Reasons of acne

Acne develops as a result of blockages in follicles. Hyperkeratinization and formation of a plug of keratin and sebum is the earliest change. Enlargement of sebaceous glands and an increase in sebum production occur with increased androgen production at adrenarche. The microcomedo may enlarge to form an open comedone or closed comedone. Comedones are the direct result of sebaceous glands' becoming clogged with sebum, a naturally occurring oil, and dead skin cells. It can be summarized as
1)      Each pore is an opening to a follicle, which contains a hair and an oil gland. These oil glands help lubricate the skin and help remove old skin cells.

2)      When glands produce too much oil, the pores can become blocked. Dirt, debris, bacteria, and inflammatory cells build up. The blockage is called a plug or comedone.3)      The top of the plug may be white or dark.4)      If the plug breaks open, the material inside causes swelling and red bumps to form.5)      If the inflammation is deep in your skin, the pimples may enlarge to form firm, painful cysts.

 In these conditions, the naturally occurring largely commensal bacterium Propionibacterium acnes can cause inflammation, leading to inflammatory lesions in the dermis around the microcomedo or comedone, which results in redness and may result in scarring or hyperpigmentation.
Acne tends to run in families and can be triggered by:

a)       Hormonal changes related to menstrual periods, pregnancy, birth control pills, or stressb)       Greasy or oily cosmetic and hair productsc)       Certain drugs (such as steroids, testosterone, estrogen, and phenytoin)d)       High levels of humidity and sweating

Hormones

Hormonal activity, such as menstrual cycles and puberty, may contribute to the formation of acne. During puberty, an increase in male sex hormones called androgens causes the follicular glands to grow larger and make more sebum.

Hormones are responsible for the maturation of the oil glands in our skin. This is why children do not experience acne. Several hormones have been linked to acne: the androgens testosterone, dihydrotestosterone and insulin.

There are several times in our lives when our hormones can become unbalanced and wreak havoc, including puberty, pregnancy, menopause, and, well, any other time they feel like it. More specifically, acne may be precipitated by androgens, male hormones present in both men and women.

Hormonal acne is seen mostly in women due to the natural cycles a woman goes through, such as menstruation, pregnancy and menopause True acne vulgaris in adult women may be a feature of an underlying condition such as pregnancy and disorders such as polycystic ovary syndrome or the rare Cushing's syndrome. Menopause-associated acne occurs as production of the natural anti-acne ovarian hormone estradiol fails at menopause.

Genes and Acne

The investigators, at the Medical College of Georgia, Augusta, Georgia, Cancer Research U.K., and St Thomas' Hospital, in London, England, noted that although clinical experience indicated that acne appeared to run in families, few studies have looked into its genetic basis.

  Genetic factors far outweigh environmental influences on the development of acne in women, investigators report.Family history of acne was also significantly associated with an increased risk

  The tendency to develop acne runs in families. For example, school aged boys with acne often have other members in their family with acne as well. A family history of acne is associated with an earlier occurrence of acne and an increased number of retentional acne lesions.

Psychological

While the connection between acne and stress has been debated, scientific research indicates that "increased acne severity" is "significantly associated with increased stress levels. The National Institutes of Health (USA) list stress as a factor that "can cause an acne flare. A study of adolescents in Singapore "observed a statistically significant positive correlation between stress levels and severity of acne.It is also not clear whether acne causes stress and thus perpetuates itself to some extent.

FoodDiet has a direct effect on our body's insulin levels. Insulin is our master hormone and affects all of our other hormones, including our androgens. Scientists heavily suspect that hormonal fluctuations, particularly in our androgen levels, can result in acne flare ups. Insulin also affects growth hormone and a host of other hormones which may be related to acne formation on a cellular level. It is hypothesized, yet unproven, that a diet which causes insulin spikes may affect development of acne.

Fatty foods create blood sugar instability by making the levels rush up and then plummet just as fast, leading to severe hormonal reactions and consequently, acne. Fatty foods also slow down the flow of nutrients and to your body cells which aggravates acne.
A high glycemic load diet and cow's milk have been associated with worsening acne. The digestive system lacks the required enzymes to break down milk, and the immune system creates a reaction that can lead to oxidative stress and inflammation, therefore acne. Chocolate-chip cookies made with cottonseed and/or soybean oil, the problem ingredient being the cottonseed oil or soybean oil, not the chocolate.
The right diet may also be related to acne in positive ways. Eating a low glycemic diet rich in veggies, fruit, seafood, and grass-fed meat can help stabilize insulin levels, which theoretically may have an impact. Also, ingesting Omega-3 fats has been shown to be a powerful anti-inflammatory agent in our body. Since a big part of acne is inflammation, it makes theoretical sense that eating an anti-inflammatory diet would help.
Caffeine has been proven to be an acne trigger by making the adrenalin glands secretes hormones that give you the buzz. These hormones, essentially stress your system terribly, affecting not just your skin but additionally your health.
Stress

Stress is any taxing of our emotional or physical being. Many people view stress as just an emotional issue, but when we're speaking about acne, it is best to include undue physical strain in our definition since both can come into play.Stress causes an inflammatory response in the body and can cause the walls of these pores to break. When this happens, the body responds with redness around the broken pore, and an influx of pus.

Also, when we experience stress, our adrenal gland goes into overdrive. Androgens, which this gland produces, increase. Higher androgen levels can lead to more acne. This is especially true in women, who produce a much larger percentage of their androgens in the adrenal gland than men. This may explain why stress seems to affect women more than men when it comes to acne.
Bacteria
A bacterium, known as Propionibacterium acnes, is a normal inhabitant of the skin. It is the anaerobic bacterium that causes acne. In vitro, resistance of P. acnes to commonly used antibiotics has been increasing. It uses sebum as a nutrient for growth, therefore increases in follicles during puberty. People with acne have more Propionibacterium acnes in their follicles than people without acne.
The presence of bacteria attracts white blood cells to the follicle. These white blood cells produce an enzyme that damages the wall of the follicle, allowing the contents of the follicle to enter the dermis. This process causes an inflammatory response seen as papules, pustules, and nodules. The bacteria also cause the formation of free fatty acids, which are irritants, increasing the inflammatory process in the follicle.