The skinny on healthy skin


Your skin is your largest organ.  On average, this amounts to about 2 square meters of surface and roughly 3 to 4 kilograms of mass. It helps protect you against potentially harmful substances, extreme temperatures and the Sun’s ultraviolet light. In turn, the skin’s three layers – the epidermis, dermis, and subcutis – depend on you to keep them healthy.  This means taking precautions to avoid the Sun’s damage and meeting your nutritional requirements on a regular basis.

Eat right

Aside from scheduling regular visits to the dermatologist, avoiding direct Sun light for extended periods of time, and wearing Sun screens (hats, long sleeves, umbrellas, lotions), you can make sure you consume a healthy diet which includes vitamins A, B, C, E and omega-3 fatty acids.

Vitamin A

Vitamin A refers to three compounds (retinol, aldehyde, and retinoic acid) called retinoids.  Plants contain carotenoids which are metabolized by the body to form retinoids, the most important of which is B-carotene.  About 50% to 80% of vitamin A in the body is stored in the liver.  The rest is spread out among the lungs, kidneys, adipose tissue and a number of specialized cells throughout the body (1).

Known by most people as being crucial for good vision, vitamin A also plays a role in cell function, growth, development and differentiation (and, thus, is important in keeping our skin healthy), immune function, reproduction and a number of systemic functions, such as gene expression.

The RDA for adults is 700-900 RAE (retinol activity equivalents) which translates into 700-900 mcg of retinol or 8,400-10,800 mcg of B-carotene per day, depending on gender and pregnancy status (1).

  • 1 small sweet potato = 7,374 RAE (about ten times the RDA, or 88,488 mcg of B-carotene)
  • 1 cup raw carrots = 5,553 RAE
  • 1 cup of cooked broccoli = 725 RAE
  • 2 medium tomatoes = 860 RAE
  • 1 cup cooked spinach = 6,882 RAE
  • 1 cup cantaloupe = 1,625 RAE

Given the abundance of carotenoids in the plant world, particularly in the orange and red fruits and vegetables category, it is relatively easy to meet our daily requirements.

Supplementation with vitamin A is contraindicated in the absence of a known deficiency and without medical supervision.  Although readily available in our food supply, vitamin A may be poorly absorbed by some individuals who suffer from pancreatic or liver disease or who lack fat and/or zinc in their diets. On the flip side, vitamin A toxicity is serious business. Regular consumption of vitamin A at 100 times or more the RDA may lead to liver disease, skin disorders, higher incidence of bone fractures (including hip) and lung cancer among smokers (1).

B vitamins

B vitamins, in particular niacin, help keep skin healthy.  Niacin is essential for energy production and metabolism.

Niacin in most plants and grains is covalently bound with peptides and carbohydrates that are not released during digestion. However, alkaline hydrolysis (the addition of water and alkali) makes niacin bioavailable (the Central American tradition of soaking grains in lime water before cooking is, thus, more than just a dietary preference as it serves an important purpose). Niacin is also synthesized from tryptophan (an essential amino acid) with moderate efficiency (60 mg of tryptophan yield 1 mg of niacin) (1).

Ready to eat cereals have the highest niacin content (up to 26 mg per serving, depending on brand).  Mushrooms, peanuts, coffee, breads and pasta all yield enough niacin to meet daily recommendations from just one serving.  Current DRI for adults is anywhere from 2 – 18 mg depending on age and gender (1).

Vitamin C

Vitamin C, aka ascorbic acid, is involved in many electron transport reactions, some of which are involved in collagen synthesis.  Collagen is a fibrous protein found primarily in connective tissue, cartilage, bone, teeth, skin and tendons.  Needless to say, it is important for maintaining healthy skin.  Lucky for us, vitamin C is abundant in most fruits and vegetables, making it relatively easy to meet daily requirements (15 to 120 mg per day depending on age and gender)(1).  In spite of this, vitamin C is one of the most commonly overconsumed supplements in the US and Canada. I can only guess that its popularity rests with the misguided belief that it prevents or cures the common cold.

Too much of this good thing may result in GI disturbances, an increased risk of some cancers (whereas, normal intake has the opposite effect), slight oxaluria, and false-positive urinary glucose test results (1).

Vitamin E

Vitamin E is the most important fat soluble antioxidant in the cell as it protects cell membranes from free radical activity.  It depends on other nutrients and enzymes to do its job, particularly copper, zinc, riboflavin and manganese.

Vitamin E is measured in terms of a-tocopherol equivalents (a-TE) of which adults need about 15 mg per day.

Tocopherols (and tocotrienols) are only synthesized in plants.  The average American, and to a lesser extent, the average Canadian, consumes most of his/her vitamin E in the form of vegetable oil even though healthier sources abound.  One ounce of almonds yields a whopping 7.33 mg (more than three times the amount found in one tablespoon of canola oil)(1).

Omega-3 fatty acids

There are three types of omega-3 fatty acids:  a-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexanoic acid (DHA).  Of these, ALA is an essential fatty acid (EFA), meaning it can not be synthesized by the human body, so, we must get it from food. Humans can desaturate and elongate ALA into EPA and DHA as needed, thus, it is important to include ALA in the diet on a regular basis (1).

The conversion rate of ALA to EPA and DHA is relatively low in persons who consume fish.  However, in vegetarians and vegans, the conversion rate is significantly higher, which explains the similarity of EPA and DHA levels between these groups and their meat-eating cohorts (2).  It is not necessary for vegetarians or vegans to supplement with EPA and DHA as long as they consume a healthy diet that meets their nutritional needs.  In all groups, conversion rates of ALA to EPA and DHA are higher in women (3).

EFA deficiency is rare and occurs primarily among newborns and infants.  Even in developing countries, where food is scarce, EFA deficiency is very low most likely because the most commonly consumed type of fat in such areas is usually vegetable based (vegetable fat is a good source of ALA)(4).

Water

Lastly, stay hydrated inside and out.  Rather than smother your skin with lotion (which can actually draw moisture out of the skin), use a water bottle set on “mist” instead.  Obviously, this may not be the thing to do at the office, but while you’re outdoors or at home, opt for water.  It doesn’t cost anything and it is better for your skin than most other topical applications.

REFERENCES

  1. Mahan LK, Escott-Stump S. Krause’s Food and Nutrition Therapy. MO: Saunders-Elsevier; 2008.
  2. Welch AA, Shakya-Shrestha S, Lentjes MAH, Wareham NJ, Khaw KT. Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the precursor-product ratio of a-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort. Am J Clin Nutr, 2010;92:1040-51.
  3. Burdge GC. Metabolism of a-linolenic acid in humans. Prostaglandins, leukotrienes and essential fatty acids, 2006;75(3):161-8.
  4. The Merck Manual for Health Care Professionals. Available at: http://www.merckmanuals.com/professional/nutritional_disorders/undernutrition/essential_fatty_acid_deficiency.html  Accessed: August 9, 2012.
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