听
Just about every day we are confronted with some report about some food that is going to extend our life or accelerate our demise. Sometimes it鈥檚 even the same food! One day we are urged to use vegetable oils instead of animal fats, and the next day may bring a study informing us that soybean oil is linked with obesity. Coffee is a villain one day, a hero the next. Ditto for eggs, red wine or dairy Worried about depression? A study tells us that individuals with the highest consumption of ultra processed foods have a significantly higher risk of depression. But if you want to treat depression, reach for watermelon and tomatoes. Most of these studies are of academic interest and have little practical importance. As an example, let鈥檚 delve into whether watermelon and tomatoes can really help with depression.
听鈥淧igment in tomatoes and watermelon could help cure depression-but there鈥檚 a catch鈥� screamed a headline in the New York Post. There sure is a catch, and it鈥檚 a pretty big one. The article in question was spawned by a study in the journal 鈥淔ood Science & Nutrition鈥� by scientists at the Chongqing Medical University in China. Tomatoes or watermelon were not involved, neither were people. The study was all about male mice that were stressed by being placed in a cage with other mice that had been bred to be aggressive. Half the stressed mice had lycopene, the pigment found in tomatoes and watermelon, piped into their stomach every day, and half were similarly treated with placebo. The researchers then looked at changes in the mice鈥檚 behaviour such as extent of struggling when hung upside down by the tail as well as their preference for drinking sugar sweetened water. They also looked for changes in 鈥渟ynaptic plasticity鈥� in the hippocampus of the lycopene treated and untreated mice.
Synapses are the junctions where nerve cells (neurons) communicate with each other or with other cells, like muscle cells. The communication is via chemicals called neurotransmitters that are released by one nerve cell, cross the tiny gap called the synaptic cleft that separates cells, and then fit into proteins termed 鈥渞eceptors鈥� on the receiving cell. 鈥淪ynaptic plasticity鈥� refers to changes that occur at the synapse, either strengthening or weakening the synaptic connections. The hippocampus is a brain structure that controls many body functions including emotions and behaviour and its performance is dependent on the connections between the nerve cells it harbours, that is, its synaptic plasticity.
At the end of the experiment, the mice were 鈥渟acrificed鈥� and their brains examined under the microscope. The hippocampus was also analyzed for a number of synaptic proteins. They found that stress had induced pathological changes in the hippocampus, but less so in the lycopene treated mice. Also, the proteins present in the hippocampus of the treated mice were associated with less synaptic dysfunction, and such dysfunction is believed to be associated with depression. 鈥淏elieved to be鈥� is not exactly hard science.
As far as behaviour goes, stressed mice are less keen to drink sweetened water and struggle less when hung upside down. Both of these are said to be signs of depression. The stressed but lycopene treated mice struggled for a longer time and were more eager to drink the sweetened water and this was interpreted as being less depressed. Somewhat of a stretch to relate this to human behaviour.
And then there is the big 鈥渃atch.鈥� The dose of lycopene used in the mouse experiment was the equivalent of 150 mg of lycopene daily for an adult human. That amount would be found in 21 tomatoes or 14 cups of watermelon. No studies have ever used that much lycopene in people, so it is not possible to say whether it is safe. Another headline reporting on the Chinese study wondered 鈥淐an eating tomatoes, watermelons cure depression?鈥� My answer would be 鈥渘ope.鈥� And as far as that study about ultra processed foods causing depression goes, well I see no need to dig into it. There are many excellent reasons to stay away from ultra processed foods without worrying about whether or not they cause depression. Something that can cause depression is being accosted by meaningless nutritional studies every day.
