Coping with stress while the stress is going on can be hard enough. But did you know that a period of intense stress can actually change your brain in ways that stick around after the stress is gone? Sometimes it can even show up as irritable bowel syndrome or other health problems that don't seem connected to the stress at all.
The classic example is childhood stress (think: growing up really poor, being bullied in school, your parents having an awful divorce...). It's well-documented that early-life stress has long-term consequences, including dysregulation of the stress response later in life (flattened cortisol profile) and chronic inflammation that increases the risk of metabolic problems, hypertension, obesity, mood problems, and other negative health effects.
But kids aren’t the only ones at risk. This study suggested that long-term stress or insecurity at any age could be enough. As this study notes, chronic social isolation can also have a lot of similar effects. Another extreme of this is PTSD, which is also associated with a higher risk of diabetes, inflammation, metabolic problems, and hypertension.
Stress has these long-term aftereffects because the human stress response can “learn” about the world and adapt accordingly. Is the world a big scary stressful place that requires stress hormone levels turned up to 11 all the time? Your hypothalamic-pituitary axis (HPA for short) will adapt to that by pumping out more cortisol and other stress hormones all the time. That high stress response stays ingrained in your hormone regulation system even after the actual cause of the stress is gone. A constant flood of stress hormones also damages neurons in several brain areas, especially one called the hippocampus. Damage to these brain areas impairs stress hormone regulation, so stress hormone production and hippocampal damage turns into a vicious cycle.
But here’s the good news: the human brain and stress response aren’t set in stone. If they can “learn” to be hyper-stressed, they can also unlearn it. Even though growth of most neuron types stops when you’re young, the growth of neurons in the hippocampus keeps going even in adults. So there's always time to heal the damage.
Getting away from the stress stops the damage from getting worse, but it’s not always enough for true healing. So here four Paleo strategies for identifying and addressing this kind of "stress hangover." Since high stress hormones and damage to the hippocampus reinforce each other, diet strategies that affect either area can be helpful on the whole.
1. Know that the Problem Doesn’t Always Look Like "Stress."
You might think it would be easy to spot the unresolved after-effects of stress. They feel like being stressed out, right?
Sometimes, but not always. Under stress, neurons in the hippocampus and the prefrontal cortex (memory, executive function, and attention) get smaller, while neurons in the amygdala (anxiety, fear, and aggression) get bigger. This can cause problems with attention, mood, and memory even after the stress is gone. These problems are caused by stress, but they don’t necessary feel like "still being stressed out."
Also, as this review points out, many apparently inexplicable chronic conditions might actually be the aftereffects of stress. Examples include chronic fatigue syndrome, irritable bowel syndrome, and other similar conditions where there's no obvious physical cause of the symptoms. It’s common for these problems to be triggered by a very stressful episode in someone’s life and then not go away because the person still has long-term dysregulation of stress hormones, which affect pain perception, digestion, and brain function.
This doesn't prove that all cases of IBS or fatigue are caused by stress. But if this story sounds familiar, it might be worth checking out.
2. Consider Omega 3-6 Balance
There’s some evidence that the ratio of Omega-3 to Omega-6 polyunsaturated fats in the diet can help recovery from long-term stress damage.
Rats stressed early in life do worse on a a diet deficient in Omega-3 fats. This might be caused by the way Omega-3 fats affect the hippocampus: they improve hippocampal function, counteracting the damage of chronic stress in the brain. This basically breaks into the stress -> hippocampus dysfunction -> more stress cycle.
These studies suggest that people struggling with the aftereffects of stress might do well to take care of their Omega-3s: think fish, seafood, and even plant sources.
3. Eat Antioxidants (Especially if you also Eat High-Fat)
Related to the problem of inflammation and Omega-6 fats, there’s the issue of antioxidants. There’s quite a bit of evidence that antioxidants can help heal the lasting effects of stress, but first we have to take a detour into the notorious high-fat diet (HFD).
If you do any independent research on this topic, you’ll find tons of HFD rat studies. And in almost every case, the HFD causes the poor rats no end of problems. It prevents stress recovery or even makes things worse than they originally were. And that looks really bad for Paleo eaters – it looks like it completely contradicts the line that fat is good for you.
But! Several studies suggest that the problem isn’t really fat, but inflammatory oxidized fat, which is something Paleo has always been concerned about. Most HFDs in rat studies have pretty awful fat quality, which means that the fats are vulnerable to oxidative damage. Antioxidants protect against oxidative damage. When researchers give rats vitamin E, which is a powerful antioxidant, all the problems of the HFD mysteriously vanish. In fact, Vitamin E seems to be even more effective than vitamin C, another antioxidant.
This review notes that a variety of different polyphenols (plant antioxidants) have beneficial effects on hippocampal volume and function in stressed humans.
Taken together, these studies are encouraging for high-fat diets…if you also eat your vegetables, spices, and/or other antioxidant-rich foods (like coffee and tea). Antioxidants are probably good for restoring or maintaining neurons in the hippocampus. That breaks into the cycle of hippocampal damage -> hormone dysregulation -> hippocampal damage and helps with healing.
4. Go for a Walk
Exercise is a powerful way to improve brain function in the hippocampus, mostly by increasing levels of brain-derived neurotrophic factor (BDNF).
This study found that rats exposed to early-life stress did better as adults if they engaged in voluntary exercise. In moderate doses, exercise helps regulate stress hormones. It also increases the growth of neurons in the hippocampus, repairing the damage caused by cortisol overload. There’s plenty of evidence that exercise improves hippocampal function by releasing BDNF in humans, which suggests that the animal results translate well.
Oh, and some more evidence that you shouldn’t worry about a healthy high-fat diet: just like antioxidants, exercise prevents HFD-induced brain problems. Again, it’s starting to look like a high-fat diet is only dangerous if it’s a typical American style high-fat + high-sugar junk food diet accompanied by a totally sedentary lifestyle.
Of course, this always comes with a caveat: too much exercise can be a source of chronic stress. But in moderate doses, exercise can be a very powerful healing tool.
5. Keep an Eye on Blood Sugar Regulation and (Maybe) Try Keto
Considering the role of insulin in the brain and the importance of blood sugar control in diseases like Alzheimer’s disease, a plan for blood sugar regulation is probably a good idea for anyone trying to heal from stress damage. This review gives a good look at how insulin resistance and metabolic problems can increase stress hormone production, which causes more insulin resistance, etc. Addressing insulin through diet is one way to break that vicious cycle and start healing from the longer-lasting effects of high stress exposure.
And then there’s a ketogenic diet (confused? Read more here). Keto isn’t for everyone, but there’s some interesting evidence that it might be helpful to the hippocampus. For example, in this study, a ketogenic diet increased antioxidant levels in the hippocampus and protected hippocampal cells from neuron damage in rats. (This is even one more piece of evidence that fat doesn’t damage your brain – if that were at all true, how could keto be protective?).
A Useful Plan for the Real World
In the real world, most people have probably experienced at least one relatively long period of high stress. This isn't exactly a rare or unheard-of problem. Simply removing the source of the stress doesn’t always fix the problem if your hippocampus and stress hormone regulation systems are already trained to follow high-alert freakout patterns. Even after the actual stress is over, the long-term effects may include everything from mood changes to chronic digestive problems to a higher risk of weight gain later in life.
There hasn’t been a huge amount of research on diet and stress healing, but the points above – Omega-3 fats, exercise, antioxidants, blood sugar control, possibly ketosis if it works for you – are a decent place to start.