What Causes Acne?

How Acne Develops  

Acne happens when sebaceous (oil) glands attached to the hair follicles are stimulated at the time of puberty by elevated levels of male hormones. Sebum (oil) is a natural substance which l
ubricates and protects the skin. Associated with increased oil production is a change in the manner in which the skin cells mature so that they are predisposed to clog the follicular openings or pores. The clogged hair follicle gradually enlarges, producing a bump. As the follicle enlarges, the wall may rupture, allowing irritating substances and normal skin bacteria access into the deeper layers of the skin, ultimately producing inflammation.

Inflammation near the skin's surface produces a pustule; deeper inflammation results in a papule (pimple); deeper still and it's a cyst. If the oil breaks though to the surface, the result is a "whitehead." If the oil accumulates melanin pigment or becomes oxidized, the oil changes from white to black, and the result is a "blackhead." Blackheads are therefore not dirt and do not reflect poor hygiene.

Here are some factors that don't usually play a role in acne:

• Heredity: With the exception of very severe acne, most people do not have the problem exactly as their parents did. Almost everyone has some acne at some point in their life.

• Food: Parents often tell teens to avoid pizza, chocolate, greasy and fried foods, and junk food. While these foods may not be good for overall health, they don't cause acne or make it worse. Although some recent studies have implicated milk and pure chocolate in aggravating acne, these findings are very far from established

• Dirt: As mentioned above, "blackheads" are oxidized oil, not dirt. Sweat does not cause acne, therefore, it is not necessary to shower instantly after exercise for fear that sweat will clog pores. On the other hand, excessive washing can dry and irritate the skin.

• Stress: Some people get so upset by their pimples that they pick at them and make them last longer. Stress, however, does not play much of a direct role in causing acne.

In occasional patients, the following may be contributing factors:

• Pressure: In some patients, pressure from helmets, chin straps, collars, suspenders, and the like can aggravate acne.

• Drugs: Some medications may cause or worsen acne, such as those containing iodides, bromides, or oral or injected steroids (either the medically prescribed prednisone [Deltasone, Orasone, Prednicen-M, Liquid Pred] or the steroids that bodybuilders or athletes take). Other drugs that can cause or aggravate acne are anticonvulsant medications and lithium (Eskalith, Lithobid), which is used to treat bipolar disorder. Most cases of acne, however, are not drug related.

• Occupations: In some jobs, exposure to industrial products like cutting oils may produce acne.

• Cosmetics: Some cosmetics and skin-care products are pore clogging ("comedogenic"). Of the many available brands of skin-care products, it is important to read the list of ingredients and choose those which have water listed first or second if you are concerned about acne. These "water-based" products are usually safe.

< Signs And Symptoms                                                                           Diagnosis >

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Treatment for Acna

If you haven't been able to control your acne adequately, you may want to consult a primary-care physician or dermatologist. The goal of treatment should be the prevention of scarring (not a flawless complexion) so that after the condition spontaneously resolves there is no lasting sign of the affliction. Here are some of the options available:

• Topical (externally applied) antibiotics and antibacterials: These include erythromycin (E-Mycin, Eryc, Ery-Tab, PCE, Pediazole, Ilosone),clindamycin (BenzaClin, Duac), sulfacetamide (Klaron), and azelaic acid(Azelex or Finacea).
• Retinoids: Retin-A (tretinoin) has been around for years, and preparations have become milder and gentler while still maintaining its effectiveness. Newer retinoids include adapalene (Differin) and tazarotene (Tazorac). These medications are especially helpful for unclogging pores. Side effects may include irritation and a mild increase in sensitivity to the sun. With proper sun protection, however, they can be used even during sunny periods. In December 2008, the U.S. FDA approved the combination medication known as Epiduo gel, which contains the retinoid adapalene along with the antibacterial cleanser benzoyl peroxide. This once-daily prescription treatment was approved for use in patients 12 years of age and older.
• Oral antibiotics: Doctors may start treatment with tetracycline(Sumycin) or one of the related "cyclines," such as doxycycline(Vibramycin, Oracea, Adoxa, Atridox and others) and minocycline(Dynacin, Minocin). Other oral antibiotics that are useful for treating acne are cefadroxil (Duricef), amoxicillin (Amoxil, DisperMox, Trimox), and the sulfa drugs.
• Problems with these drugs can include allergic reactions (especially sulfa), gastrointestinal upset, and increased sun sensitivity. Doxycycline, in particular, is generally safe but can sometime cause esophagitis (irritation of the esophagus, producing discomfort when swallowing) and an increased tendency to sunburn.
• Despite many people's concerns about using oral antibiotics for several months or longer, such use does not "weaken the immune system" and make them more susceptible to infections or unable to use other antibiotics when necessary.
• Recently published reports that long-term antibiotic use may increase the risk of breast cancer will require further study, but at present they are not substantiated. In general, doctors prescribe oral antibiotic therapy for acne only when necessary and for as short a time as possible.
• Oral contraceptives: Oral contraceptives, which are low in estrogen to promote safety, have little effect on acne one way or the other. Some contraceptive pills have been to shown to have modest effectiveness in treating acne. Those FDA approved for treating acne are Estrostep,Ortho Tri-Cyclen, and Yaz. Most dermatologists work together with primary physicians or gynecologists when recommending these medications.

• Spironolactone (Aldactone): This drug blocks androgen (hormone) receptors. It can cause breast tenderness, menstrual irregularities, and increased potassium levels in the bloodstream. It can help some women with resistant acne, however, and is generally well-tolerated in the young women who need it.

• Cortisone injections: To make large pimples and cysts flatten out fast, doctors inject them with a form of cortisone.

• Isotretinoin: (Accutane was the original brand name; there are now several generic versions in common use, including Sotret, Claravis, and Amnesteem.) Isotretinoin is an excellent treatment for severe, resistant acne and has been used on millions of patients since it was introduced in Europe in 1971 and in the U.S. in 1982. It should be used for people with severe acne, chiefly of the cystic variety, which has been unresponsive to conventional therapies like those listed above. The drug has many potential serious side effects and requires a number of unique controls before it is prescribed. This means that isotretinoin is not a good choice for people whose acne is not that bad but who are frustrated and want "something that will knock acne out once and for all."
• Used properly, isotretinoin is safe and produces few side effects beyond dry lips and occasional muscle aches. This drug is prescribed for five to six months. Fasting blood tests are monitored monthly to check liver function and the level of triglycerides, substances related to cholesterol, which often rise a bit during treatment, but rarely to the point where treatment has to be modified or stopped.
• Even though isotretinoin does not remain in the body after therapy is stopped, improvement is often long-lasting. It is safe to take two or three courses of the drug if unresponsive acne makes a comeback. It is, however, best to wait at least several months and to try other methods before using isotretinoin again.
• Isotretinoin has a high risk of inducing birth defects if taken by pregnant women. Women of childbearing age who take isotretinoin need two negative pregnancy tests (blood or urine) before starting the drug, monthly tests while they take it, and another after they are done. Those who are sexually active must use two forms of contraception, one of which is usually the oral contraceptive pill. Isotretinoin leaves the body completely when treatment is done; women must be sure to avoid pregnancy for one month after therapy is stopped. There is, however, no risk to childbearing after that time.
• Other concerns include inflammatory bowel disease and the risk of depression and suicide in patients taking isotretinoin. Government oversight has resulted in a highly publicized and very burdensome national registration system for those taking the drug. This has reinforced concerns in many patients and their families have that isotretinoin is dangerous. In fact, large-scale studies so far have shown no convincing evidence of increased risk for those taking isotretinoin compared with the general population. It is important for those taking this drug to report changes in mood or bowel habits (or any other symptoms) to their doctors. Even patients who are being treated for depression are not barred from taking isotretinoin, whose striking success often improves the mood and outlook of patients with severe disease.
• Laser treatments: Recent years have brought reports of success in treating acne using lasers and similar devices, alone or in conjunction with photosensitizing dyes. It appears that these treatments are safe and can be effective, but it is not clear that their success is lasting. At this point, laser treatment of acne is best thought of as an adjunct to conventional therapy, rather than as a substitute.
• Chemical peels: Whether the superficial peels (like glycolic acid) performed by aestheticians or deeper ones performed in the doctor's office, chemical peels are of modest, supportive benefit only, and in general, they do not substitute for regular therapy.
• Treatment of acne scars: For those patients whose acne has gone away but left them with permanent scarring, several options are available. These include surgical procedures to elevate deep, depressed acne scars and laser resurfacing to smooth out shallow acne scars. Newer forms of laser resurfacing ("fractional resurfacing") are less invasive and heal faster than older methods, although results are less complete and they may need to be repeated three or more times. These treatments can help, but they are never completely successful at eliminating acne scars.

What are other things you can do for acne?

• Cosmetics: Don't be afraid to hide blemishes with flesh-tinted coverups or even foundation, as long at it is water-based (which makes it noncomedogenic). There are many quality products available.
• Facials: While not absolutely essential, steaming and "deep-cleaning" pores is useful, both alone and in addition to medical treatment, especially for people with "whiteheads" or "blackheads."Having these pores unclogged by a professional also reduces the temptation to do it yourself.
• Pore strips: Pharmacies now carry, under a variety of brand names, strips which you put on your nose, forehead, chin, etc., to "pull out" oil from your pores. These are, in effect, a do-it-yourself facial. They are inexpensive, safe, and work reasonably well if used properly.
• Toothpaste? One popular home remedy is to put toothpaste on zits. There is no medical basis for this. Ditto for vinegar.

What is a good basic skin regimen?

These are all good basic skin regimens that may help with the acne battle:

1. Cleanse twice daily with a 5% benzoyl peroxide wash. An alternative for those who are allergic to benzoyl peroxide is 2% salicylic acid.
2. Apply a gel or cream containing 5% benzoyl peroxide; an alternative is sulfur or resorcinol.
3. At night, apply a spot cream containing sulfur to the affected areas.
4. Use a light skin moisturizer and water-based oil-free makeup.

< Diagnosis

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Diagnose Acne

There is no medical test used to diagnose acne. A diagnosis is made only with a visual examination. Most people can recognize and diagnose acne themselves; however, there is a tendency to overreact. One zit or one pimple does not constitute a full-blown case of the disease.

However, if you are unsure if what you are experiencing is acne, or if your acne seems severe, see your dermatologist.

Some skin conditions can look remarkably similar to acne, although their causes and treatments are different. Do you have acne or an acne look-alike condition? If you are unsure, it is always wise to consult with a doctor. Common skin conditions that can be mistaken for acne include:

• Rosacea - Causes red, flushed skin with papules and pustules, especially in the nose and cheek area.
• Folliculitis - Bumps or pustules caused by inflammation of the hair follicle.
• Keratosis pilaris - Small, rough, "goose-flesh" like bumps most often found on the upper arms, thighs and buttocks, and sometimes the face.
• Miliaria rubra - Small red bumps on the surface of the skin caused by excessive heat exposure. Also known as heat rash.

< Causes                                                                    Treatment And Menagment >                 

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Signs And Types Of Acne

Acne typically appears on your face, neck, chest, back and shoulders, which are the areas of your skin with the largest number of functional oil glands. Acne can take the following forms:

Comedones (whiteheads and blackheads) are created when the openings of hair follicles become clogged and blocked with oil secretions, dead skin cells and sometimes bacteria. When comedones (kom-uh-DOE-neze) are open at the skin surface, they're called blackheads because of the dark appearance of the plugs in the hair follicles. When comedones are closed, they're called whiteheads — slightly raised, skin-colored bumps.
Papules are small raised bumps that signal inflammation or infection in the hair follicles. Papules may be red and tender.
Pustules are red, tender bumps with white pus at their tips.
Nodules are large, solid, painful lumps beneath the surface of the skin. They're formed by the buildup of secretions deep within hair follicles.
Cysts are painful, pus-filled lumps beneath the surface of the skin. These boil-like infections can cause scars.

When to see a doctor

Acne usually isn't a serious medical condition. But you may want to seek medical treatment from a dermatologist for persistent pimples or inflamed cysts to avoid scarring or other damage to your skin. If acne and the scars it may have left are affecting your social relationships or self-esteem, you may also want to ask a dermatologist if your acne can be controlled or if your scars can be diminished.

<Introduction                                                                                              Causes >

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Acne

Acne (acne vulgaris, common acne) is a disease of the hair follicles of the face, chest, and back that affects almost all males and females during puberty; the only exception being teenage members of a few primitive isolated tribes living in Neolithic societies. It is not caused by bacteria, although bacteria play a role in its development. It is not unusual for some women to develop acne in their mid- to late-20s.

Acne can be distressing and annoyingly persistent. Acne lesions heal slowly, and when one begins to resolve, others seem to crop up.

Acne appears on the skin as:

• congested pores ("comedones"), also known as blackheads or whiteheads, 
• tender red bumps also known as pimples or zits, 
• pustules, and occasionally as 
• cysts (deep pimples, boils).

                                                                                                                               Sings and Symptoms >

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Chocolate and Fried Foods Give You Acne

Some speculate that this myth dates back to the baby-boom generation, who had worse acne than their parents and also more access to chocolate and fried foods. Wherever this idea came from, it's wrong. Pimples form when oil glands under the skin produce too much of a waxy oil called sebum, which the body uses to keep skin lubricated. But when excess sebum and dead skin cells block pores, that area of the skin gets irritated, swollen, and turns red -- the telltale signs of a pimple. It is unknown why sebaceous glands produce excess sebum, but hormones are the prime suspects, which explains why teenagers are affected more than others. Stress and heredity may also be factors, but chocolate bars and onion rings are off the hook.

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Cold Weather Can Give You a Cold

"Put your jacket on or you'll catch a cold!" How times have you heard that? You may not want to tell her this, but dear old Mom was wrong. Viruses (more than 200 different kinds) cause colds, not cold weather. In order for you to catch a cold, the virus must travel from a sick person's body to yours. This usually happens via airborne droplets you inhale when an infected person coughs or sneezes. You can also get a cold virus by shaking hands with an infected person or by using something where the virus has found a temporary home, such as a phone or door handle. Colds are more prevalent during the colder months because people tend to spend more time inside, making it much easier for viruses to jump from person to person.

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Spot Diagnosis 001

A 67-year-old male subject with severe hemithorax pain and dyspnea, along with disseminated pain and muscle weakness in the right shoulder and down the arm.


What is your diagnosis and do you know what symptoms, other than pain in shoulder, can this condition cause?

The correct answer is!

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Chocolate Good for the Heart and Brain

Chocolate consumption and cardiometabolic disorders: systematic review and meta-analysis

Abstract

Objective To evaluate the association of chocolate consumption with the risk of developing cardiometabolic disorders.

Design Systematic review and meta-analysis of randomised controlled trials and observational studies.

Data sources Medline, Embase, Cochrane Library, PubMed, CINAHL, IPA, Web of Science, Scopus, Pascal, reference lists of relevant studies to October 2010, and email contact with authors.

Study selection Randomised trials and cohort, case-control, and cross sectional studies carried out in human adults, in which the association between chocolate consumption and the risk of outcomes related to cardiometabolic disorders were reported.

Data extraction Data were extracted by two independent investigators, and a consensus was reached with the involvement of a third. The primary outcome was cardiometabolic disorders, including cardiovascular disease (coronary heart disease and stroke), diabetes, and metabolic syndrome. A meta-analysis assessed the risk of developing cardiometabolic disorders by comparing the highest and lowest level of chocolate consumption.

Results From 4576 references seven studies met the inclusion criteria (including 114 009 participants). None of the studies was a randomised trial, six were cohort studies, and one a cross sectional study. Large variation was observed between these seven studies for measurement of chocolate consumption, methods, and outcomes evaluated. Five of the seven studies reported a beneficial association between higher levels of chocolate consumption and the risk of cardiometabolic disorders. The highest levels of chocolate consumption were associated with a 37% reduction in cardiovascular disease (relative risk 0.63 (95% confidence interval 0.44 to 0.90)) and a 29% reduction in stroke compared with the lowest levels.

Conclusions Based on observational evidence, levels of chocolate consumption seem to be associated with a substantial reduction in the risk of cardiometabolic disorders. Further experimental studies are required to confirm a potentially beneficial effect of chocolate consumption.

Introduction

According to the World Health Organization, by 2030 nearly 23.6 million people will die from cardiovascular disorders. Furthermore, about a fifth of the world’s adult population are thought to have metabolic syndrome, a cluster of factors associated with an increased risk of type 2 diabetes and cardiovascular disease. This increase in cardiometabolic disorders exerts a great burden on people, healthcare organisations, and society in general. However, cardiometabolic disorders are largely preventable, and a better understanding of the factors associated in their physiopathogenesis and implementation of interventions to modify these factors will be critical in tackling the current epidemic.

Diet is one of the key lifestyle factors involved in the genesis, prevention, and control of cardiometabolic disorders. Cocoa products containing flavonol have been shown to have an encouraging potential to help prevent cardiometabolic disorders. Recent studies (both experimental and observational) have suggested that chocolate consumption has a positive influence on human health, with antioxidant, antihypertensive, anti-inflammatory, anti-atherogenic, and anti-thrombotic effects as well as influence on insulin sensitivity, vascular endothelial function, and activation of nitric oxide. These beneficial effects have been confirmed in recent reviews and meta-analyses, supporting the positive role of cacao and cocoa products on cardiovascular risk factors such as blood pressure, cholesterol levels, atherosclerosis, and insulin resistance. However, most of the existing evidence is on intermediate factors of cardiovascular disorders, and it remains unclear whether chocolate consumption is related to reductions in hard cardiovascular outcomes (such as myocardial infarction and stroke).

We carried out a systematic review and meta-analysis of the scientific literature to evaluate the association between chocolate intake and the risk of developing cardiometabolic disorders, including cardiovascular disease (stroke, heart failure, and myocardial infarction), diabetes, and metabolic syndrome. We also evaluated whether this association would differ by type of cardiometabolic disorder, sex, and study characteristics.

Methods

We carried out a systematic review and meta-analysis of studies that evaluated the association between chocolate consumption and cardiometabolic disorders in adults. Between June 2010 and 5 October 2010 (last date searched) we searched Medline (1950 to present), Embase (1980 to present), the Cochrane Library (1960 to present), Scopus (1996 to present), Scielo (1997 to present), Web of knowledge (1970 to present), AMED (1985 to present), and CINHAL (1981 to present).

We used combinations of text words and thesaurus terms that included cacao[Mesh], cacao[Title/Abstract]*, chocolate, chocolate*[Title/Abstract], cocoa, cocoa*[Title/Abstract], cardiovascular diseases [Mesh], cardiovascular disease, cardiovascular, coronary artery disease [Mesh], atherosclerosis [Mesh], coronary disease [Mesh], coronary heart disease, coronary, myocardial, ischaemic heart disease, ischaemic heart disease*[Title/Abstract], ischemic heart disease, ischemic heart disease*[Title/Abstract], Heart Failure[Mesh], myocardial infarction [Mesh], myocardial ischemia [Mesh], stroke, stroke [Mesh], cerebral stroke, stroke, brain vascular accident, cerebrovascular stroke, cerebrovascular accident, cerebral vascular, cerebral vascular accident, cerebrovascular CVA, metabolic syndrome X [Mesh], metabolic syndrome, metabolic cardiovascular syndrome*[title/abstract], diabetes type 2, diabeti, diabete, diabet*[title/abstract], diabetes mellitus [Mesh], diabetes mellitus, type 2 [Mesh].

Studies were included if they were randomised controlled trials or cohort, case-control, or cross sectional studies; carried out in adults (≥18 years old); studied the effects of levels of chocolate consumption; the outcomes of interest were related to cardiometabolic disorders (cardiovascular disease, myocardial infarction, stroke, ischaemic heart disease, heart failure, diabetes, and metabolic syndrome); and had no language restriction (if necessary, local scientists fluent in the original language helped with translation). We excluded studies including only pregnant participants; letters, abstracts, systematic reviews, meta-analysis, ecological studies, and conference proceedings; and studies carried out in non-humans.

Two independent reviewers working in pairs (AB-L and OHF, JS, LJ, or SW) screened the titles and abstracts of the initially identified studies to determine if they satisfied the selection criteria. Any disagreements were resolved through consensus or consultation with a third reviewer. Full text articles were retrieved for the selected titles. Reference lists of the retrieved articles were searched for additional publications. We also contacted the authors of the retrieved papers directly for any additional and unpublished studies. The retrieved studies were assessed again by two independent authors (AB-L and OHF) to ensure that they satisfied the inclusion criteria.

Data extraction

We designed a data collection form before the implementation of the search strategy. Two independent reviewers used this form to extract the relevant information from the selected studies (AB-L and OHF). The data collection form included questions on qualitative aspects of the studies (such as date of publication, design, geographical origin and setting, funding source, selection criteria, patient samplings, and location of research group), participant characteristics (such number included in the analysis, age range, mean age, sex, ethnicity, recruitment procedures, residential region, socioeconomic status, comorbidities, and drug treatment), characteristics of the exposure or intervention evaluated (such as type, method used to measure), and information on the reported outcomes (such as measure of disease association, type of outcome, outcome assessment method, type of statistical analysis, adjustment variables).

Quality evaluation

Two independent reviewers (AB-L and OHF) evaluated the quality of the studies included using a modified scoring system that was created on the basis of a recently used system (designed with reference to MOOSE, QUATSO, and STROBE) that allowed a total score of 0–6 points (6 reflecting the highest quality).26 The system allocates one point each for (a) any justification given for the cohort; (b) appropriate inclusion and exclusion criteria were used; (c) diagnosis of cardiometabolic disorders was not solely based on self reporting; (d) participants’ usual chocolate consumption was assessed with a validated tool; (e) adjustments were made for age, sex, body mass index, and smoking status; and (f) any other adjustments were done (such as for physical activity, dietary factors).

Statistical analysis

We evaluated the differences between low and high chocolate consumption on outcomes such as diabetes, incidence of cardiovascular disease, cardiovascular mortality, coronary heart disease, incidence of stroke, and deaths from stroke. We pooled results using a random effects model, and we did tests for heterogeneity and publication bias. Results were expressed as pooled relative risks with 95% confidence intervals.

For each study, we compared the group with highest chocolate consumption against the group with the lowest consumption. Hazard ratios, relative risks, and odds ratios were assumed to approximate the same measure of relative risk. By pooling the study-specific estimates using a random effects model that included between-study heterogeneity (parallel analyses used fixed effect models), we calculated summary relative risks. We carried out a cumulative meta-analysis by outcome in which the pooled estimate of the association reported was updated each time the results of a new study were included. Possible sources of heterogeneity of relative risks were examined using the Cochran-Mantel-Haenszel test for the null hypothesis of no effect (relative risk=1), and the Mantel-Haenszel common relative risk estimate.27 The I² (which quantifies the percentage of variation attributable to heterogeneity) was reported as a measure of consistency across the studies.

Finally, we assessed publication bias by using a funnel plot and Begg’s test to find out whether there was a bias towards publication of studies with positive results among studies with a smaller sample size.28

Subgroup analysis

To test the robustness of our findings, we repeated the meta-analysis by different outcomes (any cardiovascular disease, diabetes, heart failure, and stroke), sex, and types of chocolate (dark, milk, white).

Results

Overall, 4576 references were initially identified: 4563 from electronic databases and 13 from bibliographies and experts (fig 1⇓). Among the databases most of the studies came from Scopus (n=2654) and Embase (n=584). Of the 4576 references, 1221 were duplicates (identified using reference manager and manual checks) and were excluded. After the initial screening of the title and abstract, a further 3302 citations were excluded, leaving 53 articles for retrieval. Full text assessment of these articles resulted in seven eligible studies that were included in our analyses. Of the 46 excluded, 14 did not report levels of chocolate consumption, 14 did not record the effects of chocolate intake on outcomes related to our study, and the remaining 18 were letters, abstracts, or conference proceedings.

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Fig 1 Flow diagram for selection of studies

Characteristics of included studies

Table 1⇓ shows the characteristics of the seven selected studies, which included 114 009 participants. One was a cross sectional study carried out in the United States. The other six were cohort studies carried out in Europe (Germany, Netherlands, and Sweden), Asia (Japan), and North America. Six studies were carried out in the community and one in hospital inpatients. Participants’ age ranged from 25 to 93 years. Although most of the participants were white, one study also included Hispanic and African-American people, and one studied an Asian population. Four studies included men and women, two included only women, and one included only men. In three studies, participants were taking drug treatment, including hormone replacement therapy and drugs for cardiovascular disease (calcium channel blockers, β blockers, angiotensin converting enzyme inhibitors, diuretics, digitalis, nitrates, and aspirin). No study reported the effect of chocolate consumption on metabolic syndrome, and the outcomes reported included myocardial infarction, diabetes, cardiovascular disease, coronary heart disease, heart failure, and stroke (table 2⇓). More than one outcome was measured in four studies, and for these the measure of association for each outcome was included in the analysis.

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Table 1

Characteristics of studies included in meta-analysis of association of chocolate consumption with risk of cardiometabolic disorders

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Table 2

Measures of disease association and adjustments to outcomes in studies of association of chocolate consumption with risk of cardiometabolic disorders

All of the studies reported overall chocolate consumption as the exposure (not reported separately whether dark or white chocolate), and one reported cocoa consumption. Six studies applied food frequency questionnaires to measure the exposure, with some minor modifications from original questionnaires using a single item from the food frequency questionnaire that asked about consumption of chocolate bars, snacks, or pieces. The remaining paper used estimates of chocolate consumption in patient diaries cross checked with dietary history adapted from populations.

Levels of chocolate consumption included the consumption of chocolate bars, chocolate drinks, and chocolate snacks (including confectionery, biscuits, desserts, nutritional supplements, and candy bars). All the studies reported chocolate consumption in a different manner: three categories (never, once a month to less than once a week, and once a week or more); two categories (less than once a week, once a week or more); four categories (never, less than once a month to less than once a week, once a week, and more than once a week); thirds of cacao intake; five categories (none, 1–3/month, 1–2/week, 3–6/week, and >1/day); fourths of chocolate consumption (ranging from 1.7 g/day to 7.5 g/day); and four categories (none, 1–3/month, 1–4/week, and >5/week). Considering the heterogeneity in reporting and measuring chocolate consumption, we decided to use the lowest and highest categories to measure the association of chocolate consumption with cardiometabolic disorders.

The range of time to follow-up for the cohort studies was between eight and 16 years. All studies were funded by public institutions, with no industry funding reported in the acknowledgements sections. Although no study scored the highest level of quality (maximum 6), overall the level was adequate, with six of the seven studies scoring 5 and one scoring 4 (table 1⇑).

Association of chocolate consumption with cardiometabolic disorders by outcome

Of the seven included studies, five (14 875 participants with a high level of chocolate consumption) reported a significant inverse association between chocolate intake and cardiometabolic disorders (table 2, fig 2⇓). Of the 13 measures of association used, 12 (92%) reported a beneficial association of higher chocolate consumption (compared with lowest consumption level) on the prevention of cardiometabolic disorders. The remaining measure was the association of chocolate consumption with heart failure (relative risk 1.23 (95% confidence interval 0.73 to 2.08)). All the measures of association reported were adjusted for age and multiple additional variables, including sex, body mass index, physical activity, smoking, dietary factors (including coffee consumption), and education. Some were also adjusted for drug use (table 2⇑).

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Fig 2 Relative risks for cardiovascular disease, heart failure, and stroke in adults with higher levels of chocolate consumption compared with lower levels

On pooling the retrieved measures of association, we found that high chocolate consumption was associated with about a third decrease in the risk of cardiometabolic disorders—37% in the case of any cardiovascular disease (relative risk 0.63 (95% confidence interval 0.44 to 0.90)) and 29% in the case of stroke prevention (0.71 (0.52 to 0.98)) (see fig 2⇑). No significant association was observed in relation to heart failure (relative risk 0.95 (0.61 to 1.48)).

Only one study evaluated the association between chocolate consumption and diabetes, and it reported a beneficial association in Japanese men and women (hazard ratios 0.65 (0.43 to 0.97) and 0.73 (0.48 to 1.13) respectively).

Publication bias

Funnel plot analysis showed no evidence of significant publication bias (see extra figure on bmj.com).

Discussion

Higher levels of chocolate consumption were associated with a reduction of about a third in the risk of cardiometabolic disorders in our meta-analysis. This beneficial association was significant for any cardiovascular disease (37% reduction), diabetes (31% reduction, based on one publication), and stroke (29% reduction), but no significant association was found in relation to heart failure.

Five of the seven studies included in this meta-analysis reported a significant reduction in the risk of developing cardiometabolic disorders associated with higher levels of chocolate intake (one on cocoa intake), even after adjustment for potential confounders, including age, physical activity, body mass index, smoking status, dietary factors, education, and drug use. Although we did not find any experimental studies (randomised controlled trials) evaluating the effect of chocolate on hard cardiometabolic outcomes, our findings corroborate those of previous meta-analyses of experimental and observational studies in different populations related to risk factors for cardiometabolic disorders. These favourable effects seem mainly mediated by the high content of polyphenols present in cocoa products and probably accrued through increasing the bioavailability of nitric oxide, which subsequently might lead to improvements in endothelial function, reductions in platelet function, and additional beneficial effects on blood pressure, insulin resistance, and blood lipids.

Necessary cautions

Beyond the caution needed in interpretation of data from observational studies, one must also consider other aspects associated with chocolate consumption. For instance, the high energy density of commercially available chocolate (about 2100 kJ (500 kcal)/100 g) means excessive consumption will probably induce weight gain, a risk factor for hypertension, dyslipidaemia, diabetes, and cardiometabolic disorders in general. Hence the high sugar and fat content of commercially available chocolate should be considered, and initiatives to reduce it might permit an improved exposure to the beneficial effect of chocolate. However, the articles included in our analysis did not provide the information needed to evaluate any potential differences between different types of chocolate in the associations with cardiometabolic disorders.

Exploration of heterogeneity

Although our studies included populations with and without prior cardiovascular disease, the small numbers meant we could not evaluate whether the associations found would differ in terms of primary or secondary prevention. Nevertheless, data from previous meta-analyses evaluating the effect of chocolate intake on intermediate factors suggest that the beneficial effects might be similarly beneficial among those with existing cardiovascular disease as it is for those without these conditions. Further studies are required to confirm this.

We found no papers studying the relation between chocolate consumption and the risk of developing metabolic syndrome, and we identified only one study showing the relation between diabetes and chocolate intake (a positive association, especially in men). Although we aimed to evaluate the potential sex differences in the association of chocolate intake with cardiometabolic disorders, the lack of studies reporting stratified results by sex prevented this.

Only two of the studies included evaluated the potential association of chocolate intake with the risk of heart failure. Both studies found no significant effect. This could be related to the nature of the development of heart failure, as it generally occurs towards the end of the spectrum of cardiovascular disorders in terms of natural course and severity of disease. Eventually, this result may need to be examined by further studies.

Strengths and limitations of the review

Previous studies have evaluated the effect of chocolate intake on cardiovascular risk factors and prevention of cardiovascular disorders, but our systematic review is the first attempt to pull together the different existing studies that evaluated the associations of chocolate consumption with cardiometabolic events. One of the reasons for this is that the available literature on this topic is limited and novel, with all studies published in the past four years and with more than half of the included studies published in 2010. We expect further studies will be done to confirm or refute the results of our analyses. Of special importance, experimental evidence will be needed before any level of causality can be inferred from the existing findings, and residual confounding could be considered as a potential explanation for the associations observed.

Considering the limited data available, any conclusions should be cautious. Nevertheless, the current evidence on hard and intermediate outcomes suggests that chocolate might be a viable instrument in the prevention of cardiometabolic disorders if consumed in moderation and if efforts are made to reduce the sugar and fat content of currently available products. Beyond this, considering the acceptability and popularity of chocolate, the applicability of its consumption as a recommendation might suit multiple populations. This would be particularly relevant in developing countries, where most of the cacao plantations and production sites are located (the top producers of cacao include African countries such as the Ivory Coast, Asian countries such as Indonesia, and South American countries such as Brazil) but where the processed form might not be easily available. Chocolate could therefore provide a natural, convenient, and generally welcome prophylactic against the growing epidemics of cardiometabolic disorders in developing countries.

Generalisation of our findings is hampered by the geographical origin of the included studies, as they were mainly carried out in Europe and the United States. Future studies should provide detailed information about different populations or different ethnic groups in other geographical locations and from different socioeconomic levels. Moreover, it is important to assess the effect of different types of chocolate, as well as the measurement and amounts. Given the considerable heterogeneity in the information from the original studies, it was not possible for us to establish a clear dose-response relation between chocolate intake and the risk of cardiometabolic disorders. Furthermore, although most of the included studies adjusted for relevant factors that could confound the association between chocolate consumption and cardiometabolic disorders, the potential confounding effect of these factors might still be prevalent. Chocolate intake is likely to be underestimated by consumers, and may be underestimated to a larger extent by those with a higher body mass index. As people with a higher body mass index are also more likely to have a cardiovascular disease outcome, then the underestimation of their chocolate intake may induce an artificial inverse association between chocolate and risk of cardiovascular disease.

Other factors that might hamper the quality of recording chocolate consumption also need consideration. These include the potential effect of recall bias and the challenges of recording snacks (which might include chocolate) as these are generally under-reported compared with meals.

Conclusions

Cocoa products and chocolate have been consumed and enjoyed by humans for centuries. Although over-consumption can have harmful effects, the existing studies generally agree on a potential beneficial association of chocolate consumption with a lower risk of cardiometabolic disorders. Our findings confirm this, and we found that higher levels of chocolate consumption might be associated with a one third reduction in the risk of developing cardiovascular disease. Corroboration is now required from further studies, especially experimental studies to test causation rather than just association.

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