Wednesday, November 11, 2009

Chocolate & Stress

This is a sequel to one of my previous posts:

A recent study looked at various hormonal and metabolic changes associated with consuming chocolate. In this case, 30 people were given 40 g of dark chocolate daily for 2 weeks. The authors conclude that the chocolate consumption was responsible for reducing metabolic changes associated with stress, including cortisol and catecholamine excretion.

Weaknesses of the study include its brief, non-randomized, non-blinded nature (mind you, many of us would not easily be fooled by a placebo chocolate substitute!). And I see that the study is associated with the "Nestle Research Centre" in Switzerland. While I am pleased to know that a large chocolate company has a "research centre," I do have to wonder if there could be a higher risk of bias at play.

Here's a link to the abstract:

In the meantime, there is a variety of evidence out there that chocolate consumption in moderation is good for your health, in a variety of ways.

However, one concerning issue I just learned about has to do with lead contamination in cocoa and chocolate products. Lead is a heavy metal poison which should not have any presence in the diet. It can have widespread toxicity, particularly affecting the nervous system, through either acute or chronic exposure. The issue of lead in chocolate is discussed in mainstream research, such as by Rankin & Flegal (references:, Based on some of this research, it may be true that raw, unprocessed cocoa nibs have no significant lead contamination, rather the lead in some cocoa and chocolate products may be the result of industrial processing.

Hopefully, manufacturers can address this issue, so that we can be reassured about safety, and so that we can get on with the enjoyment of one of life's great pleasures, knowing that it, in moderation, may also be good for psychological and medical health.


Anonymous said...

thank you for all these wonderful entries. I enjoy visiting your blog and reading them. From the focus on more upbeat and fun stuff, to memory tests, to current issues like flu anxiety, to more serious things like trying to survive a terrible day, it's very comforting to come here, like visiting a kind and caring friend. Keep it up.

Anonymous said...

Just glanced over this article:

One immediate though I had war related the cortisol aspect--

1) This study show a decrease in cortisol (or at least it's metabolites). Even if we assume that metabolites correlate with the amount in the blood steam... eating chocolate cannot really be applied to some patients with various forms of mental illness due to the HYPAC system malfunctions (hypothalamic-pituitary-adrenocortical axis)

You would need patients to undergo a dexamethasone suppression tests first to see if they would even be responsive to decreases in cortisol and it's subsequent stress reducing aspects.

2) I am also surprised you didn't mention the amount of refine white/simple sugar used in chocolate products (not cocoa alone). Or the high saturated fat content... etc.

I am not suggestion to ban chocolate but just agreeing with your moderation idea.

3) A neat alternative to /cocoa is carob. But I don't think it has the same positive effects. (I will have to check on that.)


GK said...

Primary major endocrine disease leading to hypercortisolemia and consequent psychiatric disease can occur, but is quite rare, and would present with obvious physical symptoms and signs.

A more thorough assessment of endocrine function, e.g. via dexamethasone suppression tests, has little clinical relevance in psychiatry, despite theoretical interest, and its enthusiastic study in past decades.

It is true, though, that chronic stress states of most any kind may commonly lead to "subclinical" hypercortisolemia. The medical approach to this is not to treat the patients with cortisol-blocking agents, but to treat the underlying causes of the stress, whether they be environmental and/or psychological.

This study really is excessively simplistic in design and evaluation, despite the very fancy machines and analysis used. Yet it does show a correlation between trait anxiety and some levels of metabolites in serum and urine samples. And it shows that consuming chocolate daily for 2 weeks reduces the difference in these metabolite levels.

It is a further stretch to assume that chocolate is therefore a treatment for stress! And so, in part, I think this post is meant to be at least in part a light-hearted, half-serious piece of affirmation that moderate chocolate consumption is actually good for stress management.

There is, however, other fairly convincing evidence of health benefits from chocolate, including in the treatment of hypertension.