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Chocolate: a feel good friend?

By Laura Hooper

Photo credit: Pixabay

With Easter firmly behind us, I’m sure that we have all over indulged in an Easter egg or two, savouring that chocolately gold and the good feelings it brings (before the potential guilt, that is!). But why is chocolate associated with feeling good? And why do so many of us crave it, especially during periods of sadness or stress?

Chocolate, and its effects on the human body have been a topic of research for a long time, and many differing opinions have been long debated over. Michael Macht and Dorothy Dettmer conducted one such experiment into the effects of chocolate on our mood. This involved studying the effects of chocolate on the emotions of 37 female college students in Germany. The students completed a survey rating their emotions, for example hunger, guilt, or joy before eating on a scale of 0-7. An overall mood rating was also recorded, ranging from 0 (very bad) to 10 (very good). Students then ate an apple, chocolate bar, or nothing and the survey was completed again at 4 different time intervals after eating (or not eating), to see how their mood had been affected. This was done twice a day for 6 days and participants were not allowed to eat for an hour before the first survey.

Results showed that after consuming chocolate, mood was more strongly elevated, and remained at a higher level than those who ate either an apple or nothing. It is possible that the elevation in mood between 60 and 90 minutes was due to knowledge that the participants would soon be able to eat again.[1]

In my opinion, this study appears to have some limitations, such as the use of only female participants of a potentially similar age. In addition, a greater selection of food to test against the chocolate would have provided more data and depth to the study, as an apple is at the other end of the food spectrum to chocolate! However, it does imply that eating chocolate does indeed cause the elevation in mood that so many of us have experienced. But why is this?

Photo credit: http://scienceblogs.com/cognitivedaily/2006/10/11/chocolate-really-does-make-us/

Firstly, chocolate contains fat and carbohydrates, in the form of sugar, which gives us a boost of energy. Also, the carbohydrates in the chocolate signal to the body to produce more serotonin, a chemical associated with happiness (as explained in detail later in the article). Small protein-like molecules called endorphins are also released when you eat chocolate, and these act as natural painkillers and result in feelings of euphoria. As well as this, we all know that chocolate contains caffeine, which is a stimulant for our body, acting as a sugary pick-me-up [2].

I mentioned that when we eat chocolate more serotonin is produced. Chocolate not only stimulates serotonin production and release upon consumption, but it also contains an amino acid that the brain needs to make serotonin [3]. This amino acid is called tryptophan, and it is known as an ‘essential amino acid’ as humans cannot make it, so we have to get it from our diet in foods such as chocolate, milk, fish and oats [4]. Tryptophan was first reported and isolated in 1901 by Frederick Hopkins, and is a very important amino acid used in protein synthesis, as well as being a precursor for serotonin. The enzyme tryptophan hydroxylase is responsible for modifying the tryptophan into 5-Hydroxytryptophan during serotonin synthesis [4].

So we know that chocolate results in a rise in serotonin production upon consumption, and contains a precursor for the future synthesis of it, but what does serotonin do? It was isolated in 1948 by Maurice M. Rapport, and is mostly found in the gastrointestinal tract, brain and blood platelets. Serotonin is a neurotransmitter, and this means that it acts as a signal molecule between nerves [5]. The space between the neurons is called the synaptic cleft, and it is across this that neurotransmitters, like serotonin, diffuse to carry signals from one nerve to another to cause an effect [6]. The presynaptic cell is where the serotonin is made from its precursors (tryptophan), and stored in synaptic vesicles. Once a signal is received in the presynaptic cell e.g. from eating chocolate, the vesicles containing serotonin will fuse with the pre-synaptic membrane and serotonin is released into the cleft via a process called exocytosis. Serotonin will then diffuse across the cleft to the postsynaptic cell where it will bind to specific serotonin receptors thus eliciting its effects [6].

Chocolate can impact our bodies in many ways not just by lifting our mood. Research suggests that it may also have a positive influence on heart health. It is important to note that the following possible benefits for cardiovascular health come from eating dark chocolate with a high cocoa content as opposed to milk chocolate. Plants contain molecules called flavonoids that have antioxidant properties and also help to protect the plant from toxins and repair damage. Interestingly, these flavonoids are also present in dark chocolate [7]. The antioxidant properties of these flavonoids help the body to prevent damage to cells caused by free radicals (molecules formed by normal processes such as breathing, but can cause cellular damage if they aren’t removed). Cocoa beans in chocolate contain flavanols (a type of flavonoid), which as well as acting as an antioxidant, can also improve health. For example they can contribute to a reduced blood pressure by resulting in the widening of blood vessels, so improving blood flow to vital organs such as the heart and brain. They could also reduce the stickiness of blood platelets thus reducing the risk of blood clotting [7].

So it appears that chocolate can have multiple benefits for us, from improving our mood to influencing our general health. Of course all potential benefits are increased with the cocoa content of the chocolate, therefore although milk chocolate can boost our mood, it would have a lesser effect than a high quality dark chocolate. In addition, research and findings on the possible benefits of chocolate are highly disputed in the scientific community, thus more research is required in order to clarify and confirm them. Don’t forget also that alongside potential good effects, chocolate can have negative impacts such as weight gain and problems associated with the high sugar content such as tooth decay. So remember, do enjoy your chocolatey treats in moderation!


References

  1. [1]M.Macht et al., Appetite, 2006,46,332-336
  2. [2]All about chocolate, available from https://kkloukin.web.cern.ch/kkloukin/chocolate.htm,[accessed 16/03/16]
  3. [3]Chocolate:good for the mind, body and spirit, Medical Wellness Association, available from http://www.medicalwellnessassociation.com/articles/chocolate_benefits.htm , [accessed 18/03/16]
  4. [4]Tryptophan, Medical Encyclopedia, available from https://www.nlm.nih.gov/medlineplus/ency/article/002332.htm, [accessed on 18/03/16]
  5. [5]Serotonin: Facts, what does serotonin do?, available from http://www.medicalnewstoday.com/articles/232248.php, [accessed on 14/03/16]
  6. [6]B Alberts et al., “Molecular Biology of the Cell”, 5th ed, 2008, 682-683, Garland Science, Taylor and Francis Group
  7. [7]Heart Health Benefits of Chocolate, available from http://my.clevelandclinic.org/services/heart/prevention/nutrition/food-choices/benefits-of-chocolate,[accessed 18/03/16]

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