of CSIRO - Australia's national science agency - warns that over consumption of nutrients can affect your DNA. “There is a school of thought which says that over nutrition leads to the production of molecular oxygen species that can lead to damage of the DNA,” he says. 

Turkey seems to confound this potential genetic onslaught as it is high in dietary protein. “We’ve shown that increasing the amount of protein will increase genetic damage to cells that line the large bowel,” explains Topping. But the Christmas carnivores among us needn’t worry too much - by a stroke of Yuletide good fortune you can avoid this form of DNA damage by eating a specific dietary polysaccharide - commonly known as the potato. Topping says that starch which is not digested in the small intestine can produce protective compounds in the gut that prevent the damage.

Food is not the only source of over-indulgence at this time of year. Sherry and mulled wine are just some of the tipples that are frequently used to lubricate the seasonal merriment. But as we all know, a little too much lubrication can lead to a nasty headache on Christmas morning. A hangover, or as it is technically known veisalgia - from the Norwegian word for “uneasiness following debauchery” (kveis) and the Greek word for “pain” (algia) - is caused when alcohol in the blood stream blocks the secretion of the hormone vasopressin from the pituitary glad. The lack of this hormone means your kidneys will send water directly to the bladder instead of reabsorbing it into the body. This diuretic effect leads to dehydration, which is bad news for your brain. As blood flows through it, water is drawn out of your brain cells and actually shrinks your brain, causing it to pull away from the skull giving you a headache.

But before you get to feast on your chemically reacted turkey, or sup your pituitary confounding tipple, you have to decorate the tree. But do you go real or fake? A fake Christmas tree may be more popular, but here’s a new reason to appreciate the real thing: Researchers have identified a group of anti-inflammatory compounds in the bark of the Scotch pine - widely used as Christmas trees - that they say could be developed into drugs for treating arthritis and pain. The leader of the study, Kalevi Pihlaja, a chemistry professor at the University of Turku in Finland, explains: “The preliminary study showed that highly purified preparations of pine bark extract have potent anti-inflammatory effects. In the future, this may mean that people with arthritis may ease their pain by eating food supplements made from Christmas trees.” The researchers found that the extract not only inhibited nitric oxide production, an excess of which has been linked to arthritis and circulatory problems, but also inhibited prostaglandin production, which has been linked to arthritis and pain.

However, before you grind down your tree to mine its medicinal properties, you need to open the stack of pressies that have been carefully piled at its base. And nothing is guaranteed to spark sibling rivalry more than the annual “who has the biggest pile of presents” argument, but recent studies suggest that even giving Christmas gifts is laced with one-upmanship. Norwegian behavioural biologists have found that eldest siblings spend more money on each gift than their younger siblings. The research also noted that those born in the middle give the least to the family. Dr Iver Mysterud, who carried out the study, thinks that this is because the younger siblings are trying to find a way rebel.

“In a group of siblings there is competition for parents’ attention. While the oldest of the children will often be more conservative and more similar to their parents, so the next in line must choose another strategy to gain attention and resources. Therefore they are often more rebellious,” he said.

He also found that girls give more generously than boys. That women are more thorough in Christmas shopping than men doesn’t sound so revolutionary, but Mysterud also has a possible explanation for this. He suggests that it stems from the female trait of giving gifts to strengthen social ties.

If family members can’t rely on each other to get that perfect present, then there is someone who always knows – provided you have been good of course!
However, last year we told you of the rather worrying scientific argument that concluded Santa is probably dead. Roger Highfield, author of Can Reindeer Fly?, suggests that due to the immense number of gifts that Santa would need to deliver across the globe, and the speeds at which he would need to deliver them, forces 17,500 times greater than gravity would crush him into a seasonal singularity. Despite this, he is quick to point out that “Santa is not dead. He delivers presents every year, as reliably as Rudolf’s nose is red.”

So it seems that science is divided on St. Nick. But how does a rather overweight bearded fellow being drawn by nine caribou get airborne? Theoretical physicist Dr Michio Kaku says that it could be simply down to some cunningly placed magnets and a “can-do” attitude. “Scientists today can duplicate flying in the laboratory using powerful magnets. We can even levitate a train so it appears to float on air. Santa would need room temperature superconducting magnets, which we don’t have yet. But one day room temperature superconductors will be discovered.”

Until that time we will just have to concede that Santa and his arctic laboratory have one over us.

It seems, however, that he has yet to cure the common cold. Rudolf’s nose is testament to that - or at least that is one theory behind the origin of his most famous asset. Reindeer noses contain an elaborate concentration of folded membranes, which act as heat exchangers. Inhaled cold air is rapidly warmed as it enters the body, and exhaled air is cooled before leaving. This helps the animal to retain heat and also reduces moisture loss. However, this moist respiratory system provides a comfortable home to many parasites and bacteria, including 20 that are unique to reindeer. Odd Halvorsen of the University of Oslo suggested some years ago in the journal Parasitology Today that the “celebrated discolouration” of Rudolph's nose is probably due to a parasitic or bacterial infection of his respiratory system.

So what tips can we glean after our look at Christmas through scientifically tinted glasses? Well, firstly when the proud cook triumphantly produces the Christmas feast this year, don’t fall victim to an embarrassing faux pas – be sure to compliment them on their perfectly timed Maillard Reaction.
Also be sure to have plenty of spuds on the go if you want to spare your genome from a foul fate. Secondly, expect a shrinking brain if you get a bit liberal with the sherry, and thirdly if you want to leave a little something for Rudolf on Christmas Eve, you’d be better off with a box of Kleenex and some Vaporub rather than a carrot. Merry Christmas!



By Phil Prime, assistant editor of Laboratory News.