Tuesday, October 30, 2012

How Much Vitamin D is Safe?

By Dr. Iva Lloyd, ND

There has been a lot in the media over the last couple of years encouraging people to take high doses of vitamin D. The potential benefits of supplementation include:
  • fewer falls and fractures
  • increased bone density
  • prevention of influenza virus
  • prevention or reduction in asthma attacks
  • increased insulin sensitivity
  • decreased blood pressure
  • and the prevention of some cancers and autoimmune disease
Not that long ago the recommended dosage for vitamin D supplementation was 400 iu / day.  Currently it is not unusual for individuals to be dosing at 10 to 20 times that amount. Lately it has been questioned whether or not the benefits of vitamin supplementation are still achieved at high dosages. The concerns include:

  • Serum 25 hydroxyvitamin D (the standard blood test for vitamin D status) may not be a reliable indicator as it's half-life is 3 weeks. Also, 25 hydroxyvitamin D is only one of more than 50 vitamin D metabolites in blood and it is questionable as to the validity of using it as the primary indicator.
  • The safety and efficacy of vitamin D supplementation cannot be inferred from data regarding the safety and efficacy of sunlight exposure. Many of the promoted benefits of vitamin D supplementation are actually from studies looking at sunlight exposure itself.
  • Vitamin D is a fat-soluble nutrient and hence it can accumulate within the body and cause other concerns. For more information: http://www.ndhealthfacts.org/wiki/Vitamin_D
  • Most of the studies on vitamin D supplementation are less than 20 weeks long hence the long-term safety of dosages greater than 2,000 IU/day is questionable.
  • Vitamin D levels decline in response to inflammation. Therefore low levels of vitamin D may be more indicative of inflammation level versus vitamin D status.
  • There are some studies that indicate that vitamin D supplementation may exacerbate atherosclerosis.
  • Studies suggest that moderate dosages of vitamin D may be protective against cancer; whereas high doses were not and may actually increase the risk.
  • Bone density measurements were better with low-to-moderate dosages of vitamin D.
There are some conditions, such as celiac disease, Crohn's, multiple sclerosis and some cancers where dosing high with vitamin D may be advantageous.  The new research indicates that 800 to 1200 IUs / day is generally effective for most people. Ideally, the best way to ensure adequate vitamin D status is to enjoy 5-15 minutes of sunlight exposure 2 to 3 times a week between 10 a.m. and 3 p.m.

If you have any questions about the optimal amount of vitamin D supplementation for yourself, talk to your naturopathic doctor.

Reference:
Gaby, Alan 2011 Controveries in Nutrition. Presented at the Ontario Association of Naturopathic Doctors annual Conference.

Wednesday, October 24, 2012

Iron-Rich Foods at 6 months?...New guidelines miss the point

A recent update to Health Canada's Infant Feeding Guidelines has sent ripples of interest through parenting communities.  The guidelines, intended to inform health care professionals on appropriate first foods to recommend to parents, reinforced the 2004-05 guideline message that iron-rich foods are important to include as some of babies first foods.  The guideline provided for the first time examples of such foods, including beef, poultry, fish, eggs and soy.

Iron is an important mineral we require throughout our lives.  It helps build blood, transport oxygen, provides energy, helps build hormones and protects the immune system. 

Why all the fuss?  Well, to begin with, most parents are familiar with giving infants "iron-fortified" cereals, and not as familiar with pureed steak and mashed fish.  If we look at traditional diets from around the world we see that most cultures introduce iron-rich foods well before starchy foods like grains and legumes.  Nature does a great job of providing us with balanced foods.  In our boxed and packaged world we seem to think adding iron to carbs is just as effective as eating foods naturally high in iron.  This is not the case.  Eating whole foods, grown in and on a healthy land, is the most effective way to achieve a truly balanced diet.

What people are missing:

So, yes, consuming foods high in iron will be the most effective way of increasing iron stores in the body.  But why are our kids low in iron in the first place?  One little line ignored for the most part in the Health Canada Infant-Feeding Guideline gives us the answer: "Most healthy term infants are born with sufficient iron stores to meet their iron needs until they are about six months".  What happens at 6 months?  Two things actually change at this point: infant requirements for iron almost double, and breast milk continues to decline in iron content.  The iron status in breast milk cannot be altered by maternal iron supplementation after birth.  So in healthy children where does the extra iron for baby come from?  Here's the "Ah Ha moment" most people seem to be missing.  At 6 months of age infants begin aggressively drawing on their own iron body reserves, reserves that are the result of 9 months in mom.  When mom's iron stores are low prior to pregnancy and/or iron intake during pregnancy is low, baby is born with reduced iron stores and will certainly need to be supplemented earlier on with iron-rich foods.Children who are born to mothers with appropriate (not just low-normal) iron stores are perfectly set up for at least 12 months of healthy iron status after birth.

No surprise, the real solution to iron-deficiency in infants is proper pre-natal and peri-natal support.  Health promotion over disease management.

Iron status is only one of the variables Naturopathic Doctors evaluate in pregnancy planning visits.  If you are currently pregnant or planning on getting pregnant, come in soon and speak to one of our NDs.