Paprika protects against Parkinson's
It might be that people who eat lots of paprika or peppers are dramatically reducing their chance of developing Parkinson's disease. This is suggested by an epidemiological study that researchers at the University of Washington published in the Annals of Neurology. Paprika and peppers, but tomatoes too, contain nicotine, capsaicin and other substances that protect brain cells.
In the first stages of Parkinson's, brain cells that produce dopamine die off. As a result, people with Parkinson's find movement increasingly difficult; their muscles start to stiffen and become painful, their enjoyment of life decreases and they lose their ability to make decisions.
Smoking and passive smoking protect against Parkinson's and this is probably because tobacco smoke contains nicotine [structural formula at right]. [Mov Disord. 2012 Jul;27(8):947-57.] That's not to say that smoking is 'therefore' healthy: the chance that if you smoke you won't get Parkinson's is pretty remote, but the chance that you'll die of lung cancer if you smoke is pretty high.
Plants in the nightshade family – potatoes, aubergines, tomatoes, paprika and peppers – also contain 2-7 mcg nicotine per kg. A normal diet easily provides more than 1 mcg nicotine per day, and several percent of the population consume more than 2 mcg nicotine per day. [J Agric Food Chem. 1999 Aug;47(8):3113-20.] To give you an idea: if you sit for three hours in a room filled with tobacco smoke, you'll consume 1 mcg nicotine. [N Engl J Med. 1993 Aug 5;329(6):437.]
The researchers were curious whether people who consumed large amounts of nightshade family plants were less likely to develop Parkinson's, so they compared the eating patterns of 490 people who had just been diagnosed as having Parkinson's with those of a control group.
The researchers discovered that green, yellow and red paprika and peppers protected against Parkinson's. Tomatoes protect too, but less so; potatoes and aubergines have no protective effect.
People who eat paprika or peppers daily halve their chance of developing Parkinson's compared with people who never eat these vegetables. The protective effect of paprika and peppers is greatest if you don't smoke.
Not only nicotine
The researchers believe that the protective effect of paprika and peppers is not just due to nicotine. Paprika also contains the nicotine analogue anatabine [structural formula at right]. Animal studies have shown that anatabine inhibits Alzheimer's, and who knows, maybe anatabine has the same effect on Parkinson's. [Eur J Pharmacol. 2011 Nov 30;670(2-3):384-91.]
Another group of substances found in paprika and pepper are the capsaicin analogues. The structural formula of capsaicin is shown here. These substances stimulate the TRPV1 receptor. According to some studies, high concentrations of capsaicin can damage brain cells via the receptor, but other animal studies suggest that capsaicin actually protects dopamine-producing brain cells. [Brain Res Bull. 2012 Nov 1;89(3-4):92-6.]
Ergonauts who are contemplating experimenting with these findings are perhaps best to confine themselves to vegetables rather than trying high-dose supplements.
"Epidemiological studies may shed further light on our somewhat novel hypothesis and findings", the researchers conclude. "Although they are consistent with the well-established inverse association between Parkinson's disease and tobacco use, it remains unknown whether nicotine reduces Parkinson's disease risk and whether TRPV1 agonists, including those in peppers, are neuroprotective or neurotoxic."
"Replication of our findings will be needed to strengthen causal inferences that might eventually lead to dietary or pharmaceutical interventions designed to help prevent Parkinson's disease."
Ann Neurol. 2013 Sep;74(3):472-7.
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