Carotenoids are found in plant based foods, most of which are orange and red in colour such as carrots, sweet potatoes, squash, peppers, tomatoes, apricots, mango as well as green leafy vegetables. Carotenoid is a phytonutrient (antioxidant) and can be converted by the body into vitamin A. Carotenoids are divided into two groups – carotenes and xanthophylls, these are then sub categorised further into 9 groups including alpha and beta carotene, lycopene, beta cryptoxanthin, lutein and zeaxanthin. Lycopene is the carotenoid in tomatoes that gives them their cancer fighting reputation.
Carotenoid is of interest to scientist looking at Parkinson’s due to vitamin A’s role in gene expression but more so because of carotenoid’s antioxidant qualities. In mice beta-carotene has been shown to protect against MPTP. MPTP is a protein which forms in the brain and increases permeability of mitochondria leading to neuron cell death, as happens in Parkinson’s. Lycopene has been proven to reduce oxidative stress and cognitive decline in rodent models of Parkinson’s. However similar tests in primates have not shown the same response and these tests have not been conducted on humans. Looking for evidence of the benefits of carotenoids in humans we turn to epidemiology studies. K.C.Hughes and colleagues in 2014 reviewed the research to date. They found that numerous studies have shown an inverse relationship between alpha- carotene and beta- carotene intake and risk of Parkinson’s (high intake and lower risk) and one looking at Zeaxanthin, however for some the difference was not significant. Other studies looking at lycopene, beta cryptoxanthin and lutein have provided very mixed results with some studies even showing a positive relationship. Analysing the pooled results Hughes et al advised that it was not possible to draw definitive conclusions on the role of carotenoids on Parkinson’s. The full report can be read at
As with so much research into Parkinson’s there is no definitive answer. Parkinsons.me are covering this subject to highlight the potential benefits of carotenoids but also the thinness of evidence. Research into carotenoids and Parkinson’s continues and hopefully in the future there will be clearer results.