November,
2006
Today’s
CPE: Nurturing Skin
From the Inside Out
By Pamela Stuppy, MS, RD, LD
Today’s Dietitian
Vol. 8 No. 11 P. 12
On the surface, a person’s skin often
defines his or her appearance. But skin also serves a more important
purpose: it can indicate what may be occurring inside the body.
Like the saying “the eyes are the windows to the soul,”
the skin is a window to inner health. Nutrition plays a vital
role in protecting skin and addressing the health issues that
it reflects.
Recent outbreaks of antibiotic-resistant infections
have focused attention on another vital function of the body’s
largest organ: immunity. The body has many full-time defenses
against harmful organisms—so-called “nonself”
organisms—that seek to enter the body. These defense mechanisms,
the body’s first line of defense, do not have to be alerted
to combat an invader, although they may increase their activity
in response to a foreign organism. They have limited ability
to distinguish one invader from another. Everything outside
the body is nonself; everything inside is self. We call this
nonspecific resistance. The skin, tear glands, kidneys, gastrointestinal
(GI) tract, and mucous membranes are all nonspecific resistors.
The skin not only presents a physical barrier
to nonself organisms; if breached, it also mounts a response
to invaders. During this inflammation response, cells called
phagocytes in the blood and lymph migrate to the site of bacterial,
fungal, and protozoal invasions to surround and engulf invading
microbes.
The inflammation response can also be destructive
if it persists over a period of time. In destroying foreign
particles, phagocytic cells release substances that can damage
surrounding tissues. The characteristic redness and heat of
an inflammation reflect the irritating effects of these chemicals.
Continual inflammation, such as arthritis, can permanently damage
the tissue where the inflammation is located—in the case
of arthritis, the joints. Usually, however, the inflammation
is short-lived. Although painful, unsightly, and distressing,
inflammation means the immune system is working.
Since the skin is the body’s largest immune
system organ, and because it performs other functions such as
maintaining hydration and regulating body temperature, we need
to know how to keep it healthy. As a nice side benefit, healthy
skin is attractive skin!
The skin is composed of two layers: the dermis
(the thicker lower layer) and the epidermis (the upper surface),
separated by a collagen-rich membrane that controls substances
that pass between the layers.
The epidermis protects against abrasion, impact,
pathogens, environmental chemicals, and ultraviolet (UV) light.
A specialized type of cell, the melanocyte, contains pigments
that reduce the risk of UV damage. The dermis provides mechanical
support and flexibility and it is comprised of collagen bundles
and elastic fibers. Impaired formation of the dermis causes
fragile skin that can tear. The dermis may be highly vascular
but can undergo age-related thinning and increased susceptibility
to damage.
Under normal circumstances, cell division occurs
in the basal layer below the epidermis. The cells mature and
travel along a calcium gradient toward the skin surface, losing
their ability to proliferate. During skin injury, however, cell
division occurs at deeper levels.
Numerous factors negatively affect skin, including
exposure to sun or a dry environment, inadequate fluids, smoking,
poor eating habits, pollution or other contact substances, allergens,
hormonal changes, a sedentary lifestyle, stress, aging, and
genetics.
Nutrition plays a vital role in skin maintenance
and health. Dermal tissue depends on vitamin C and the amino
acids proline and lysine to support collagen. Iron, zinc, and
calcium act as cofactors for needed enzymes. Melanin, the chemical
component of melanocytes, requires copper, zinc, iron, cobalt,
nickel, and the amino acid tyrosine.
Nutrient deficiencies can be caused by inadequate
intake, inefficient digestion/absorption/transport, interference
by fiber or other binding substances, or certain medications.
Examples include deficiencies of vitamin A, some B vitamins,
vitamin C, biotin, essential fatty acids (EFAs), zinc, and manganese.
In some cases, an actual nutrient deficiency
is required before a symptom is apparent. However, even subclinical
deficiencies produce a noted change. Some borderline deficiencies
become true deficiencies under conditions of physiological stress—surgery,
for instance.
The skin puts on quite a show when its perimeter
is breached. Some of the activities include repair processes,
activation and interaction of hormones, growth factors, cytokines,
chemotactic factors, and an environment that supports cell division,
cell migration, and differentiation.1 The objectives in wound
healing are to heal the wound in as short a time as possible
to achieve maximum repair while minimizing pain, discomfort,
and scarring. The scar should be fine and flexible with high
tensile strength.
There are four main phases of wound repair:
clearing of dead tissue and foreign matter, the inflammatory
phase, the proliferation phase, and the remodeling or reorganization
phase.2 Chronic wounds that do not heal get caught in one of
these phases.
Essential nutrients needed for skin repair include
protein, some specific amino acids (proline, hydroxyproline,
cysteine, cystine, methionine, tyrosine, arginine, glycine),
glucose, lipids (linoleic and linolenic acids, arachidonic acid,
eicosanoids, other fatty acids), vitamins (A, B complex, C,
D, E, K), minerals (sodium, potassium, copper, calcium, iron,
magnesium, manganese, zinc, selenium, nickel, chromium), and
water.3
Inadequate amounts of protein and amino acids
cause healing that results in thin, fragile skin with low tensile
strength. Nitrogen balance at the site of healing is crucial.
Protein and certain amino acids are used for RNA and DNA synthesis,
formation of collagen and elastic tissue, immune system functions,
growth, and keratinization of the epidermis. They are part of
all four healing phases. Arginine and glutamine appear particularly
beneficial.
Glucose in adequate amounts is needed for the
enhanced energy needs of tissue repair. Excessive glucose, experienced
in people with unregulated diabetes, can increase the risk of
infection. Other mechanisms related to poor wound healing in
people with diabetes include poor circulation, osmotic changes,
interference with vitamin A and zinc metabolism, growth factor
imbalances, acidosis, and inflammatory changes.3 Improved glucose
control through appropriate diet, exercise, and medications
will improve wound outcomes.
Fats and fatty acids help with cell membrane
synthesis, are a component of the epidermal barrier layer, are
involved in inflammatory reactions, and assist with the synthesis
of the intercellular matrix. Polyunsaturated and monounsaturated
fatty acids appear helpful in wound healing and the inflammatory
response.
Vitamin A helps with epidermal cell proliferation
and maturation. But excessive levels of this vitamin can cause
unwanted side effects. During wound healing, it promotes the
early inflammatory phase and infiltration of macrophages, monocytes,
and fibroblasts, which lead to increased vascularization of
tissue and collagen formation.
Vitamins and Minerals
The B vitamins have varied roles in general health and wound
healing and therefore cannot be ignored. However, other micronutrients
have more specific roles in skin health.
Vitamin C is involved in many enzyme systems in the skin’s
upper layers. It is related to calcium metabolism and the calcium/magnesium
balance. (The calcium gradient is a crucial part of the epidermal
layer.) As in other parts of the body, vitamin C is involved
in collagen production, which gives skin and repaired wounds
their tensile strength. Low intakes have been shown to negatively
affect uptake and metabolism of certain essential amino acids
related to collagen production and enzyme activation. Additionally,
vitamin C acts as an antioxidant and assists the immune system.
The skin is the site of vitamin D synthesis
and storage. The effectiveness of the skin’s vitamin D
production deteriorates with age and individuals with darker
skin may also have lower production.
Because of vitamin K’s role in blood clotting,
a deficiency results in poor wound repair and an increased risk
of infection. It is especially important during the initial
phase of wound healing.
In past years, topical products containing vitamin
E have been marketed. Evidence for its role in wound healing
is inconclusive, although it should be included as part of a
balanced diet.
Minerals act as structural components of skin
cells and intracellular fluids. They also serve as cofactors
of metalloenzyme systems involved in numerous reactions as electrolytes
and assist in the function of epidermal cells, skin glands,
and cell membrane exchange. Calcium is involved in normal skin
cell turnover but appears to increase rapidly at wounding and
remains elevated until the final phase of healing.
Zinc functions in numerous enzyme systems but
is most highly concentrated wherever cells are undergoing proliferation,
such as during wound healing. The skin, particularly the epidermal
layer, is an area of high cell turnover, especially during wound
repair. As with calcium, zinc levels rise at wounding and remain
elevated. Zinc can be taken systemically or used topically.
Copper is also involved as a cofactor in enzyme
systems. A deficiency causes skin thinning because of impaired
collagen and elastic tissue synthesis and can impair the immune
response and lower resistance to infection. The effects on collagen
and elastic tissue mean reduced tensile strength for wounds.
Copper also plays a direct role in angiogenesis, the formation
of new blood vessels.
Iron is required for normal skin and during
wound healing. It is often a reflection of an individual’s
overall nutritional status. Iron deficiency can interfere with
oxygen transport to the wound site, which impairs healing. Iron
also plays a role in the function of neutrophils and macrophages,
which reduce infection at the wound site.
Hydration and Wound
Healing
Adequate hydration contributes to soft, smooth skin. Hydration,
with adequate oxygen, allows more efficient cell proliferation
and migration. It is maintained by amino acids and by sebum
(secreted by the sebaceous glands) and other epidermal lipids
by providing a protective lipid layer. Electrolytes assist with
water balance. Dehydration causes increased hardening of skin
cells. Wounds that dry out are at greater risk for infection
and can become cracked and painful.
Skin pH plays a role in protection from pathogens.4
It is affected by skin lipids and amino acids. Unsaturated fatty
acids contribute to skin acidity and prevent bacteria growth
on the skin. Men tend to have lower pH levels and better hydration
than women.
Older persons may be at increased risk for poor
wound healing—and poor skin health in general—due
to inadequate consumption of nutrients or fluids, impaired absorption
and transport of nutrients due to physiological changes or medications,
and/or reduced blood flow due to sedentary behavior. Their immune
systems are generally less efficient, which puts them at greater
risk of infection.
Dietitians can address issues such as decreased
appetite, dependency on assistance with feeding, impaired cognition
or communication, poor positioning, GI issues, side effects
of medications, deliberate fluid restriction due to concerns
about incontinence, dysphasia, psychological issues, monotonous
diet, and higher nutrient requirements.
Skin Aging
Aging can mean not only normal biological aging, including hormonal
changes, but also exacerbation by UV radiation and environmental
pollution, stress, malnutrition, vascular disturbances, smoking,
and alcohol/drug abuse. It is characterized by tissue atrophy,
coarseness, wrinkling, drying, changes in pigmentation or surface
blood vessels, reduced elasticity, and premalignant/malignant
neoplasms.
As the skin ages, the dermal tissue diminishes
because of changes in the structure and composition of collagen
and elastin. One consequence is reduced skin elasticity. Since
total body protein decreases with age, dietary intake of high
biological value protein is important for skin maintenance.
Protein deficiency can promote skin fragility.
Additionally, there is a lower water content
and sweat/sebaceous gland production decreases due to hormonal
changes. Lipids, fluid intake, and the epidermis’ ability
to conserve water are critical in water balance. Replacement
of the epidermal lipid barrier is less efficient with aging.
Approximately 7% of total skin thickness is lost every 10 years.5
Also, the internal protective systems in the skin tend to become
dramatically less efficient with aging.
Antioxidants
In many cases, skin aging is due to the activity of free radicals,
which is affected by dietary antioxidant intake, nutrients related
to cofactors/coenzymes required for endogenous antioxidants,
stress, and environmental and lifestyle factors.
Skin integrity can be improved by an overall
healthy diet, adequate fluids, regular exercise to improve circulation,
and intake of antioxidants (carotenoids, tocopherols, ascorbate,
polyphenols/flavanoids), preferably from foods. Flavanoids can
assist with reducing collagen breakdown in inflamed skin, as
well as reducing damage from the sun. The diet should include
a variety of plant-based foods and adequate intake of EFAs and
omega-3 fatty acids. Examples of good polyphenol/flavanoid sources
are green tea, milk thistle, and grape seed extract.
The body has numerous endogenous antioxidant
systems that require specific mineral cofactors (such as zinc)
that need to be consumed in the diet. These and the dietary
antioxidants function to squelch free radicals. Reducing UV
radiation exposure and quitting smoking also slow the aging
process. (UVA rays damage the dermal layer of the skin; UVB
rays damage the epidermis.)
Recent research suggests a relationship between
sun damage, free radical damage, and skin carcinogenesis. First,
reactive oxygen species are generated by excessive UV skin exposure.
Second, UV exposure reduces the effectiveness of the natural
antioxidant defense system. Third, free radicals are involved
in all aspects of carcinogenesis. Fourth, higher intakes of
antioxidants can reduce carcinogenesis. And fifth, conditions
that increase free radical production also increase photocarcinogenesis.
Some micronutrients, similar to antioxidants,
can act as UV absorbers. Persons with higher intakes of vitamin
D and carotenoids (alpha- and beta-, cryptoxanthin, lutein,
lycopene) and lower intakes of alcohol appear to have reduced
melanoma risk. Omega-3 fatty acids, carotenoids, and other antioxidants
appear to be photoprotective and can be used prophylactically.6
Antioxidant properties are also exhibited by genistein, an isoflavone
in soybeans, with regard to reduced photodamage. UV exposure
can also reduce immune system function, which can be countered
by a healthy diet.
Women’s
Skin Issues
Women generally take more interest in their skin care than men.
Although this may relate to societal expectations, skin issues
have a physiological basis. Several gender-linked factors make
women more vulnerable to skin problems.
When estrogen levels drop at menopause, skin
changes occur. Some women who do not choose hormone replacement
therapy may use weaker plant estrogens found in soy products
or natural progesterones in response to these changes. The isoflavones
in soy provide low levels of estrogenic activity with less risk
for the negative side effects of synthetic hormones.
PCOS and Skin
Polycystic ovary syndrome (PCOS), a disorder affecting as many
as 10 million women, may cause numerous skin problems.7 Some
of these are due to elevated insulin while others are related
to high serum androgens (male hormones).
Acne, which is more obvious in adult women with
PCOS, is caused by increased sebum (a combination of skin oils
and old tissue that clogs pores), prompted by elevated androgens.
This provides a feeding ground for bacteria with resulting inflammation.
Acanthosis nigricans is velvety, raised, pigmented
skin that can appear on the back of the neck, armpit area, or
beneath the breasts of women with sustained elevated serum insulin
levels. Because of the relationship with insulin resistance,
these women are at increased risk of metabolic syndrome, which
is another name for a combination of diabetes, hyperlipidemia,
and hypertension.
Skin tags may be another result of PCOS. These
are varied in appearance. They may be raised or stalked, smooth
or rough, and flesh-colored or darker than surrounding skin.
Common locations are the eyelids, neck, armpits, upper chest,
and groin. They appear to be benign so they do not require removal.
Besides these skin symptoms, irregular menstrual
cycles or failed attempts at conception may be the only clues
that a woman has PCOS. It is highly underdiagnosed. All of these
skin presentations of PCOS can be improved by resolving the
underlying issues of PCOS: insulin resistance, obesity or central
adiposity, and elevated androgens. Exercise is a key component
of treatment. If the woman is overweight, weight loss will improve
both insulin resistance and androgen levels.
The PCOS diet should be similar to one recommended
for people with type 2 diabetes: complex carbohydrates paired
with protein and/or high-fiber foods spread evenly throughout
the day, limited refined carbohydrates, and moderation in fat
intake with unsaturated fats preferred to saturated fats. Also
similar to type 2 diabetes, metformin has been used with positive
results to reduce insulin resistance. Antiandrogens and/or oral
contraceptives may also be used to reach better hormonal balance.
Dermatitis
Dermatitis is defined as an inflammation of the skin caused
by internal or external factors, including food allergies or
sensitivities or contact with an irritating substance. A common
symptom is eczema, which consists of any combination of redness,
papules, vesicles, pustules, scales, crusts, or scabs. Various
forms exist. One form in particular, dermatitis herpetiformis
(DH), is of special interest to dietitians.
DH is an intensely itchy, blistering bilateral
skin rash related to gluten sensitivity. The most common sites
include the knees, elbows, scalp, sacral or shoulder area, and
buttocks. Incidence can occur in the teenage years or in the
second or third decades of life. Males are twice as likely to
have DH than females and it is more common in Caucasians than
African Americans or Asians.
DH occurs in a small number of persons diagnosed
with celiac disease. Interestingly, despite the relationship
to celiac disease, many persons with DH do not exhibit overt
intestinal symptoms. With DH, serum indicators of gluten sensitivity
are positive and a biopsy will usually indicate damage to the
intestinal mucosa. Affected and unaffected skin areas may show
elevated levels of immunoglobulin A (IgA) due to the gluten
reaction. A skin biopsy can be used to diagnose DH.
A gluten-free diet will begin to reverse DH
symptoms, but full recovery can take well over six months. Since
it is an autoimmune response similar to the intestinal manifestations
of celiac disease, the potential for return of symptoms is lifelong.
Fortunately, there are increasing resources
for guidance in following a gluten-free diet.8 There are also
a number of manufacturers trying to provide a wider range of
gluten-free products. Current food labeling requires manufacturers
to indicate whether the product contains wheat but not other
sources of gluten.
Another form of dermatitis, atopic dermatitis,
has an allergic component that may involve intestinal flora
and thus (indirectly, at least) diet and supplementation. Atopic
dermatitis is a form of itching dermatitis that may be due to
an allergic reaction but may also involve hereditary or psychological
factors. It is seen in a growing number of infants, children,
and adults. Atopy is a personal or familial tendency to produce
immunoglobulin E (IgE) antibodies in response to allergens.
The result can be a form of dermatitis/eczema. Allergies are
a hypersensitivity response that can be either IgE- or non–IgE-mediated.
Although the etiology is still uncertain, increased
permeability of the intestinal lining may account for some of
the allergic responses. Increasing the number of certain beneficial
bacteria in the intestinal tract may improve the integrity of
the lining by allowing more selective passage of substances
into the bloodstream. This can be done by consuming food products
such as yogurt or supplements containing active cultures (probiotics).
Improving this intestinal barrier may then reduce the number
of allergens that enter the body.
Studies on infants indicate that probiotic formulas
have been useful in treating atopic dermatitis cases.9 Certain
strains of lactobacillus and bifidobacterium have reduced the
incidence of eczema in infants. Because the opportunity for
colonization of the intestinal tract in infants may be limited,
supplementation of beneficial bacteria appears to hasten the
maturity of this colonization. It’s recommended to match
the type of bacteria in the supplement to the bacteria that
would normally reside in the infant’s intestinal tract.
Additionally with atopic dermatitis, there appears
to be a reduced inflammatory response, down-regulation of the
pro-inflammatory cytokines, and improvement of the immunological
defense barrier (IgA) of the intestine with the use of probiotics.
Enzymes from some probiotic bacteria may also directly degrade
allergens, rendering them nonallergic.
Since an underlying allergy may be the cause
of atopic dermatitis, researchers have suggested that certain
fatty acids and antioxidants may be protective against the development
of allergies and help lower the inflammatory response. An abnormality
seen in atopic patients has been an imbalance between omega-6
and omega-3 fatty acids. Metabolites of arachidonic acid can
cause inflammatory skin reactions such as psoriasis and atopic
dermatitis. Improving this balance by increasing the intake
of omega-3 fatty acids appears helpful. Some cases of atopic
dermatitis have shown improvement with the use of gamma-linolenic
acid (found in evening primrose oil).
Antioxidants such as ascorbic acid, beta-carotene,
alpha-tocopherol, selenium, and zinc can counter the oxidative
stress caused by inflammation in atopic disease. A maternal
diet high in vitamin C during breast-feeding may reduce the
risk of atopy in high-risk infants. Prebiotics, such as nondigestible
oligosaccharides, added to the diet to enhance the growth environment
for probiotic bacteria may also be recommended.
Food allergies are on the rise and some people
with allergies are more likely to present with dermatitis. As
noted in the Food Allergy Survival Guide, these include allergies
to certain fruits (berries, citrus), wheat and other glutenous
grains, azo dyes, cow’s milk, soy, sulfates, eggs, tree
nuts, fish, peanuts, benzoates, and shellfish.10
Avoidance of the allergen is the best treatment
for food allergies. A hypoallergenic multivitamin can be used
when needed. Intake of omega-3 fatty acids and EFAs can reduce
the level of inflammation and dryness. With severe allergic
pruritus, conjugated linoleic acid may be helpful. Breast-feeding
is partially protective against dermatitis if no other foods
or beverages are consumed. Delaying the introduction of potential
allergens to infants is a good idea if there is a family history
of food allergies.
Psoriasis
Psoriasis is another autoimmune skin disorder that may have
dietary implications. Many autoimmune diseases benefit from
the use of omega-3 fatty acids. Those from fish oils (eicosapentaenoic
acid and docosahexaenoic acid) are more biologically potent
than alpha-linolenic acid found in oils such as flaxseed. Vitamin
D and exposure to UV rays have been used as treatment for psoriasis
with varying results.
Some studies suggest that a percentage of persons
with psoriasis also have celiac disease or at least respond
positively to a gluten-free diet. Upon examination, they have
evidence of IgA and/or immunoglobulin G antibodies to gliadin.
The gluten-free diet promotes lower levels of tissue transglutaminase
and decreases in the psoriasis-area severity index. When a normal
diet was resumed, the psoriasis deteriorated. Patients with
elevated antigliadin antibodies also tended to have more severe
disease activity.
EFA deficiency can exist in numerous situations.
The most obvious is in protein-calorie malnutrition. Other causes
may include low EFA intake, poor lipid digestion, problems with
absorption or transport, desaturation, or beta-oxidation/peroxidation.
Other deficiencies (eg, micronutrients) may
contribute to low EFA bioavailability and metabolism. EFA deficiencies
can cause a scaly skin disorder, changes in epidermal hyperproliferation,
and excessive epidermal water loss; contribute to impaired resistance
to infections; and cause problems with growth/development.
In normal skin, dermal integrity depends on
omega-6 fatty acids such as linoleic acid. They are specifically
involved in the cohesion of the stratum corneum and prevention
of transepidermal fluid loss. They are part of the lipid by-layers
that fill the intercellular spaces in the upper part of the
epidermis. They also allow for flexibility of the cell membranes.
As the population ages, concern for skin health
and vitality will increase. The evidence is clear that an overall
healthy diet not only improves skin integrity and vitality but
reduces the risk of numerous skin-related conditions.
— Pamela Stuppy, MS, RD, LD, has a
nutrition consulting business with offices in York, Me., and
Newington, N.H. She is the dietitian for Phillips Exeter Academy
in New Hampshire and the consulting dietitian for Oakhurst Dairy
in Maine.
References
1. Lansdown AB. Nutrition 1: A vital consideration in the management
of skin wounds. Br J Nurs. 2004;13(19):S22-S28.
2. MacKay D, Miller AL. Nutritional support
for wound healing. Altern Med Rev. 2003;8(4):359-377.
3. Lansdown AB. Nutrition 2: A vital consideration
in the management of skin wounds. Br J Nurs. 2004;13(20):1199-1210.
4. Boelsma E, van de Vijver LP, Goldbahm RA,
et al. Human skin condition and its associations with nutrient
concentrations in serum and diet. Am J Clin Nutr. 2003;77(2):348-355.
5. Biesalski HK, Berneburg M, Grune T, et al.
Oxidative and premature skin aging. Exper Dermatology. 2003;12(Suppl
3):3-15.
6. Sies H, Stahl W. Nutritional protection against
skin damage from sunlight. Ann Rev Nutr. 2004;24:173-200.
7. Thatcher SS. PCOS: The Hidden Epidemic. Indianapolis:
Perspective Press; 2000.
8. Case S. Gluten-Free Diet: A Comprehensive
Resource Guide. Saskatchewan, Canada: Case Nutrition Consulting,
2006.
9. Laiho K, Hoppu U, Ouwehand AC, et al. Probiotics:
On-going research on atopic individuals. Br J Nutr. 2002;88(Suppl
1):519-527.
10. Melina V, Aronson D, Stepaniak J. Food Allergy
Survival Guide: Surviving and Thriving With Food Allergies and
Sensitivities. Summertown, Tenn.: Healthy Living Publications,
2004.
Examination
1. Which of the following is a concern with inappropriate wound
healing due to malnutrition?
a. low tensile strength of the scar
b. increased risk of infection
c. risk of cancer at the wound site
d. a and b
2. Which of the following is found in high concentration
at the wound site and is crucial in all stages of wound healing?
a. vitamin A
b. zinc
c. biotin
d. manganese
3. What is a major role of vitamin C in the
skin?
a. moisture retention
b. reduced incidence of acne
c. improved tanning
d. collagen production
4. What is a major source of damage caused by
ultraviolet (UV) exposure?
a. free radicals
b. dehydration
c. accumulation of copper
d. inadequate iron
5. Which of the following is the best defense
against skin damage due to UV exposure?
a. zinc
b. calcium
c. probiotics
d. antioxidants
6. Which nutrient is the most important in reducing
fluid loss of skin tissue?
a. vitamin D
b. essential fatty acids
c. iron
d. phosphorus
7. Which of the following are symptoms of polycystic
ovary syndrome (PCOS)?
a. insulin resistance
b. elevated androgens
c. irregular menstrual cycles
d. all of the above
8. Which condition may benefit from probiotic
use?
a. atopic dermatitis
b. PCOS
c. skin melanoma
d. psoriasis
9. Which condition may benefit from omega-3
fatty acids?
a. psoriasis
b. atopic dermatitis
c. skin aging
d. all of the above
10. Which of the following conditions may benefit
from a gluten-free diet?
a. dermatitis herpetiformis
b. aging skin
c. acanthosis nigricans
d. atopic dermatitis
