Eating a Rainbow


I have always been interested in food, but in recent years I have become more conscious (most of the time!) about what it is I’m putting into my body. This led to a lot of research over a long period of time around what is and is not good for your body, how to tell, and in what quantities. A phrase I have repeatedly come across is ‘eat your rainbow’. As a borderline vegan, this is quite an easy feat for me, I love fruit and veg and they are the star of most of my meals. However, I thought I would share the benefits of eating a variety of different coloured fruit and veg, and that eating more of a rainbow can bring to anyones diet.

I began this article wanting to explain why all these foods can have positive effects, however it would end up a short (or even long) novel! Therefore, I have settled for telling you what benefits different coloured foods can have, and examples of each. As each different colour of fruit and veg (natural foods) relates to the quantities of antioxidants, vitamins and minerals alongside pigments it contains, eating a variety of different coloured foods gives your body a huge amount of different antioxidants, vitamins and minerals. All of which nourish your body. It is recommended that you eat at least 3 different colours of food at every meal, as these different colours play different roles within your body – this may be aiding your immune system, digestion, or contributing to the strength of your bones. These fruit and veg are nutrient dense and contain a whole load of fibre, both of which will do your body a lot of good!

So while technically this post is a little unorthodox, and not entirely biology related, I’ve figured that it relates to the benefits we can get from our foods, all due to biological processes. I apologise to any hard biologists who find this slightly insulting …. but if anything I think it is an interesting topic, which many people are not hugely educated on!


Red foods are packed with phytochemicals such as lycopene, and thus help improve heart and circulatory health alongside memory. For instance, cherries are high in antioxidants which can help protect against heart disease, diabetes and arthritis. Red bell peppers are high in vitamin C and fibre, and have been linked to increased immunity, improved digestion and to lower cholesterol. Tomatoes are also notably high in lycopene, and have been shown to reduce damage done to our cells, and decrease the risk of diabetes.


These tend to be particularly high in antioxidants such as vitamin C and carotenoids. Orange foods have been linked to skin and eye health as well as increased immunity and a healthy heart. Carrots for example, are high in vitamin A, helping to maintain the integrity of the skin and oranges are high in vitamins A and C, again linked to increased immunity, heart health and healthier skin. Oranges also have a high magnesium content, which can help strengthen bones and improve digestion.


These commonly contain nutrients which promote good digestion, and as they are high in alpha and beta carotenes, have been linked to improved immunity, healthy eyes and skin. Examples of these are in pineapple, which is cholesterol and fat-free, and high in bromelain. Bromelain, is an enzyme which helps to regulate and neutralise body fluids, aiding digestion. Yellow peppers are also high in vitamins C and A, aiding the immune system and contributing to healthy skin.


Green foods are definitely my favourite, and anything with spinach, avocado or kale in is a winner for me. These contain phytochemicals such as lutein, and have benefits such as improved eye health and strong teeth. Spinach is high in antioxidants and vitamin K, which helps to strengthen bones, while broccoli is high in calcium and iron, linking it to stronger bones and muscles. Kiwi however, is high in folate and vitamin E, which help to decrease the risk heart disease.


These are brightly coloured due to anthocyanins, which have anti-acing properties in the body. They can help promote bone health and have been shown to improve memory and increase urinary-tract health. Although, the main benefit of purple and blue foods is increased circulation. Blueberries for instance, are high in fibre, vitamins E and C, antioxidants and are sometimes referred to as a ‘superfood’. They have been linked to an improved cholesterol and a boost in brain activity. Blackberries are packed with vitamin K which promotes calcium absorption and bone health, alternatively eggplant is high in phosphorus and calcium, again promoting strong bones and teeth.


Hopefully this has made you think about what colour the foods that you eat are, and the benefits that expanding your diet and ‘eating a rainbow’ can have. Hopefully when you sit down for dinner tomorrow there will be a little less beige, and your plate will look a bit more like a rainbow!

sources: as I mentioned, much of this has come from a notebook I have been adding to for a long time, so the exact sources I am not entirely sure of. However, I have found some interesting websites containing similar information.


Why does Christmas dinner make us sleepy?

I hope you all had a lovely Christmas, and are looking forward to the New Year. At about 5pm on Christmas day I looked round our living room to see my sister, dad and grandparents all fast asleep – the annual post Christmas lunch nap. Something which caused me to ponder why, so I thought I’d do a bit of research and share it with you in a quick blog post.

Initially, the only answer I found was that large meals obviously take a long time to digest, thus blood is diverted away from other body areas to help digest the food at a faster rate. However, after a bit of digging I found some interesting websites and articles which gave more in-depth alternatives. The conclusion I came to is as follows…

Eating triggers the PNS  (parasympathetic nervous system) responsible for preparing the body for rest and increasing the activity of the digestive system. The PNS is part of the autonomic nervous system (thank you 3rd Form biology!) which is responsible for involuntary actions. Fundamentally, the actions of the PNS trigger hormones and neurotransmitters which are what make us feel sleepy.

An old New Scientists article says that ‘high blood glucose levels, similar to those after eating a big meal, can switch off the brain cells that normally keep us awake and alert.’ Additionally to this, high blood glucose levels cause the PNS to stimulate the pancreas to produce insulin – converting these sugars to be stored.  This increased level of insulin consequently stimulates the action of tryptophan, an essential amino acid within the brain. In turn, when the tryptophan is in the brain, it leads to an increased level of serotonin – the universally known ‘happy hormone’. Serotonin is an neurotransmitter which passes electrical signals between connecting neurones, and has many functions, including controlling mood and lethargy. Around 90% of serotonin within the body is found in the abdomen, and is responsible for regulating intestinal movements. However, the remaining 10% is found in the brain.

In short, high blood glucose levels trigger the production of insulin. This stimulates the action of tryptophan in the brain, consequently triggering an increase in the levels of serotonin within the body.

Therefore, it is the increased level of serotonin, responsible for mood and ‘sleepiness’ which makes you feel like all you can do is nap after Christmas dinner!



The Marine Iguana – what makes it so unique?


Similarly to thousands of others across the UK on a Sunday night, I was encapsulated by David Attenborough’s new TV programme, Planet Earth II. It was an hour which spiked my curiosity about one reptile in particular, the Marine Iguana, endemic to the Galapagos Islands. It caused me to take a look at what makes these so special, and so different from land iguanas.

These animals are not the prettiest, scaled and ancient in their appearance, however they do have some amazing ecological adaptations, making them truly unique. Surprisingly, despite their scary appearance they are herbivores, feeding as the only sea going lizard in the world [2]. Living on land but feeding in the oceans, Marine Iguanas feed on seaweed and algae, diving up to 30m and holding their breath for around 45 minutes [4]. As this is a habit unique to Marine Iguanas, it provides them with an abundant food source, allowing them to thrive on the Galapagos Islands [2]. Interestingly, it tends to be the male iguanas who feed under the surface, with female and young iguanas feeding on the algae from rocks on shore [3] – something I find somewhat chivalrous.

The temperature of the waters around the Galapagos islands mean that Marine Iguanas can never spend too long in the ocean, returning back to the warm of land as they are ectothermic, meaning they cannot regulate their body temperature, unlike mammals and birds [3]. This makes them much more reliant on the temperatures of their environment, warming in the sun and cooling in the shade – when it is cold, they move slowly until they have warmed up enough to feed, and when it is hot they actually physically cover each other for shade. At night, when the temperatures of the Galapagos Islands drop considerably, they gather in vast numbers to conserve body heat [3]. The temperature endurance of an iguana is truly remarkable, when feeding then can lose up to 10˚C of their body temperature [3] – a change which, in humans, can be fatal. For these exceptional animals, they merely bask in the sun to warm up.

So what is it that makes Marine Iguanas so exclusive and adapted to their environment? It’s their long and muscular tail, which moves in a sinuous motion to act a propeller, pushing them through the ocean similarly to crocodiles [3] and razor sharp teeth to scrape algae off rocks. They also have tremendously sharp claws to help them cling to rocks on shore and underwater, withstanding heavy currents – another adaptation to help them feed. However the adaptations don’t stop there, due to the salty nature of the seas, they even have salt glands connected to their nostrils which clean their blood of extra salt accidentally ingested whilst feeding underwater [1].

Almost every shoreline of the Galapagos Islands is scattered with Marine Iguanas, but these mysterious creatures differ from island to island. Marine Iguanas show their exceptional colours as they mature, with coal black young maturing into red, black, green and grey iguanas [2]. The most colourful of these is the Española Marine Iguana, who have earned the nickname ‘ Christmas Iguanas’ due to their festive colours. Breeding season, which varies again from island to island also has an impact on the colourings of these reptiles, predominantly the males. During this time, the males develop red patches, on ‘Hood Island’ the male will turn completely red, in order to attract a mate and appear the most superior [3].

These entirely unique creatures, found in such a small part of our world have some amazing feeding adaptations and as the only sea going lizard in the world, every effort should be made to preserve their species and environment. I think their behaviour is truly remarkable.


The Giant Panda

image104I am an undoubted and avid Giant Panda lover, whether it be how much I secretly want to be able to eat and sleep all day or my desire to preserve such a species so close to extinction, I’m not entirely sure. Therefore, I deemed it only fitting that my first blog post should be about these creatures.
Somewhat surprisingly, the Giant Panda is incredibly well adapted to its environment, namely as a consequence of what I could only imagine to be a slightly monotonous diet of bamboo. One of the most evident of these adaptations is the ‘sixth toe’, actually an extension of the wrist bone of a Giant Panda. This gives the panda extra strength, which enables it to pull up shoots, pull off leaves and grasp bamboo. [1] This is crucial for a Giant Panda as 99% of their diet consists of bamboo shoots and leaves, [2] and thus being able to extract this plant easily is fundamental to their survival.

Pandas belong to the family of bears, the Urisdae family, and have a particularly well adapted jaw and head to again enable huge bamboo consumption, as it is a tough and firm plant. The jaw muscles of a Giant Panda need to be incredibly strong to chew such a plant (think of it as a human chewing toffee all day) and thus the cranial cavity of the giant panda has evolved to accommodate these larger jaw muscles [2], ensuring the survival of the Giant Panda as it allows for the vast consumption of bamboo, their main source of food.

Along a similar theme, the molars of a Giant Panda has evolved to be very large and frictionless, differing the Giant Panda again from the Urisdae family as it is a species which only uses its molars, whereas most other bears uses their canines to hunt and kill their food.

As eating is evidently what the Giant Panda is best adapted to do, the digestive system of a Giant Panda is also adapted to their favourite food, bamboo. The oesophagus of a Giant Panda has a tough lining to prevent tears, and the stomach is very strong and muscular as bamboo is a relatively hard food to digest, due to amount of cellulose it contains. For the same reason, unlike the rest of the Urisdae family the Giant Panda has a short intestine and a larger colon, as very little water is consumed by a panda each day and a very small amount of waste compared to the amount of food consumed.

Part of a Giant Panda’s undoubted charm is their slightly stocky appearance compared to most bears. Their legs have become more muscular and strengthened overtime, due to climbing trees for their average 20-40 pounds of bamboo a day [2]. As a result of this huge consumption of bamboo, Giant Pandas do not appear fragile, and actually weigh around 250 to 220 pounds [2] with their legs having to carry all this weight over long distances and up trees, for between 10-16 hours a day [2]. This is required to maintain the nutrition levels which are needed for the survival of pandas.

Consequently, while I can’t say my initial love of pandas came from their evolutionary features and not their ‘cute’ yet formidable appearance, it has certainly widened my interest and made them an even more fascinating creature – and yes, one I truly admire for their wholehearted commitment to bamboo.