The condition and appearance of our skin is key to our overall health and wellbeing. When skin is in good condition it works hard to protect our bodies from environmental stressors such as irritants, allergens and microbes, regulates temperature and looks and feels smooth, calm, well hydrated and even in colour. There are many factors – both internal and external – that affect skin condition and influence how it looks and feels. For example, because of its compromised skin barrier, hypersensitive skin is more prone to irritation than well-balanced skin. Some factors we cannot influence, but many we can. Careful skincare can protect skin and keep it looking younger for longer.
Internal (endogenous) factors
The internal factors that influence skin include genetics, hormones and specific conditions such as diabetes.
A person’s genetics determine their skin type (normal, dry, oily or combination) and affect their overall skin condition.
Genetics and biological skin ageing
Genetics also determine the biological ageing of skin which is characterised by:
- A decline in cell regeneration and renewal.
- Reduced sebaceous and sweat gland secretions.
- Degeneration of the connective tissue so that skin is less able to bind in water and loses firmness.
- Degeneration of elastic fibres which results in reduced skin elasticity.
Biological skin ageing is not be confused with premature skin ageing which is caused by external factors and can be influenced.
Internal factors that affect skin: hormones
A predisposition to skin diseases such as Atopic Dermatitis, Psoriasis and Ichthyosis is also decided by genetics. For example, those born with a genetic Filaggrin (a protein found in skin) deficiency have skin with a weaker barrier function and are prone to sensitive skin and Atopic Dermatitis. With such a predisposition, skin can be triggered more easily by stress and exacerbated by external influences. Therefore it’s crucial to have a proper skin care regime in place. Read more in dry skin and Atopic Dermatitis.
There are also some diseases – such as diabetes and renal failure – that can impact on skin condition.
Hormones, and changes in their levels, can have a significant impact on skin:
- Hormonal changes can trigger the acne of puberty.
- During pregnancy, hormones can encourage the increased production of melanin and a form of hyperpigmentation known as melasma.
- Female oestrogen levels decline as part of the biological ageing process and especially after the menopause. Oestrogen has a beneficial effect on the moisture balance of skin and its decline leads to structural changes and the age-related atrophy of skin.
External (exogenous) factors
There are many external factors that influence skin condition. When skin’s natural balance is compromised, it is less able to work as a protective barrier and prone to sensitivity. The external factors that influence skin health are determined by the environment around us, our overall health and the lifestyle choices we make.
Climate and environment
Free radicals are aggressive molecules responsible for the oxidation process in body tissues that results in cell damage. Healthy skin contains antioxidants that protect it by neutralising the free radicals.
In the epidermis, these free radicals are mainly generated by UV rays. In normal conditions, and with limited exposure to UV, skin’s protective mechanisms are more or less able to cope. IIf, however, exposure is sustained, skin’s protective mechanisms are weakened and it is less effective as a protective barrier. Under these conditions, skin becomes sensitive and is prone to disease. Years of unprotected sun exposure leads to chronic light-induced damage and, with it, premature skin ageing. UV rays can be particularly harmful to Rosacea-prone skin as its compromised skin barrier can be easily penetrated and the underlying hyper-reactive nerve fibres aggravated.
Read more about the effects of sun exposure and how to protect skin in sun.
Extreme temperatures, and the speed of change between them, impact on skin health.
In cold conditions skin reacts by narrowing the blood vessels to protect the body from losing too much heat. Sustained cold temperatures reduce sebaceous gland secretion and cause skin to dry out. Read more in dry skin.
In hot and humid conditions (for example tropical countries or a sauna) sweat glands produce more sweat, leaving the skin moist and shiny and, in some cases, prone to acne.
Low humidity, as found in aeroplane cabins and even caused by central heating, can cause skin to become dehydrated and lead to increased sensitivity.
Some skin conditions, for example rosacea, can also be triggered by hot temperatures. This is one of the reasons why it is recommended to use warm rather than hot water for facial cleansing, hand washing and bathing.
Skin is naturally mildly acidic, with a pH of between 4.7 and 5.75. Aggressive cleansers (such as sodium lauryl sulphate and moisturising products with an alkaline pH) overtax skin’s natural neutralising capability, damage cell structure and impair the barrier function of the outermost layer of the epidermis. As a result, skin can dry out and become sensitive or even hypersensitive.
When skin is sensitive it is susceptible to skin infections and flare-ups of diseases such as Atopic Dermatitis or Rosacea. Sensitive skin (which is characterised by a weakened protective barrier) and hypersensitive skin (which additionally has hyperactive nerve fibres) are both particularly prone to the drying and damaging effects of harsh products.
Certain chemical peels can have a similar affect and it is important to consult a doctor or dermatologist to check that a particular procedure is suitable for your skin.
Some people are particularly affected by aggressive products:
- Small children and the elderly: Young and old skin is less resistant because sebaceous gland activity is either not yet fully developed or is on the decline. Read more in skin in different ages.
- Those exposed to chemicals in the workplace: Professionals such as hairdressers, masons and industrial workers are in regular contact with detergents, solvents, lacquers and paints, all substances that are harmful to the skin.
Washing too frequently
Showering or bathing too frequently, for too long and with water that is too hot leads to a loss of skin’s natural moisturising factors (known as NMFs) and surface lipids. Skin dries out and becomes rough. The pH of healthy skin is mildly acidic, and frequent washing with tap water - that ranges from neutral to mildly alkaline - can impact on skin’s natural balance and impair its protective barrier function. Read more about caring for skin on the body and a daily skincare routine for the face.
External factors that affect skin: diet
A balanced diet will help to keep skin healthy. Research on the best foods for healthy skin suggest:
- Fruits, vegetables, whole grains and lean proteins (fish instead of meat) are all good for skin.
- A diet rich in vitamin C and low in fats and carbohydrates may promote younger looking skin.
- Antioxidant-rich foods seem to have protective benefits. These include: yellow and orange fruits and vegetables (e.g. carrots and apricots), blueberries, green leafy vegetables (e.g. spinach), tomatoes, peas, beans and lentils, fish (especially salmon), nuts.
- Diets that exclude a particular food group and its nutritional value are not, on the whole, good for skin health. It is, however, advisable to limit the intake of sweets and dairy. It is also important to drink plenty of water, especially for elderly people.
There is no clear association between diet and the causes of acne.
External factors that affect skin: medication
Certain medicines (e.g. chemotherapy, diuretics, laxatives and the lipid-lowering drugs sometimes taken to treat cardiovascular conditions) and medical procedures (e.g. radiotherapy and dialysis) can make skin more sensitive and prone to dryness.
Healthy lifestyle choices can help to delay the natural ageing process and prevent skin problems:
Uncontrolled stress can make skin more sensitive and trigger problems including acne. Stress needs managing: reducing workload, making time for leisure activities and relaxation techniques can help.
Regular exercise has a positive impact on skin health as well as overall fitness.
A good night’s sleep gives the whole being a chance to regenerate and thus contributes the renewal of skin.
Tobacco smoke is a major source of skin damaging free radicals. Smoking makes skin look older and contributes to wrinkles by:
- Narrowing the tiny blood vessels in the inner layers of skin. This decreases blood flow and depletes skin of oxygen and nutrients such as Vitamin A.
- Damaging collagen and elastin: the fibres that give skin its strength and elasticity.