Dark chocolate – health benefitsPawel Malczewski
- Dark chocolate is nutritious and rich in powerful health promoting polyphenols
- The healthiest dark chocolates are the least processed ones, with the highest proportion of non-fat cocoa solids and the lowest amount of sugar.
- Eating high cocoa dark chocolate may decrease the risk of cardiovascular disease. Regular consumption helps to reduce inflammation, increase vasodilation, improve BP, inhibit platelet adhesion and improve lipid profile.
- It is associated with potential benefits in infectious diseases and cancer, type 2 diabetes, central nervous system and skin protection.
In this article
- What is dark chocolate?
- What makes dark chocolate healthy?
- Health benefits of dark chocolate
- Negative health effects of eating dark chocolate
What is dark chocolate?
Dark chocolate is a solid product made of roasted cocoa bean mass cocoa liquor, with or without the addition of extra cocoa butter and with or without some form of sweetener (whether sugar or artificially based).
These are the bases that define dark chocolate. However, additional labelling laws can be applied, for instance:
In the U.S., the law states that the dark chocolate (semisweet/bittersweet) contents must be chocolate liquor >= 35% and milk solids < 12%. (read more..)
There are two different components in cocoa:
- Non-fat cocoa solids
These contain high antioxidant activity and are rich in polyphenols, fiber and some minerals. Most health benefits of dark chocolate are derived from these elements.
- Cocoa butter
It contains a high amount of fatty acids and relatively (in comparison to non-fat cocoa solids) small amounts of antioxidants. Cocoa butter has a neutral effect on health.
A few facts about dark chocolate products:
- Cocoa and cacao means the same, although recently “cacao” has been popular within raw vegan circles to describe an unroasted cocoa/cacao products. (read more..)
- Some show the “Cocoa %” or “Cocoa solids %” on their labels, as in the image below.
This percentage indicates how much of the total non-fat cocoa solids and cocoa butter is contained in the chocolate. However, the specific proportions of the non-fat and the fat components are not disclosed to consumers, since they are considered to be a part of the secret recipe.
- Generally, the higher the cocoa percentage is, the more bitter, harder and less palatable the chocolate tastes. The bitter taste comes from the health promoting flavonols.
- Extra cocoa butter is usually added to dark chocolate to make it smoother and less bitter.
What makes dark chocolate healthy?
- The higher the non-fat cocoa solids component of the “cocoa %”, the healthier the product. (1)Available here.
- “Cocoa%” is a good but not completely reliable indicator of the polyphenol contents of dark chocolate. For instance, some chocolates of 85% cocoa may have less polyphenols than 70% cocoa chocolates (see below).
- Roasting cocoa beans can reduce the antioxidant activity of flavonoids by more than 10 times in comparison to natural cocoa, and this reduction increases with the roasting time. (2)Available here., (3)Available here..
- Roasting cocoa beans also increases the content of melanoidins. These are a type of Maillard reaction product that are formed during the roasting process, which partially replace other antioxidants (4)Available here.
- Alkalizing (Dutching) of cocoa is used to neutralize the acidity of the chocolate and the bitter taste of flavonoids. This significantly reduces the flavonol content in cocoa. Heavily alkalized chocolate can have up to 5 times less flavonols than natural cocoa (although those amounts are still higher than low cocoa chocolate, e.g. milk chocolate) (5)Available here., (6)Available here.
- Increasing the amount of sugar and other non-cocoa ingredients, decreases the health properties of dark chocolate (7)Available here.
- The plant’s genetic characteristics and where it was grown, influence the polyphenol and toxic metal composition of the final product. (8)Available here.
The healthiest dark chocolate is organic, not alkalized, minimally processed with the highest contents of non-fat cocoa solids and the least amount of sugar.
Health benefits of dark chocolate
The properties of the cocoa’s components may have a significant impact in the prevention of certain medical conditions and decreasing their risk factors.
Some sources consider dark chocolate as a medicinal food.
However, more studies are needed to determine whether eating chocolate has similar health benefits to its individual components. It also needs to be established the dosages and frequencies of chocolate consumption required to exert a significant effect on health.
For instance, an extract of theobromine reduces coughs in cases of acute bronchitis, but eating dark chocolate may not necessarily have the same effect, even though it is very rich in theobromine.
The following is a list the health effects of dark chocolate.
Eating dark chocolate is associated with significantly lower cardiovascular disease risk and stroke, all-cause mortality factors and cardiovascular related mortality. (9)Habitual chocolate consumption and risk of cardiovascular disease among healthy men and women. Available here. (10)Available here., (11)Available here., (12)Cocoa Polyphenols: Can We Consider Cocoa and Chocolate as Potential Functional Food? Available here.
Studies show that consuming 50g of dark chocolate per day may reduce the risk of cardiovascular disease by 10.5%, by reducing some of its main risk factors, such as hypertension, hyperlipidemia, chronic inflammation and insulin resistance. (13)Chocolate and Prevention of Cardiovascular Disease: A Systematic Review. Available here.
Effects of cocoa consumption on the cardiovascular disease risk factors:
- Effects on inflammation
Polyphenols present in cocoa are known to be inflammation markers (14)Available here., (15)Available here., (16)Available here.
Their anti-inflammatory properties are due to the:
- Inhibition of the production of reactive oxygen species (ROS) that cause endothelial dysfunction
- Increase of the antioxidant activity, when combined with vitamin C and selenium
- Prevention of pro-inflammatory substances that cause tissue damage by sticking to the endothelium, resulting in atherosclerosis
- Decreased production of pro-inflammatory and vasoconstrictive leukotrienes
Some of the most important anti-inflammatory polyphenols are epicatechin and procyanidin
- Effects on the interior surface of blood vessels and blood pressure
Nitric oxide is a chemical compound with powerful vasodilating and anti-inflammatory properties.
It has been shown that eating dark chocolate with high flavonols, increases vasodilation and the relaxation of the arteries, by increasing and enhancing the nitric oxide bioactivity in the blood. Vasodilation results in lower systolic and diastolic blood pressure. (17)Available here., (18)Available here. (19)Effects of low habitual cocoa intake on blood pressure and bioactive nitric oxide: a randomized controlled trial. Available here., (20)Magnesium causes nitric oxide independent coronary artery vasodilation in humans. Available here. (21)Available here., (22)Available here.
One hundred grams of dark chocolate consumed daily reduces systolic blood pressure by 5.1 mm Hg and diastolic blood pressure by 1.8 mm Hg. (23)Available here.
These reductions in blood pressure correspond to a reduction in cardiovascular disease events by 21% (14% to 27%) (24)The Polymeal: a more natural, safer, and probably tastier (than the Polypill) strategy to reduce cardiovascular disease by more than 75%. Available here., (25)Available here., (26)Available here.
- Effects on platelets
If the endothelium is damaged through some form of stress, platelets stick to the damaged area and take part in the inflammatory responses and plaque formation.
Cocoa acts like an aspirin. It inhibits the platelet activation, aggregation and adhesion and modulates the primary hemostasis. (27)Available here., (28)Available here.
Flavonols, which are contained in concentrated amounts in cocoa, significantly reduce the platelet activity, and, therefore, the risk of plaque formation.
Stearic acid and certain minerals which are present in cocoa, such as potassium, magnesium and calcium, may also play a role in modulating platelet formation. (29)Flavanols and platelet reactivity. Available here.
- Effects on lipids
Eating dark chocolate significantly reduces LDL cholesterol levels (LDL-c) in people with mildly elevated levels and increases the level of (good) HDL cholesterol (HDL-c) in people with normal or mildly elevated levels. (30)Available here., (31)Available here., (32)Available here.
Furthermore, the oxidation of LDLs leads to atherosclerosis and increases the risk of cardiovascular disease. (read more..) (33)Available here., (34)Available here.
Although there are conflicting studies, most evidence shows that the consumption of dark chocolate protects lipids from oxidation.
For more details on the effects of eating dark chocolate on heart health, see “Human Trials Investigating Cardiovascular Effects of Cocoa or chocolate.”
Insulin resistance and type 2 diabetes
Insulin sensitivity is improved by the action of polyphenols, such as catechin and epicatechin. They decrease oxidative stress, improve endothelial function and alter glucose metabolism. (35)Available here., (36)Available here.
In addition to reducing insulin resistance and improving glucose tolerance, polyphenols may also induce beta cell regeneration and stimulate the secretion of insulin.
All of these effects are known to reduce the risk of type 2 diabetes.
Nevertheless, please note that consuming dark chocolate on a regular basis for extended periods of time is more effective than eating it sporadically.
On the other hand, there is limited information on the glycemic index (GI) and glycemic load (GL) effects of dark chocolates.
A 50g serving of dark chocolate, with cocoa solids of about 50%, and roughly a 50-50% ratio of fat to carbohydrates, has a low GI=23 and only a GL of 6. (37)Glycemic Index of dark chocolate. Available here.
Despite the current unavailability of lab data (only some estimates (38)Glycemic Index of dark chocolate. 70-85% Cocoa. Available here.) regarding GI and GL levels on higher cocoa percentages of chocolate, we can safely assume that since 50-50 cocoa to sugar ratio has low GI and GL, that chocolates with at least 70% cocoa, have even smaller GI and GL.
Therefore, the higher the percentage of cocoa chocolate, the safer it is for diabetics.
Immunity and Cancer
Although there are no studies of the cocoa effects on the immune system in humans, there are some preliminary studies performed on rats and in-vitro.
These indicate that cocoa antioxidants may play an important part in immunity, by decreasing DNA damage through the reduction of oxidation and inflammation. (39)Available here., (40)Available here.
The cocoa’s powerful antioxidant properties and its ability to enhance apoptosis of cancer cells (41)Available here. may also have a key role in reducing the risk of cancer.
NOTE: there are no studies on the effects of cocoa consumption on cancer in humans.
Central nervous system
Preliminary studies show that epicatechin has a relevant role in the formation of long-term memory. (42)Available here. These studies also indicate that cocoa’s flavonoids improve cerebral blood flow (43)Available here. and may be protective against neurodegeneration, and neuroinflammation, which are linked to neurological conditions, such as Parkinsons, Alzheimers and stroke.
NOTE: there are no clinical trials on the effects of cocoa consumption on neuroprotective properties on humans
Effects on skin
Cocoa butter topical application is known to be effective, but specific studies on the effects of the consumption of dark chocolate on the skin are limited.
The consumption of chocolate high in flavonols has been shown to decrease the UV light induced erythema (redness of the skin) by 25%. However, the chocolate used in this study is not commercially available. (44)Available here.
Nevertheless, flavonols may have skin protective properties, because they cause an increase of blood flow to the skin, delivering oxygen, micro nutrients and improving thermoregulation. (45)Available here.
NOTE: more studies on humans are needed to prove that dark chocolate consumption can be effective in skin health.
Cadmium and lead bind to cocoa’s insoluble substances, are resistant to gastrointestinal conditions and a significant proportion of these metals are excreted. Such properties indicate a possible detoxifying effect of cocoa. More studies are needed. (46)Bioavailability of cadmium and lead in cocoa: comparison of extraction procedures prior to size-exclusion fast-flow liquid chromatography with inductively coupled plasma mass spectrometric detection (SEC-ICP-MS). Available here.
Effects on obesity
On the one hand, dark chocolate is a high caloric food and can be indulgent. On the other hand, its constituents alter the metabolism of fat and sugar in the body.
The plausible reason for the lack of weight gain is due to the improvement of insulin sensitivity, lipid metabolism and update of glucose.
Smelling and eating dark chocolate may also reduce appetite and increase satiety. (49)Available here.
Overall, findings show that weight gain is at most negligible with a moderate consumption of dark chocolate and its health benefits override that risk, even in obese individuals. (50)Available here.
Chocolate may be associated with a better cognitive function, due to its high flavanol and methylxanthine contents, but more studies are needed. (51)Available here.
Dark chocolate can positively affect mood in the short term and this is believed to result from its taste and texture rather than the chemistry of its components. (52)Available here., (53)Cocoa Polyphenols: Can We Consider Cocoa and Chocolate as Potential Functional Food? Available here., (54)Mood state effects of chocolate. Available here.
Despite a popular belief, there is no scientific evidence that cocoa or chocolate consumption have an aphrodisiac effect and increase sexual desire or pleasure in women. (55)ORIGINAL RESEARCH—WOMEN’S SEXUAL HEALTH: Chocolate and Women’s Sexual Health: An Intriguing Correlation. Available here.
Low NO production is associated with not only hypertension, but erectile dysfunction. Although high cocoa dark chocolate consumption increases vascular nitric oxide (NO) production, improving vascular blood flow and reducing blood pressure, more studies are needed that show that eating dark chocolate improves men’s sexual function. (56)The Link Between Erectile and Cardiovascular Health: The Canary in the Coal Mine. Available here., (57)Integrated Approach to Hypertension. Available here.
Nutritional value of chocolate
In addition to the high amount of polyphenols and theobromine, chocolate is a very nutritious food. As mentioned before, it contains plenty of fiber, and is a great source of minerals, such as copper, magnesium, iron, zinc, manganese and phosphorus.
Its fatty component is rich in oleic acid – monounsaturated fatty acid (also a component of olive oil). (read more..)
High cocoa dark chocolate consumption:
- reduces the risk of cardiovascular disease through various mechanisms
- improves insulin sensitivity,
- may be play important role in immunity and protection against neurodegeneration diseases, skin health,
- is a great source of copper, magnesium, iron, zinc, manganese and phosphorus
Negative health effects of eating dark chocolate
Chocolate is not for everybody. Eating it may have some negative health effects on some sensitive people. However the evidence varies across sources and is often inconclusive.
Chocolate has shown to lower the esophageal sphincter pressure (loosening the muscle between esophagus and stomach) and exacerbate heartburn symptoms or gastroesophageal reflux disease (GERD). Nevertheless, studies haven’t yet proven conclusively that stopping chocolate consumption reduces these symptoms. (58)Available here. (59)Chocolate and heartburn: evidence of increased esophageal acid exposure after chocolate ingestion. Available here.
There are some reports of chocolate causing migraines in sensitive people. Phenylethylamine is one of the possible suspects for this effect. However, the evidence is weak. (60)Trigger factors of migraine and tension-type headache: experience and knowledge of the patients. Available here.
A double-blind study, for instance, has found that chocolate does not play a significant role as a cause of headaches. (61)A Double-Blind Provocative Study Chocolate as A Trigger of Headache. Available here.
- Weight gain
Dark chocolate is high in calories and may cause concern, if consumed as part of an unhealthy diet. However, a potential weight gain is not due to the cocoa components but rather due to its high caloric value and high sugar contents, together with an overall unhealthy diet. (62)Available here.
Chocolate has been reported to cause acne, but this claim is not supported by scientific studies. The reports may be associated with other ingredients of chocolate products rather than the cocoa component, such as sugar or milk. (63)Does diet really affect acne? Available here.
Chocolate consumption may cause constipation in some people. (64)The perceived effect of various foods and beverages on stool consistency. Available here.
- Toxic metals
Cocoa shells can contain significant amounts of toxic bismuth and arsenic. Therefore, although cocoa shells may be loaded with healthy polyphenols, chocolates with blended shells may be harmful overall. (65)Trace elements in cocoa solids and chocolate: an ICPMS study. Available here.
Furthermore, cocoa has some trace amounts of cadmium and lead. If taken in large amounts, these metals may be toxic. However, in cocoa, a proportion of these metals bind to insoluble substances and are excreted. (66)Bioavailability of cadmium and lead in cocoa: comparison of extraction procedures prior to size-exclusion fast-flow liquid chromatography with inductively coupled plasma mass spectrometric detection (SEC-ICP-MS). Available here., (67)Satarug S, Haswell-Elkins MR, Moore MR. Safe levels of cadmium intake to prevent renal toxicity in human subjects. Br J Nutr. 2000 Dec;84(6):791-802. Available here., (68)Available here.
Although some chocolates have been shown to contain amounts of cadmium that are higher than recommended by WHO, in adults the bioavailability of toxic metals in cocoa is very low.
Please be aware that there are warnings that excessive amounts of dark chocolate may be unsafe for children due to these heavy metals. A 10g piece of dark chocolate may contain as much as 20% of the daily lead oral limit. (69)Trace elements in cocoa solids and chocolate: an ICPMS study. Available here.
- Some sensitive people may experience worsening of reflux symptoms, migraine or acne. There is no strong evidence that cocoa components are the cause.
- Eating too much dark chocolate may result in constipation.
- Toxic metal in dark chocolate may affect children who eat dark chocolate in excess.
Provided that you don’t suffer from any specific side-effect, eating a dark chocolate low in sugar and high in non-fat cocoa solids provides a wide range of health benefits, especially in the prevention of cardiovascular diseases.
Since the consumption of moderate amounts of dark chocolate doesn’t have a significant effect on weight gain, it can be a great nutritional addition to our diet.
Please note, however, that there are no conclusive studies indicating the type, amounts and frequency of chocolate consumption that are optimal for our health.
It is also not known for which populations chocolate is beneficial and for which is potentially detrimental.
References [ + ]
|9.||↑||Habitual chocolate consumption and risk of cardiovascular disease among healthy men and women. Available here.|
|12.||↑||Cocoa Polyphenols: Can We Consider Cocoa and Chocolate as Potential Functional Food? Available here.|
|13.||↑||Chocolate and Prevention of Cardiovascular Disease: A Systematic Review. Available here.|
|19.||↑||Effects of low habitual cocoa intake on blood pressure and bioactive nitric oxide: a randomized controlled trial. Available here.|
|20.||↑||Magnesium causes nitric oxide independent coronary artery vasodilation in humans. Available here.|
|24.||↑||The Polymeal: a more natural, safer, and probably tastier (than the Polypill) strategy to reduce cardiovascular disease by more than 75%. Available here.|
|29.||↑||Flavanols and platelet reactivity. Available here.|
|37.||↑||Glycemic Index of dark chocolate. Available here.|
|38.||↑||Glycemic Index of dark chocolate. 70-85% Cocoa. Available here.|
|46.||↑||Bioavailability of cadmium and lead in cocoa: comparison of extraction procedures prior to size-exclusion fast-flow liquid chromatography with inductively coupled plasma mass spectrometric detection (SEC-ICP-MS). Available here.|
|53.||↑||Cocoa Polyphenols: Can We Consider Cocoa and Chocolate as Potential Functional Food? Available here.|
|54.||↑||Mood state effects of chocolate. Available here.|
|55.||↑||ORIGINAL RESEARCH—WOMEN’S SEXUAL HEALTH: Chocolate and Women’s Sexual Health: An Intriguing Correlation. Available here.|
|56.||↑||The Link Between Erectile and Cardiovascular Health: The Canary in the Coal Mine. Available here.|
|57.||↑||Integrated Approach to Hypertension. Available here.|
|59.||↑||Chocolate and heartburn: evidence of increased esophageal acid exposure after chocolate ingestion. Available here.|
|60.||↑||Trigger factors of migraine and tension-type headache: experience and knowledge of the patients. Available here.|
|61.||↑||A Double-Blind Provocative Study Chocolate as A Trigger of Headache. Available here.|
|63.||↑||Does diet really affect acne? Available here.|
|64.||↑||The perceived effect of various foods and beverages on stool consistency. Available here.|
|65.||↑||Trace elements in cocoa solids and chocolate: an ICPMS study. Available here.|
|66.||↑||Bioavailability of cadmium and lead in cocoa: comparison of extraction procedures prior to size-exclusion fast-flow liquid chromatography with inductively coupled plasma mass spectrometric detection (SEC-ICP-MS). Available here.|
|67.||↑||Satarug S, Haswell-Elkins MR, Moore MR. Safe levels of cadmium intake to prevent renal toxicity in human subjects. Br J Nutr. 2000 Dec;84(6):791-802. Available here.|
|69.||↑||Trace elements in cocoa solids and chocolate: an ICPMS study. Available here.|