Caffeine, Dehydration, and Joint Pain
A lot has been said about how caffeine dehydrates the body by promoting diuresis. But does this effect extend to the joints? Read on to find out.
Caffeine is a bitter, white crystalline alkaloid extracted from the leaves, seeds and fruits of certain plants including coffee seeds, tea leaves and kola nut.
This alkaloid acts as a pesticide in the plants producing it but a stimulant for the central nervous system in humans. Because of caffeine’s unique ability to temporarily prevent drowsiness and keep people alert, it has become the most popular, legal psychoactive drug in the world.
Therefore, caffeine is naturally found in or added to teas, coffee and drinks including cola, soft and energy drinks.
Regular intake of large amounts of caffeine can lead to a condition called caffeinism.
Caffeinism is characterized by sleep disturbance, irritability, headaches, palpitations, restlessness and caffeine dependence.
Caffeine intoxication is a more serious complication of ingesting large doses of caffeine. It is a toxicity reaction that causes restless, excitement, increased urination, rambling, mania, rapid heartbeat, disorientation, hallucination and psychosis.
Caffeine toxicity is not possible with coffee and caffeine drinks. It is usually caused by overdose of caffeine pills.
The unique pharmacological and chemical properties of caffeine are responsible for its remarkable effects on the central nervous system.
For example, caffeine is soluble in water and lipid, therefore, it can cross the blood-brain barrier and it is easily transported in the body. It is also structurally similar to adenosine, a nucleoside which is important to genetic materials such as DNA and RNA; a component of the energy-producing molecule, ATP; and a neurotransmitter in the brain.
Therefore, when caffeine crosses over to the brain, it inhibits adenosine receptors.
Long-term, moderate consumption of caffeine is safe and may even protect against certain diseases such as cancers and diabetes. However, caffeine is toxic at large doses. It also has a dependence potential and can cause sleep disturbance.
The most important effect of caffeine consumption is its diuretic property. By increasing the frequency of urination, caffeine encourages water loss which can be beneficial in improving edema but can also cause dehydration and rebound water retention.
However, the diuretic effect of caffeine is only significant in irregular consumers of caffeine products.
Regular users of caffeine usually develop tolerance to moderate caffeine doses and do not experience significant dehydration.
Joint pain is also commonly referred to as arthralgia. It can be caused by drugs, diseases, allergic reactions or injury.
Because the cartilage is the padding between bones at joints, it depends on a certain degree on moisture to maintain its integrity. Therefore, when the cartilage is dehydrated, it generates more friction which impedes its smooth sliding motion. This causes pain in the joints.
Furthermore, when the cartilage is dehydrated, it shrinks and begins to break down. These changes expose parts of the bone to not only rub against one another but to also press against nerves around the joint.
This causes local pain which can be sharp enough to discourage movement.
However, the link between general dehydration and cartilage dehydration is not well established. While the body can be dehydrated from increased water loss through diuresis, it will take a while before such effects will dehydrate the cells of the cartilage.
In fact, the only kind of dehydration that can produce this long-term effect is sub-clinical dehydration.
During sub-clinical dehydration, the body is not sufficiently dehydrated for a long time as to trigger the thirst reflex. In some people, especially the elderly, the thirst perception may not even be sharp enough to serve as a good indicator of the need for rehydration.
Some experts do believe that during sub-clinical dehydration, the body releases histamine. Histamine can trigger pain when it gets to the pain receptors.
Still, the theory that sub-clinical dehydration can cause joint pain has no scientific evidence. It is also unlikely that the level of dehydration that does not warrant the activation of the thirst center can cause joint pain.
Even if sub-clinical dehydration is a valid cause of joint pain through the release of histamine, there should be general pain all over the body instead of localized pain in the joints. This is because histamine release triggered by dehydration will have more extensive effects in the body.
A long-term longitudinal study investigating the effect of caffeine consumption on rheumatoid arthritis was published in the journal, Arthritis and Rheumatism in 2003. In this study, over 85,000 women were recruited and asked to complete food frequency questionnaires between 1980 and 1998.
The rate of diagnoses of rheumatoid arthritis was correlated with caffeine consumption in this group.
The analyses of the results of this study showed that caffeine does not increase the risk or symptoms of rheumatoid arthritis.
Furthermore, the result found out the consumption of tea, caffeinated coffee and decaffeinated coffee was not associated with increased incidence of rheumatoid arthritis.
The study summarized above was called the Nurses’ Health Study. It was a cohort study investigating the role of diet in a number of diseases. Therefore, it is a rich source of insight into the role of caffeine in the progression of arthritis diseases.
A second paper was taken out of this study and published in The American Journal of Clinical Nutrition in 2010.
This second paper also took the results of the long-term study to investigate the effects of coffee and caffeine on the incidence of gout in women.
With the diuretic property of caffeine, some people believed that caffeine may cause dehydration which is significant enough to trigger the crystallization of uric acid and the development of gout.
During the study period, only 0.01% of the participants were diagnosed with gout. This rather low percentage means that caffeine and coffee does not increase the risk of gout arthritis nor increase joint pain due to this form of arthritis.
In fact, the result of the study showed that long-term caffeine consumption is inversely related to the risk of gout. This means that caffeine can reduce the risk of gout (and by extension, joint pain due to gout) in women.
An earlier study published in the journal Arthritis and Rheumatism investigated the link between coffee (and its caffeine content) on the incidence of gout among men.
The 12-year study involved over 45,000 men who were assessed for gout every 4 years. At the end of the study, only 757 men had developed gout and the same inverse relationship between long-term coffee consumption and incidence of gout was observed.
Some have also put forward the theory that caffeine causes joint pain by interfering with some arthritis medications meant to reduce pain.
However, this is not often the case. Caffeine is a common ingredient in pain relievers. It is included exactly because it improves the ability of the primary active ingredient to reduce pain.
Experts estimate that caffeine makes pain relievers 40% more effective.
However, analgesics such as NSAIDs (non-steroidal anti-inflammatory drugs) like aspirin and ibuprofen that are also regularly prescribed to relieve arthritic pain. And their analgesic effects are improved by caffeine.
Most of these analgesics are formulated with caffeine to improve their effectiveness while reducing their doses and side effects. Therefore, caffeine improves rather than reduce their ability to provide relief for joint pain.
It is quite possible that caffeine may affect the efficacy of other arthritis medication but no such interaction has been successfully demonstrated in a clinical study.
The only such link in medical literature was an observation noted in a 2001 paper, presented at a meeting of the British Society for Rheumatology, which found that arthritis patients who were coffee drinkers were more likely to experience treatment failure with methotrexate than non-drinkers.
http://www.ncbi.nlm.nih.gov/pubmed/14613266 http://www.ncbi.nlm.nih.gov/pubmed/17530645 http://www.arthritistrust.us/Articles/Prevent%20Arthritis%20and%20Cure%20Back%20Pain.pdf http://www.health.harvard.edu/fhg/updates/update0206a.shtml http://onlinelibrary.wiley.com/doi/10.1002/art.10766/full
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