Results of a  study carried out by the Helmholtz Centre for Environmental Research and the Martin Luther University in Halle-Wittenberg in Germany indicate a link between high vitamin D levels in expectant mothers and increased infant allergy risks. These results were published in the February issue of the medical journal Allergy.

The conclusion drawn from the study states that pregnant women should avoid taking vitamin D supplements because this appears to raise the risk of children developing a food allergy after birth until their 2nd birthday.

A total of  622 mothers and their 629 children were included in the long-term study “Lifestyle and environmental factors and their impact on the newborn allergy risk” says  Dr. Irina Lehmann who headed the study.

Vitamin D is one of those nutrients that always had a good reputation for supplementation. Many mothers are found to be vitamin D deficient when they enter pregnancy and it is becoming increasingly popular for pregnant mothers to be told to take a vitamin D supplement. However, recent scientific investigations are increasingly questioning the positive aspect of the  vitamin D supplementation. At the end of the 1990’s, for the first time people’s attention was drawn to a link between high vitamin D levels and the development of allergies.

This study aimed to find out if  there is a correlation between the concentration of vitamin D in the blood of expectant mothers and in cord blood of the babies as well as the association between vitamin D levels during pregnancy and at birth, the immune status and the incidence of allergic diseases of the children later in life.

Vitamin D in Pregnancy. A good source is the sunshine.In short… They found that yes, the baby’s vitamin D levels are similar to the mothers at birth, and that babies with excess levels of vitamin D have fewer regulatory T-cells which stop the immune system from overreacting to allergens. Fewer regulatory T cells  results in a higher chance of developing one or more allergies.

The final recommendation of the study was a little puzzling to me. This recommendation is to avoid vitamin D supplementation in pregnancy. I fore-see a future where this is translated as “vitamin D is dangerous to take in pregnancy” as has happened with vitamin A ( a whole ‘nother kettle of fish and a topic for some other time). The  major problem I see with this blanket recommendation is that it seems to ignore the fact that vitamin D deficiency is more common than an excess of vitamin D and the problems with this are just as troubling. In pregnancy, vitamin D helps to develop baby’s bones. A vitamin D deficiency can affect the amount of calcium the baby has in their bones and in severe deficiency this can cause a bone deformity called rickets. Since the baby is getting it’s vitamin D from mum, mum has in increased need for it for her own bone health and a mother deficient in vitamin D is more likely to suffer post natal depression.

I do agree that routine vitamin D supplementation should be avoided during pregnancy. Routine vitamin D supplementation should be avoided for ALL people. Vitamin D is a fat soluble vitamin so your body doesn’t just pee it out like some others. It’s stored in fat cells and it’s hard to get rid of it if you go overboard. We’ve known for a long time that it’s toxic in high doses.

It’s a simple enough procedure to test a mother’s vitamin D status and make recommendations according to her results. For many women, diet and lifestyle modifications alone can boost her vitamin D to optimal levels. For others, this might not be enough and a vitamin D supplement might be necessary. A simple blood test will tell what’s required for each individual.

So how do you ensure you have enough vitamin D without getting too much?

1. Get some sunshine 

It depends on where you live as to how much sunlight you need each day to keep your vitamin D levels up. Your body will never make too much from sunlight alone.

It’s obviously important to get enough sunlight to produce vitamin D without increasing your risk of skin cancer. In summer, many fair skinned people make enough vitamin D from having their hands, arms and face (or equivalent area of skin) in the sun for a few minutes each day during normal day to day outdoor activities. This is without the slip, slop, slap. Sunscreen, hats and layers of clothing will reduce your body’s ability to make vitamin D, so you need to make sure that you get some direct sunshine to your skin without sunscreen and protective clothing. You should choose your timing sensibly. Don’t go get your vitamin D fix at the beach in the middle of summer at midday for example.

In most of Australia, in winter, you will need two to three hours of sunlight each week. In Summer, 5-15 mins a day should do it.

People with darker skin need more sunlight and those with very black skin may need three to six times as much sunlight as fair skinned people.

2. From your diet

While there is vitamin D in some foods, there is not enough to give you what you need, you still need sunlight. Vitamin D is present in a small number of foods, for the average person food will  supply about 10% of the amount they need. You can up that to around 90% if you try hard enough with your diet. Vitamin D is present in oily fish such as mackerel, tuna, salmon and sardines. Other great sources are eggs, shitaake mushrooms, button and field mushrooms the mushrooms make vitamin D2 which is a little harder for your body to use than the animal sourced vitamin D3, but they are still helpful).

3. If you do need to take a supplement, choose carefully

Have your levels rechecked after a maximum of 3 months of supplementation to see if it’s still required.

Vitamin D supplements come in two forms:

  1. Ergocalciferol (vitamin D2) a synthetic version made by irradiating fungus and plant matter—this would be the form of vitamin D suitable for a vegan lifestyle. This is not as well absorbed or utilised by your body as vitamin D3. This is the most common type available. Always check the label to see what type you are buying.
  2. Cholecalciferol (vitamin D3) the same type of D vitamin created in your body when you expose your skin to sunlight. This is  87 percent more potent in raising and maintaining vitamin D concentrations and produces 2- to 3-fold greater storage of vitamin D than does D2. It is only produced by vertebrate animals and is not available in plant based supplements.



The study cited in this post:

The press release that alerted me to this study: