Chocolate. It’s sweet, it’s tasty, we desire it and crave it. It is a food that brings immense pleasure and enjoyment. And in case you were looking for any more valid reasons to eat it, scientific research now confirms that it can be good for you. In today’s podcast, you’ll learn about the heart, exercise and brain health benefits of chocolate.
The history of chocolate dates back thousands of years. Chocolate is made from cocoa beans which grow on Cacao trees. The cocoa bean is roasted and ground to make cocoa liquor which has a fat content of about 50 percent in the form of cocoa butter. The cocoa butter can be removed which leaves behind the solid cocoa powder.
Milk chocolate has milk and sugar added to a blend of cocoa powder and cocoa butter, but has less cocoa content than dark chocolate. Dark chocolate has typically 2 to 3 times more cocoa than milk chocolate which is why it is so ‘dark’, but doesn’t contain any milk solids and typically has less sugar added than milk chocolate. The cocoa content of dark chocolate can range from 30 percent up to well into the 90 percent range if you like that level of bitterness. Then there is white chocolate, and as tasty and sweet as it is isn’t really ‘chocolate’ as it only uses cocoa butter, a lot of sugar and contains no cocoa powder.
While chocolate is a good source of protein, magnesium, calcium and potassium and some vitamins such as riboflavin and vitamin E, these are nutrients we can easily get from other foods. It is really dark chocolate that is the star of the show when we’re looking at health benefits. Dark chocolate is a rich source of flavanols, in particular substances called catechin and epicatechin, which are potent antioxidants and which can also have favourable effects on the heart and blood vessels. It is the cocoa content of chocolate that is the source of these flavanols so dark chocolate will contain much more flavanols than milk chocolate. Apples, grapes, red wine and tea are also rich sources of these flavanols.
Dark chocolate has been shown to lower blood pressure, decrease oxidation of the more harmful LDL-cholesterol, improve blood flow by causing relaxation of the muscles lining blood vessel walls, and improve the action of insulin. Longer-term, there is some evidence that people who are regular eaters of cocoa-containing foods have lower rates of cardiovascular disease. Yes, chocolate can be healthy for you.
Because compounds in dark chocolate appear to be highly protective against the oxidation of LDL, this could translate into much less cholesterol lodging in the arteries, resulting in a lower risk of heart disease. Oxidised LDL means that the LDL-cholesterol has reacted with free radicals. This makes the LDL particle itself reactive and capable of damaging other tissues, such as the lining of the arteries in your heart. Cocoa contains an abundance of powerful antioxidants that do make it into the bloodstream and protect lipoproteins like LDL against oxidative damage. Dark chocolate can also reduce insulin resistance, which is another common risk factor for many diseases like heart disease and diabetes
In fact, several long-term observational studies indeed show the benefit of regular chocolate consumption with a 2019 meta-analysis involving 23 studies and over 400,000 participants finding lower rates of heart failure, stroke, heart attack and coronary heart disease in regular eaters of chocolate with benefits seen with up to 100 grams of chocolate per week. And I’ll link to the study in the show notes. https://pubmed.ncbi.nlm.nih.gov/30061161/
Of course, observational studies can’t prove that it was the chocolate that reduced the risk here, but since the known mechanism of lower blood pressure and less oxidised LDL is known to happen with chocolate-eating, it is plausible that regularly eating dark chocolate may reduce the risk of heart disease.
A healthy serving of dark chocolate is considered 25 grams two to three times a week. For heart-health benefits from eating dark chocolate, even one square of chocolate a day can give some benefit. With chocolate, the best advice is to always go for quality over quantity and include some dark chocolate for variety. But not all dark chocolate is equal. The benefits come from the cocoa, and many ‘dark’ chocolates don’t contain enough flavanols to give you any real effect. To get the benefits, stick to the bitter, darker varieties, with a cocoa solids content of 70 per cent or higher.
Exercise
But could chocolate have additional health benefits apart from on the heart? Far from being just an antioxidant, flavanols can improve blood flow, reduce oxygen cost, improve insulin sensitivity and improve immune responsiveness. It helps achieve this through increased bioavailability and bioactivity of nitric oxide. The potential benefits from flavanols on nitric oxide production tick many of the boxes that athletes are looking for in improving performance.
Most of the research on dark chocolate has looked at the cardiovascular health in people with pre-existing medical conditions. There has only been a limited focus put on exercise performance in a healthier sporty population.
Putting dark chocolate to the exercise supplement test, 9 moderately-trained male participants volunteered to undertake a series of baseline tests looking at their maximal oxygen uptake (VO2max), lung gas exchange measures, and 2-minute exercise bike time trial performance. They performed each trial two weeks apart under conditions of either consuming daily 40 grams of dark or white chocolate (which contains no polyphenols) leading up to the trial. And I’ll link to the study in the show notes http://jissn.biomedcentral.com/articles/10.1186/s12970-015-0106-7
Dark chocolate consumption improved time trial performance relative to both the baseline conditions and white chocolate consumption conditions. This equated to a 17 percent greater distance covered when eating dark chocolate compared to the start of the experiment. And 13 percent more distance was covered compared to eating white chocolate.
There was also a significant 6 percent improvement in VO2max under the dark chocolate conditions compared to baseline conditions. The same 6 percent improvement was also seen when dark chocolate was eaten compared to white chocolate, but this didn’t reach the level of statistical significance. There were no statistical differences in blood lactate, heart rate, or blood pressure between the different experimental conditions, but dark chocolate showed a trend for improving many of these measures.
Keep in mind with this study that the taste of dark chocolate is quite distinct, so it was not possible to blind the participants to what they were eating. So, some placebo effect could have played a role if participants expected the dark chocolate to have a benefit.
This was only a small study. But as far as proof of concept goes, it certainly gives a green light to more research in this area. When you put in context that all that is being used is a small amount of dark chocolate, then there appears little harm in athletes jumping the gun early and trialling it for themselves.
Brain
And there is the role that chocolate could play in our brain. The chemicals found in chocolate promote the release of the feel-good hormone serotonin, which may be one reason to explain its desirability. Many people report cravings for chocolate, and far from being a true drug effect, actually come from its unique smell, taste and texture which few other foods have. Your chocolate craving is real.
In fact, a recent randomised controlled trial published only 2 weeks ago showed that people eating a high polyphenol diet that included 50 grams of 70 percent dark chocolate each day for 4 weeks showed fewer symptoms of depression and improved mental health compared to when they weren’t eating the chocolate. And I’ll link to the study in the show notes https://www.mdpi.com/2072-6643/12/8/2445/htm
And no, this study wasn’t funded by the chocolate industry even though they used ‘off the shelf’ Lindt chocolate. But, a lot of chocolate research has been sponsored by industry. This in no way means the results are fraudulent or not to be trusted, but industry sponsored research is far more likely to show a favourable result in published studies because firstly industry is more likely to fund research that has a good chance of giving a positive finding and secondly, some researchers may be disallowed from publishing research that gives a negative finding. It is possible that other flavanol-containing foods could be just as potent, if not more, than chocolate, but the research dollars may just not be there to drive this research if we are talking about humble fruit and vegetable growers. Although what would you rather read more in newspaper headlines: ‘Scientists discover chocolate is healthy for you’ or ‘Scientists discover cabbage is good for you’? I rest my case.
There is a lot of interest into how flavanols can help the brain work. As we age, the body does not perform as well as it did in our youth. Declining brain function, which is termed cognitive impairment, is probably the most concerning health problem facing an ageing population. Having regular ‘senior moments’ of forgetfulness is the first stage of mild cognitive impairment which if it progresses, can lead to dementia. So now researchers are looking at how chocolate may give a brain boost in people with failing brain function.
Randomly assigned to consume one of three different hot chocolate cocoa beverages containing either low, medium, or high amounts of flavanols, 90 people with mild cognitive impairment took part in an 8-week study. And I’ll link to the study in the show notes https://pubmed.ncbi.nlm.nih.gov/22892813/
A battery of four different validated and robust measures of mental performance were undertaken over the study. Three of the cognitive tests showed a statistically significant improvement in mental performance with higher amounts of flavanols consumed and the fourth test was heading in the right direction. Validating the known metabolic actions of flavanols, improvements were seen in insulin resistance, blood pressure, and lipid oxidation in people in the high and medium flavanol consumption groups. All three of these metabolic factors are linked to the risk of dementia.
Boosting flavanol consumption could be a tasty and effective way of managing cognitive decline with age. While we wait for larger types of studies carried out for longer periods to be published, enjoying a cup of hot chocolate and other rich flavanol-containing foods may make the waiting worthwhile.
Be kind to your dog
Just a word of warning to dog lovers here. Chocolate contains the natural chemical theobromine which is a stimulant found in the cocoa bean. Theobromine (along with the caffeine) increases urination and affects the central nervous system as well as heart muscle. Theobromine poses no real health issues for us humans (and even if it did, it’s doubtful people would stop eating chocolate!), but for dogs, it’s potentially poisonous and can trigger vomiting, nausea, increased urination and diarrhoea. So, keep chocolate away from your dog.
Chocolate is a food that brings immense pleasure and enjoyment and certainly can be a part of any person’s diet. While true health benefits likely only lie in the dark variety of chocolate (and here, go for quality dark chocolate with 70 percent or higher cocoa content), the ‘active ingredient’ in dark chocolate can equally be found in fruit, vegetables and tea so think of dark chocolate as something to add to a healthy diet, not be the central theme of.
So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on if it supports it, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.
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I’m Tim Crowe and you’ve been listening to Thinking Nutrition.