Spinach fights stress, inhibits stress hormone
Spinach reduces the harmful psychological and hormonal effects of chronic stress. Korean anti-aging researchers at Gyeongsang National University School of Medicine come to this conclusion in an animal study published in the Journal of Clinical Medicine.


The researchers imitated the effects of chronic psychological stress in animal experiments that lasted 15 days. The researchers put mice in a tube for two hours a day in which the test animals could not move [STR]. This is a significant stress stimulus for mice, which increases the release of stress hormone.Corticosterone plays the same role in mice as cortisol in humans.
Some of the mice were fed standard chow without additives [ND]. This was the control group. Other groups of mice were given spinach extracts. The Taiwanese experiments with freeze-dried spinach powder [FP], an alcohol extract of spinach [EE] and a water-based spinach extract [WE].
In this post, we will mainly focus on the effects of the freeze-dried spinach powder. They were the most interesting. Moreover, this powder is available as a superfood supplement. If the mice in the spinach powder group had been adult humans, they would have consumed 6-9 grams of spinach powder daily.
Spinach powder had no significant effect on body weight or food intake, but it did reduce the concentration of corticosterone in the mice's blood.

During the experiment, the researchers hung the mice on their tails for 6 minutes, and measured how long the animals dangled inactive [immobile duration]. When mice are depressed - in this case due to an excess of stress stimuli - they don't move and just hang. If not, they swing back and forth trying to escape.
You can see in the figure below left that spinach powder shortened the immobile duration.
CTL = mice that did not receive stress stimuli; STR = mice that the researchers had put in a tube.

In another experiment, the researchers determined whether the mice could appreciate sugar water [sucrose preference]. Depressed mice lose their sweet tooth, mentally healthy mice do not. You can see above that spinach also mitigated this aspect of depression.
In the medial prefrontal cortex of the mice, stress reduced the concentration of the amino acids glutamine [Glu] and glutamic acid [Gln]. Spinach extract prevented that. The researchers suspect that this effect explains the stress-reducing effect of spinach.

J Clin Med. 2018 Oct 31;7(11):406.