Health effects of chocolate
||This article needs more medical references for verification or relies too heavily on primary sources. (January 2013)|
The health effects of chocolate refer to the possible beneficial or detrimental physiological effects of eating chocolate mainly for pleasure. For example, cocoa and dark chocolate may support cardiovascular health. Other effects under preliminary research include reduced risks of cancer, coughing and heart disease. One interpretation on the potential health effects of dietary chocolate is it may lower blood pressure, improve vascular function and energy metabolism, and reduce platelet aggregation and adhesion.
Unconstrained consumption of large quantities of any energy-rich food, such as chocolate, without a corresponding increase in activity, increases the risk of obesity. Raw chocolate is high in cocoa butter, a fat removed during chocolate refining, then added back in varying proportions during manufacturing. Manufacturers may add other fats, sugars, and powdered milk as well.
Potential effects in the body
Research on rats has determined that increased chocolate intake enhances the expression of MKP in the trigeminal ganglion, lowering the level of CGRP and other inflammatory chemicals possibly involved in mechanisms of migraines.
Limited research indicates that cocoa or dark chocolate may produce certain effects on human health. In test tubes, cocoa has antioxidant activity, an effect not proved in the body. Chocolate phenols may affect arteries and inhibit lipid oxidation, but this research has not been adequately confirmed. Some studies have also observed a modest reduction in blood pressure and flow-mediated dilation after consuming dark chocolate daily. Consuming milk chocolate or white chocolate, or drinking fat-containing milk with dark chocolate, appears to largely negate the health benefit. Processing cocoa powder (Dutch process chocolate) with alkali may reduce antioxidant properties compared to raw cocoa powder.
One-third of the fat in chocolate comes from the monounsaturated fat oleic acid, another third from the saturated fat stearic acid, and a third from saturated fat palmitic acid. However, unlike other saturated fats, stearic acid does not raise levels of LDL cholesterol in the bloodstream and has neutral effects on cholesterol. Stearic acid can be converted to oleic acid in the liver. Consuming relatively large amounts of dark chocolate and cocoa has not been adequately studied to determine if serum LDL cholesterol levels are altered. In one study, small but regular amounts of dark chocolate were associated with a lower risk of a heart attack.
Another study using long-term consumption of chocolate showed an increase of HDL cholesterol by 11% which appreared to be enhanced by addition of cocoa polyphenols.
Another study found that survivors of heart attacks who ate chocolate at least two or three times a week reduced their risk of death by a factor of up to three times compared to survivors who did not eat chocolate or other sweets.
In a Swiss study a group of 20 smokers were given 40 grams of chocolate. Two hours after consuming the chocolate, the echo-graph showed that dark chocolate, with a cocoa percent of at least 74%, significantly improved the blood flow. Additionally, ulterior tests showed that the risk of encountering blood accidents and blockages has been decreased to half of the initial risk.
Romantic lore commonly identifies chocolate as an aphrodisiac. The reputed aphrodisiac qualities of chocolate are most often associated with the simple sensual pleasure of its consumption. Although there is no proof that chocolate is indeed an aphrodisiac, a gift of chocolate is a familiar courtship ritual. Research looking at the psychoactivity of chocolate reveals that methylxanthine, an active biological substance found in chocolate, competes with adenosine, a presynaptic inhibitor modulator, and blocks its receptor. This induced blockage can lead to arousal. The participants' blood pressure decreased, and they showed improvements in insulin sensitivity, meaning they were better able to metabolize glucose.
A concern that nutritionists have is that excessive consumption of dark chocolate may promote weight gain and obesity which are risk factors for many diseases, including cardiovascular disease. As a consequence, consuming large quantities of dark chocolate in an attempt to protect against cardiovascular disease has been described as 'cutting off one's nose to spite one's face'.
There is a popular belief that the consumption of chocolate can cause acne. This belief is not supported by scientific studies. Various studies point not to chocolate, but to the high glycemic nature of certain foods, like sugar, corn syrup, and other simple carbohydrates, as a cause of acne. Chocolate itself has a low glycemic index. Other dietary causes of acne cannot be excluded yet, but more rigorous research is suggested.
Chocolate contains a variety of substances, some of which may have an effect on body chemistry. These include:
- Caffeine, present in smaller amounts
- Methylated xanthines (theobromine, caffeine & theophylline)
- Monoamine oxidase
- Oxalic acid
- Phenethylamine, an endogenous alkaloid sometimes described as a 'love chemical; it is quickly metabolized by monoamine oxidase-B and does not reach the brain in significant amounts
- Theobromine, the primary alkaloid in cocoa solids and chocolate and partly responsible for chocolate's mood-elevating effect
- Tryptophan, an essential amino acid and precursor to serotonin
- Tyramine, found in processed chocolate (not raw cacao) after fermentation.
White chocolate contains only trace amounts of the caffeine and theobromine of normal chocolates, because these chemicals are contained in the cocoa solids, not the cocoa butter, from which white chocolate is made.
Chocolate consumption may have potential to cause mild lead poisoning, as some studies have shown that lead may bind to cocoa shells and contamination may occur during the manufacturing process. In a USDA study in 2004, mean lead levels in the samples tested ranged from 0.0010 to 0.0965 µg lead per gram of chocolate, but another study by a Swiss research group in 2002 found that some chocolate contained up to 0.769 µg per gram, close to the international (voluntary) standard limit for lead in cocoa powder or beans, which is 1 µg of lead per gram. In 2006, the U. S. FDA lowered by one-fifth the amount of lead permissible in candy, but compliance is only voluntary.
Chocolate contains polyphenols, especially flavan-3-ols (catechins) and flavonoids which are under study for their potential effects in the body. The following table shows the phenolic and flavonoid content of three different types of chocolate.
|Type of chocolate||Total phenolics (mg/100g)||Flavonoids (mg/100g)|
Potential toxicity in animals
In sufficient amounts, the theobromine found in chocolate is toxic to animals such as horses, dogs, parrots, small rodents, and cats because they are unable to metabolise the chemical effectively. If animals are fed chocolate, the theobromine may remain in the circulation for up to 20 hours, possibly causing epileptic seizures, heart attacks, internal bleeding, and eventually death. Medical treatment performed by a veterinarian involves inducing vomiting within two hours of ingestion and administration of benzodiazepines or barbiturates for seizures, antiarrhythmics for heart arrhythmias, and fluid diuresis.
A typical 20-kilogram (44 lb) dog will normally experience great intestinal distress after eating less than 240 grams (8.5 oz) of dark chocolate, but will not necessarily experience bradycardia or tachycardia unless it eats at least a half a kilogram (1.1 lb) of milk chocolate. Dark chocolate has 2 to 5 times more theobromine and thus is more dangerous to dogs. According to the Merck Veterinary Manual, approximately 1.3 grams of baker's chocolate per kilogram of a dog's body weight (0.02 oz/lb) is sufficient to cause symptoms of toxicity. For example, a typical 25-gram (0.88 oz) baker's chocolate bar would be enough to bring about symptoms in a 20-kilogram (44 lb) dog. Of course, baking chocolate is rarely consumed directly due to its unpleasant taste, but other dark chocolates' canine toxicities may be extrapolated based on this figure. Given access, dogs frequently consume chocolate at toxic levels because they like the taste of chocolate products and are capable of finding and eating quantities much larger than typical human servings. There are reports that mulch made from cacao bean shells is dangerous to dogs and livestock.
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