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Green Living – Improving Air Quality with Common Houseplants

Houseplants for Cleaner Air
Gerbera Daisy – Gerbera jamesonii

Living indoor plants add a natural beauty to our homes and workplaces and offer a welcome glimpse of green in the depths of a Canadian winter, but did you know they can also purify the air we breathe and contribute to a healthy home and office?

NASA’s Plant Program

In the late 1980s NASA researchers began looking at houseplants as a potential means of cleansing the atmosphere in future space stations.They discovered that many common houseplants help diminish indoor air pollution by removing harmful gases from the air, through the simple processes of photosynthesis.Other pollutants are absorbed by the plants and rendered harmless in the soil.

Plants are known to absorb carbon dioxide and release oxygen but the NASA researchers found that many houseplants are also able to absorb benzene, formaldehyde and tricholoroethylene.

Indoor Air Pollutants and Sick Building Syndrome

These three chemicals (benzene, formaldehyde and trichloroethylene) are among the most common airborne pollutants in new homes and offices.Newer buildings are constructed largely with synthetic materials containing these and other harmful materials which are known to “off-gas” pollutants into the indoor air.This “off-gassing” combined with heavily insulated buildings and reduced fresh air exchange resulted in an increased incidence of “sick building syndrome” (SBS), a medical syndrome associated with indoor air pollution and diminished air circulation.

Symptoms of SBS range from specific symptoms such as itchy eyes, skin rashes, and nasal allergy symptoms, to more vague symptoms such as fatigue, aches and pains, and sensitivity to odours.See Table 1 for symptoms associated with the different indoor air pollutants.

Table 1: Indoor Air Pollutants – Sources and Symptoms of Exposure

Air Pollutant

Source

Symptoms

Formaldehyde

Insulation
Particle boardPressed wood products (MDF – medium density fiberboard)
Consumer paper products
Carpet backing
Floor coverings
Water repellants
Fire retardants
Permanent-pressed clothes
Natural gas
Kerosene
Cigarette smoke

Eye irritation
Nose irritation
Throat irritation
Contact dermatitis (skin rashes)
Headaches
Asthma
Potential human carcinogen

Benzene

Inks
Oils
Paints
Plastics
Rubber
Detergents
Dyes

Skin irritation
Eye irritation
Dizziness
Weakness
Headache
Nausea
Blurred vision
Drowsiness
Potential human carcinogen

Trichloroethylene

Dry cleaning
Inks
Paints
Varnishes
Lacquers
Adhesives


Liver carcinogen

Shade Loving Plants – The Best Air Purifiers

Bamboo palm
Bamboo Palm – Chamaedorea sefritzii

The plants NASA determined to be most effective in purifying indoor air are plants that evolved in tropical or sub-tropical forests, where they received light filtered through the branches of taller trees.

Because of the low-light conditions in their natural environment these plants became very efficient photosynthesizers.They are able to absorb and neutralize gases in the air easily with only indirect sunlight.This feature also makes them excellent indoor plants because they don’t require direct sunlight to thrive and grow.

Allowing air to contact the soil increases the amount of air pollution that will be processed by the houseplants.Micro-organisms in the soil use trace amounts of airborne chemicals as a food source.Their effectiveness is increased if lower leaves that cover the soil surface are removed, allowing more air to contact the soil surface.

Choosing an Indoor Houseplant

Sansevieria trifasciata
Snake Plant or “Mother-in-law’s tongue”

The NASA studies recommend that you use 1 good-sized houseplant in a 6 to 8-inch diameter container for each 100 square feet of indoor space.A more heavily polluted environment would require a greater number of plants.And the better they grow, the better job they will do purifying the air for you!

The plants found to be most effective at cleansing indoor air pollution by NASA scientists are:

  • Hedera helix – English ivy
  • Chlorophytum comosum – Spider plant
  • Epipiremnum aureum – Golden pothos
  • Spathiphyllum ‘Mauna Loa – Peace lily
  • Aglaonema modestum – Chinese evergreen
  • Chamaedorea sefritzii – Bamboo or reed palm
  • Sansevieria trifasciata – Snake plant or Mother-in-law’s tongue
  • Philodendron scandens ‘oxycardium’ – Heartleaf philodendron
  • Philodendron selloum – Selloum philodendron
  • Philodendron domesticum – Elephant ear philodendron
  • Dracaena marginata – Red-edged dracaena
  • Dracaena fragrans ‘Massangeana’ – Cornstalk dracaena or Mass cane
  • Dracaena deremensis ‘Janet Craig’ – Janet Craig dracaena
  • Dracaena deremensis ‘Warneckii’ – Warneck dracaena
  • Ficus benjamina – Weeping fig or Ficus
  • Gerbera jamesonii – Gerbera daisy
  • Chrysanthemum morifolium – Pot chrysanthemum

Resources:

Information taken from the NASA report Interior Landscape Plants for Indoor Air Pollution Abatement, September 1989.Dr. B.C. Wolverton, Anne Johnson, and Keith Bounds, National Aeronautics and Space Administration, John C. Stennis Space Center, Science and Technology Laboratory, Stennis Space Center,MS 39529-6000.

Living indoor plants add a natural beauty to our homes and workplaces and offer a welcome glimpse of green in the depths of a Canadian winter, but did you know they can also purify the air we breathe and contribute to a healthy home and office?

NASA’s Plant Program

In the late 1980s NASA researchers began looking at houseplants as a potential means of cleansing the atmosphere in future space stations.  They discovered that many common houseplants help diminish indoor air pollution by removing harmful gases from the air, through the simple processes of photosynthesis.  Other pollutants are absorbed by the plants and rendered harmless in the soil.

Plants are known to absorb carbon dioxide and release oxygen but the NASA researchers found that many houseplants are also able to absorb benzene, formaldehyde and tricholoroethylene.

Indoor Air Pollutants and Sick Building Syndrome

These three chemicals (benzene, formaldehyde and trichloroethylene) are among the most common airborne pollutants in new homes and offices.  Newer buildings are constructed largely with synthetic materials containing these and other harmful materials which are known to “off-gas” pollutants into the indoor air.  This “off-gassing” combined with heavily insulated buildings and reduced fresh air exchange resulted in an increased incidence of “sick building syndrome” (SBS), a medical syndrome associated with indoor air pollution and diminished air circulation.

Symptoms of SBS range from specific symptoms such as itchy eyes, skin rashes, and nasal allergy symptoms, to more vague symptoms such as fatigue, aches and pains, and sensitivity to odours.  See Chart 1 for symptoms associated with the different indoor air pollutants.

Chart 1: Indoor Air Pollutants – Sources and Symptoms of Exposure

If you live or work in an older building sick-building syndrome is not likely to affect you.  But if you live in a newer, energy-efficient home or work in a building with poor air circulation, the use of houseplants may help to alleviate some of the air quality issues in your indoor environment.

Shade Loving Plants – The Best Air Purifiers

The plants NASA determined to be most effective in purifying indoor air are plants that evolved in tropical or sub-tropical forests, where they received light filtered through the branches of taller trees.

Because of the low-light conditions in their natural environment these plants became very efficient photosynthesizers.  They are able to absorb and neutralize gases in the air easily with only indirect sunlight.  This feature also makes them excellent indoor plants because they don’t require direct sunlight to thrive and grow.

Allowing air to contact the soil increases the amount of air pollution that will be processed by the houseplants.  Micro-organisms in the soil use trace amounts of airborne chemicals as a food source.  Their effectiveness is increased if lower leaves that cover the soil surface are removed, allowing more air to contact the soil surface.

Choosing an Indoor Houseplant

The NASA studies recommend that you use 1 good-sized houseplant in a 6 to 8-inch diameter container for each 100 square feet of indoor space.  A more heavily polluted environment would require a greater number of plants.  And the better they grow, the better job they will do purifying the air for you!

The plants found to be most effective at cleansing indoor air pollution by NASA scientists are:

  • Hedera helix – English ivy
  • Chlorophytum comosum – Spider plant
  • Epipiremnum aureum – Golden pothos
  • Spathiphyllum ‘Mauna Loa – Peace lily
  • Aglaonema modestum – Chinese evergreen
  • Chamaedorea sefritzii – Bamboo or reed palm
  • Sansevieria trifasciata – Snake plant or Mother-in-law’s tongue
  • Philodendron scandens ‘oxycardium’ – Heartleaf philodendron
  • Philodendron selloum – Selloum philodendron
  • Philodendron domesticum – Elephant ear philodendron
  • Dracaena marginata – Red-edged dracaena
  • Dracaena fragrans ‘Massangeana’ – Cornstalk dracaena or Mass cane
  • Dracaena deremensis ‘Janet Craig’ – Janet Craig dracaena
  • Dracaena deremensis ‘Warneckii’ – Warneck dracaena
  • Ficus benjamina – Weeping fig or Ficus
  • Gerbera jamesonii – Gerbera daisy
  • Chrysanthemum morifolium –  Pot chyrsanthemum

 

Resources:

Information taken from the NASA report Interior Landscape Plants for Indoor Air Pollution Abatement, September 1989.  Dr. B.C. Wolverton, Anne Johnson, and Keith Bounds, National Aeronautics and Space Administration, John C. Stennis Space Center, Science and Technology Laboratory, Stennis Space Center,  MS 39529-6000.

Epsom Salts – Baths and Beyond

 

Epsom salt bath

There is nothing better in winter than a nice hot bath.  And a bath that was prescribed by your Naturopathic Doctor is even better.  Just tell your partner, roommate or kids that you *need* to spend 20 minutes enjoying a quiet soothing bath – your doctor told you to do it.

Why take an Epsom Salts bath?

An Epsom salts bath releases toxins and metabolic waste by enhancing perspiration.  Epsom salts also contain magnesium sulfate, which when absorbed by the body promotes muscle relaxation and relieves stiff, aching and cramped muscles.

Epsom salt baths can also be used to treat specific conditions.  Dry skin can benefit from Epsom salt baths as can genital herpes outbreaks.

The Epsom Salts bath

Step 1: Add two cups (approximately 600g) of Epsom salts to a hot bath (38 to 44 degrees Celsius or 100.4F to 111.2F).  Soak in the hot bath for 15 to 20 minutes.

Step 2: While in the bath wrap a cool wet towel around your neck (a hand towel dipped in cold water works well) and drink cool filtered water to replace fluids that are lost.

Step 3: When finished the bath, cool your body down with a cool shower or a cool sponge bath – starting from the feet and moving upwards.

Step 4: Rest for 15 to 30 minutes after the bath for maximal relaxation and therapeutic impact.

Additional notes:

  • Do not use soaps while in the Epsom salt bath.
  • Taking an Epsom salt bath after a massage can enhance and lengthen the effect of a massage.
  • Take an Epsom salt bath two to three times per week for best results.

Other Uses for Epsom Salts

Epsom salts can be used to treat acne and skin blemishes.   Mix 1 tablespoon of Epsom salts in ½ cup of warm water.  Wash face with the mixture twice daily.  Use just once daily if you have very sensitive or dry skin.  Discontinue use if skin irritation occurs.  You could also use a poultice and apply just to blemishes (see below for instructions on how to make a poultice).

A Epsom salts poultice can also be used to draw out boils, carbuncles or abscesses.  The salts are a natural antiseptic and antimicrobial and help to absorb the moisture from the area, drying out the boil.  Use a poultice and apply to the affected area for 5 to 10 minutes then rinse with cool water.

HOW TO MAKE AN EPSOM SALTS POULTICE

Place 1 to 2 tablespoons of Epsom salts in a glass bowl

Add just enough warm water to make a thick paste

Apply to blemishes, boils, carbuncles, abscesses or herpes outbreaks once to twice daily

Leave on skin for 5 to 10 minutes then rinse off with cool water

Caution!

Epsom salt baths are relaxing to your body and mind but are stimulating to your circulatory system.  It is not recommended for people with high blood pressure or severe varicose veins to use Epsom salt baths.

Disclaimer

The advice provided in this article is for informational purposes only.  It is meant to augment and not replace consultation with a licensed health care provider.  Consultation with a Naturopathic Doctor or other primary care provider is recommended for anyone suffering from a health problem.

References

Boyle, Wade and Saine, Andre.  Lectures in Naturopathic Hydrotherapy.  1988.

Rosemary Waring Absorption of magnesium sulphate through the skin (republished by the Epsom Salt Council), 2004

10 Things You Need to Know About Vitamin D

The importance of Vitamin D to health can not be underestimated.  It is the only vitamin that our body makes from exposure to sunlight.  Learn 10 important things about the “sunshine vitamin” and discover the impact Vitamin D can have on your health.

1. Vitamin D is made from sunlight

Vitamin D SunriseVitamin D is often referred to as the “sunshine vitamin” because our skin produces vitamin D from the sun’s ultraviolet light (UVB).  Our skin can make enough vitamin D in 30 minutes with just our face, hands and feet exposed.  Full body exposure for 15 minutes can produce between 10 000 – 20 000IU (international units) of vitamin D3.  However, many factors influence our body’s ability to produce vitamin D: complexion, use of sunscreen, cloud cover, smog, time of day, latitude and season.

Individuals with darker complexions make less vitamin D than fair-skinned people.  Studies estimate that half of all women of African descent living in northern latitudes are vitamin D deficient.

Sunscreen use is important for the prevention of skin cancer but it has the unfortunate effect of blocking vitamin D production by blocking UVB rays from reaching our skin.

Cloud cover can reduce UVB energy by 50%, shade reduces it by 60%.  UVB rays do not penetrate glass, so exposure to sunshine indoors does not promote vitamin D production.

2. Vitamin D deficiency is a major concern during Canadian autumns and winters

Latitude has a lot to do with vitamin D status.  Due to our northern latitude the majority of Canadians have insufficient vitamin D levels during the fall and winter months.  One study demonstrated that in Canada from November through February UVB rays aren’t strong enough for our bodies to produce enough vitamin D.

Vitamin D stores in our bodies are quickly depleted during the early autumn months leading to insufficient levels during the late autumn and winter.  Vitamin D is stored in the blood for a few weeks and in fat tissue for a few months.

The average vitamin D level in late winter for American and Canadians is approximately 15-18ng/ml – levels below 20ng/ml are considered seriously deficient.

3. Vitamin D can help prevent Influenza and the Common Cold

Pediatric Naturopathic MedicineEach year more studies are showing a relationship between low vitamin D levels and incidence of colds, influenza and other respiratory tract infections.

People with higher vitamin D levels experience fewer respiratory illnesses and when they do get sick the illness is milder and shorter.  The Public Health Agency of Canada is currently investigating the role of vitamin D in the protection against season influenza and the H1N1 (swine flu) strain.

Vitamin D levels in your blood are at their lowest point during flu season.  Your body uses vitamin D to make antimicrobial peptides – the body’s natural antibiotics.  When vitamin D is deficient you make fewer peptides and are more vulnerable to illness.

Infants and children are a population where respiratory tract infections can have serious health implications.  Infants and children with lower levels of vitamin D are more susceptible to viral infections.

Vitamin D supplementation may be used to prevent or treat influenza.  To treat influenza larger doses of vitamin D3 may be needed.  It is best to consult with a Naturopathic Doctor if you are considering taking high doses of vitamin D as it can be toxic in high doses.

4. Vitamin D may prevent Cancer

You might not know it, but the connection between vitamin D status and cancer is well established in the scientific community.  Adequate levels of vitamin D have been shown to decrease the risk of developing over 16 different types of cancer including breast, ovarian, prostate, pancreatic, colon, non-Hodgkins lymphoma and lung cancer. It is also an important part of integrative cancer treatment protocols.

A study by Dr. W. Grant, vitamin D expert, found that about 30 percent of all cancer deaths (2 million worldwide) could be prevented each year with higher levels of vitamin D.

Vitamin D can protect against cancer in several ways, including:

  • Increased self-destruction (apoptosis) of mutated cells
  • Reduced spread (metastasis) and reproduction (proliferation) of cancer cells
  • Increased differentiation of cells (cancer cells often lack differentiation)
  • Reduced growth of new blood vessels from pre-existing ones, which is a step in the transition of dormant tumors turning cancerous

Other studies have estimated that you can decrease your risk of developing cancer by more than half by optimizing vitamin D levels.

5. Vitamin D is essential for bone health

Vitamin D is necessary for healthy bonesVitamin D deficiency results in childhood rickets and in osteomalacia (under-mineralized bone) in adults.  Without sufficient vitamin D bones become thin, brittle or misshapen.

Osteoporosis is a very common disease in North America.  It is characterized by fragile bones that significantly increase the risk of fracture.  Long term vitamin D insufficiency is associated with the development of osteoporosis.  Supplementing calcium and vitamin D can help protect adults from developing osteoporosis.  Vitamin D is necessary to allow the body to absorb calcium, either from dietary or supplemental sources.  Vitamin D also lowers the risk of fractures in people with osteoporosis.

6. Vitamin D can decrease the risk of Auto-Immune diseases

Vitamin D is one hard working vitamin!  Not only can it decrease the risk of cancer, common cold, influenza and osteoporosis, but it can also decrease the risk of developing several auto-immune diseases.  Conditions such as autism, type I diabetes mellitus, schizophrenia and rheumatoid arthritis all have been correlated with low levels of vitamin D.

One auto-immune condition has been studied extensively with relation to vitamin D status.  Multiple sclerosis (MS) is a chronic auto-immune disease that occurs almost exclusively in extreme latitudes and rarely near the equator.  In MS the immune system attacks the body’s own cells as “foreign”, causes vision changes and muscle weakness.  Adequate vitamin D levels may decrease the incidence of MS.  It is also an important integrative treatment for people with MS.

7. Vitamin D is essential for children and breastfed infants

Levels of vitamin D in breast milk have been found to be lower than needed for proper growth and development in infants (breast milk contains about 25IU/litre).  Because of this finding breastfed infants are recommended to be supplemented with 400IU of vitamin D daily (formula is also supplemented with vitamin D).  Supplementing at this young age could have life-long benefits.

Older children and adolescents also benefit from vitamin D supplements.  The American Academy of Pediatrics suggests supplementing all children to ensure adequate vitamin D levels.

8. Vitamin D can help prevent Type I and Type II Diabetes

More obese adults are deficient in vitamin D than same-age adults with normal weights.   A large percentage of adults with type II diabetes are also obese.  60% of people with type II diabetes have inadequate levels of vitamin D in their blood.  If you are obese, supplementing with vitamin D may help decrease your risk of developing type II diabetes.  If you already have type II diabetes supplementing with vitamin D can help improve insulin sensitivity.

Scientific studies have also established a link between type I diabetes and vitamin D levels.  Deficient levels of vitamin D are frequently found in patients diagnosed with type I diabetes and some research supports supplementation of vitamin D to decrease the risk of type I diabetes.  Children supplemented with vitamin D were also found to be less likely to develop type I diabetes.

9. Vitamin D levels can be tested – and should be!

The only way to determine the correct dose of vitamin D for you to take is to get your blood levels tested.  There are currently 2 different vitamin D tests available.  The best one is 25-hydroxyvitamin D.  This is a better marker of overall vitamin D status than 1,25-hydroxyvitamin D.

Vitamin D levels should be tested for three reasons.

  1. Vitamin D requirements are different for everyone. Depending on your age, colour of your skin, weight, and latitude of the town you live in, you could need anywhere from 400IU to over 10 000IU per day!
  2. Vitamin D can be toxic in excessive doses. Vitamin D accumulates in fat tissues where it is stored for a few months.  Vitamin D overdose causes hypercalcemia (too much calcium in the blood), dehydration and tissue calcification.  Blood tests showing levels of greater than 200nmol/L of vitamin D are toxic.  It is very difficult to reach this level through sunlight exposure or nutritional sources of vitamin D.  Toxicity has been seen with long term supplementation of excessive levels of vitamin D.  Having your blood levels tested will ensure you are not taking excessive dosages of vitamin D.
  3. Vitamin D insufficiency is often asymptomatic. It is possible to have low levels of vitamin D in your body and not be aware of it.  The only way to know you have optimal levels of vitamin D is to test for it.

Vitamin D Levels (25-hydroxyvitamin D)

Deficient Insufficient Optimal Cancer therapy Excess
<25ng/ml <35ng/ml 50-65ng/ml 65-90ng/ml >100ng/ml
<20nmol/L <40-80nmol/L 80-120nmol/L 120-160nmol/L >200nmol/L

10. Not all Vitamin D supplements are created equal

gel cap skyThere are two types of vitamin D available; Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol).  Only Vitamin D3 should be used for supplementation.  Vitamin D2 is a synthetic form of Vitamin D and does not impact vitamin D stores in our bodies in the way Vitamin D3 does.  Vitamin D3 is the natural form, the same form our bodies create from sun exposure.

Vitamin D3 is better absorbed in a liquid form.  Several companies make liquid Vitamin D3.

Food sources of Vitamin D3 (fortified milk, fish, cod liver oil, egg yolk, mushrooms) are often insufficient to maintain optimal levels of Vitamin D3.  Especially during the winter months in Canada, supplementation is necessary.

As of 2012, the conventional RDAs (recommended daily allowances) in Canada are only:

  • 400 IU for infants and children
  • 600 IU for adolescents and adults aged 9-70
  • 800 IU for adults over 70
  • 600 IU for pregnant and breastfeeding women

These levels are completely inadequate for maintaining optimal health, especially in the autumn and winter months in Canada.  The only way to determine an adequate (and safe) dosage of Vitamin D is with a blood test.  However, general guidelines from the scientific literature suggest a dosage of:

Vitamin D3 Dosage Guidelines

35IUs of Vitamin D3 per pound of body weight

For a child weighing 40 pounds, a dosage of approximately 1400 IU would be reasonable and for a 160 pound adult the dose would be approximately 5600 IU’s.  This dosage is for a fair skinned healthy young adult.  It is a guideline only and does not suggest that all adults and children should be taking these doses.

Conclusion

Achieving adequate levels of vitamin D is important!  Reduce your risk of cancer, influenza, respiratory tract infections, diabetes, auto-immune diseases and improve your bone health and overall health with just one vitamin supplement daily.

Photo courtesy of Jamie Amodeo. www.flickr.com/jamieamodeo

Photo Credit: ellesmere FNC via Compfight cc

Resources:

Aloia JF, Ni-Ng M.  Re: epidemic influenza and vitamin D.  Epidemiol Infect.  2007 Oct;135(7):1095-6; author reply 1097-8.

Aloia JF, Patel M, Dimaano R, Li-Ng M, et al.  Vitamin D intake to attain a desired serum 25-hydroxyvitamin D concentration.  Am J Clin Nutr.  2008 Jun;87(6): 1952-8.

Autier P, Gandini S.  Vitamin D Supplementation and Total Mortality: A Meta-analysis of Randomized Controlled Trials.  Arch Intern Med.  2007 Sep 10;167(16):1730-7.

Cannell JJ, Vieth R, Umhau JC, et al.  Epidemic influenza and vitamin D.  Epidemiol Infect.  2006 Dec;134(6):1129-40.

Cannell JJ, Zasloff M, Garland CF, Scragg R, Giovannucci E.  On the epidemiology of influenza.  Virol J.  2008 Feb 25;5:29.

Ginde AA, et al.  Association between serum 25-hydroxyvitamin D level and upper respiratory tract infection in the Third National Health and Nutrition Examination Survey.  Arch Intern Med.  2009 Feb 23;169(4):384-90.

Grant WB. An estimate of premature cancer mortality in the United States due to inadequate doses of solar ultraviolet-B radiation, Cancer, 2002b;94:1867-75

Grant WB.  Geographic variation of prostate cancer mortality rates in the USA; implications for prostate cancer risk related to vitamin D; Int. J. Cancer, 2004 Sep 1;111(3):470-1

Grant WB. Lower vitamin-D production from solar ultraviolet-B irradiance may explain some differences in cancer survival rates.  J Natl Med Assoc.  2006 Mar;98(3):357-64.

Gordon CM, Feldman HA, Sinclair L, et al.  Prevalence of Vitamin D Deficiency Among Healthy Infants and Toddlers.  Arch Pediatr Adolesc Med.  2008;162[6]:505-512.

Health Canada, Vitamin D and Calcium: Updated Dietary Reference Intakes: http://www.hc-sc.gc.ca/fn-an/nutrition/vitamin/vita-d-eng.php

Holick MF.  Calcium and Vitamin D.  Diagnostics and Therapeutics.  Clin Lab Med.  2000 Sep;20(3):569-90

Holick MF. High prevalence of vitamin D inadequacy and implications for health. Mayo Clin Proc. 2006

Mar;81(3):353-73

Hypponen E, Laara E, Reunana A, Jarvelin MR, Virtanen SM.  Intake of vitamin D and risk of type 1 diabetes: a birth-cohort study.  Lancet.  2001;358:1500-3.

Ingraham BA, Bragdon B, Nohe A.  Molecular basis of the potential of vitamin D to prevent cancer.  Curr Med Res Opin.  2008;24:139-49.

Laaksi I, et al.  An association of serum vitamin D concentrations <40nmol/L with acute respiratory tract infection in young Finnish men.  Am J Clin. Nutr.  2007 Sep;86(3):714-7.

Mayo Clinic Information Sheets: www.mayoclinic.com/health/vitamin-d/NS_patient-vitamind”>vitaminD

Dr. Mercola website: http://articles.mercola.com/sites/articles/archive/2004/03/31/cancer-sunlight.aspx

Merlino LA, Curtis J, Mikuls TR, et al.  Vitamin D intake is inversely associated with rheumatoid arthritis: results from the Iowa Women’s Health Study.  Arthritis Rheum.  2004;50:72-7.

Munger KL, Levin Ll, Hollis BW, Howard NS, Ascherio A.  Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis.  JAMA.  2006 Dec 20;296(23):2832-8.

Robsahm TE, Tretli S, Dahlback A, Moan J.  Vitamin D(3) from sunlight may improve the prognosis of breast-, colon- and prostate cancer (Norway).  Cancer Causes Control.  2004;15:149-58.

Wagner CL, Greer FR: American Academy of Pediatrics Section on Breastfeeding: American Academy of Pediatrics Committee on Nutrition.  Prevention of rickets and vitamin D deficiency in infants, children, and adolescents.  Pediatrics 2008;122:1142-52.

Webb AR, Kline L, Holick MF.  Influence of season and latitude on the cutaneous synthesis of vitamin D3: exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin.  J Clin Endocrinol Metabl.  1988;67:373-8.

Zella JB, DeLuca HF.  Vitamin D and autoimmune diabetes.  J Cell Biochem.  2003;88:216-22