Category Archives: Nutrition

Vitamin D (Part 2): Where do we get it?

Okay, now for a bit more detail about Vitamin D. In this post we’ll look at where it comes from, and how we get it to where it’s needed in the body.

1) Vitamin D metabolism

There are actually two forms of vitamin D: vitamin D2, which is synthesized by plants,  and vitamin D3 (cholecalciferol), which is synthesized by mammals, including us. This review will focus on D3, since that’s the most important form for humans.

There are two ways that humans get their daily vitamin D: sunshine (the most effective way) and diet.

Not exactly true...

First let’s clear up a common vitamin D misconception. We do not get vitamin D directly from the sun–that is, there are no tiny “Ds” raining down on us while we sunbathe by the pool. Rather, sunlight acts on a cholesterol-based vitamin D precursor our bodies make and converts that to previtamin D  in the skin. Previtamin D is then converted to vitamin D3 by the heat of the skin.

That’s just the beginning…

Once it leaves the skin, vitamin D3 jumps on board a specialized protein that transports it to the liver, where it’s converted to 25-hydroxyvitamin D (25-OH-D). From there 25-OH-D surfs to the kidneys on another specialized protein where, through the mysteries of biochemistry, it transforms itself into 1,25-dihydroxyvitamin D (1,25-OH2-D), the most biologically active form of vitamin D. Then it’s off to the tissues of the body to work some magic.*

We can also get vitamin D from what we eat, though D isn’t distributed very well in natural foods. Vitamin D-rich foods include oily fish like salmon and swordfish, and egg yolks, butter and liver (Liver!! My Gram Sloan, a big chicken liver fan, was right…). Vitamin D is added to milk nowadays, of course, but even so, unless you’re a traditional Eskimo–eating a lot of fish, seal and whale blubber–it’s unlikely that your daily diet provides more than half of your vitamin D needs.

2) Sunshine: How much is enough?

Many factors go into determining how much sun exposure we require to ensure a healthy level of vitamin D in the bloodstream. Time of year, latitude, skin pigmentation, weather, air pollution, clothing and sunscreen all play a role. Basically, a fair-skinned, sunscreen-free person getting 10-15 minutes of total body exposure during the summer months will produce about 10,000-25,000 international units (IU) of vitamin D in 24 hours. So a Celtic-skinned person (such as myself) living in a nudist colony on the equator (not gonna happen) would do just fine, vitamin D-wise, from sunshine alone…until the skin cancer gets him, that is.

But all those other factors, from clothing to clouds, literally get in the way. Take the simple factor of skin pigmentation: it can take 5 to 10 times more sunlight for a dark-skinned individual than a light-skinned one to produce the same amount of vitamin D. Consider the plight of, say, a Nigerian-born child living in

On the lookout for vitamin D...

Canada. Between the short northern winter days, cold-weather clothes and dark skin, the chances of getting enough vitamin D from sunshine are pretty remote.

And that’s true of just about everyone in the United States today, too, regardless of skin pigmentation. In a 1989 study on indoor air quality, the Environmental Protection Agency estimated that the average American spends 93% of his or her time indoors. Today, with computers, electronic games, and 600 TV channels to choose from, that sun-less percentage has likely increased, to the detriment of our vitamin D stores.

So, most of us are not getting nearly enough vitamin D from sunshine or diet. What potential impact does that have on our health?

Stay tuned…

* * *

*(Vitamin D metabolism, which involves skin, liver, kidneys, bowel, bones, sunlight, diet, heat, several specialized proteins and dozens of specific chemical reactions–and which can be disrupted by things like rainy weather, or how often you wear a hat outdoors–is not a good argument for intelligent design.)


Filed under Nutrition, Science

FAQs: Is Vitamin D necessary for breastfed babies? (Part 1)

This is the first in a series of frequently asked questions I hear from parents in my practice. If you have an FAQ about children’s health, send it along!

Vitamin D: A buffness requirement

Is vitamin D supplementation really necessary for breastfed babies?

Vitamin D supplementation for breastfed newborns is a hot topic. Though it’s strongly recommended by the American Academy of Pediatrics, many parents understandably question the need for it. After all, isn’t breast milk nature’s perfect food? Aren’t we undermining breastfeeding promotion by saying mother’s milk is deficient in something? And, hey…if this is such a problem, how did the human race manage to get by without vitamin drops all these eons??

Let’s look at the issue from a number of angles and see what the fuss is all about. I’ll start with a basic Q & A and then go into more detail in future posts.

1) What is vitamin D?

Vitamin D is a steroid hormone. It belongs to the same chemical family as cholesterol, testosterone and estrogen, among many other compounds.

2) What does vitamin D do?

It was originally thought to only play a role in bone health, by helping the body absorb calcium. In recent years, though, vitamin D has been shown to play an important role in immune system functioning, both by heightening the body’s responses to invading bacteria and preventing the immune system from attacking normal tissues.

3) Where do we get vitamin D?

There are two major sources: sunlight and diet. Sunlight is the more efficient way to get vitamin D.

The good stuff

4) What happens if we don’t get enough?

Historically, the connection between lack of sunshine and rickets–soft, deformed bones–was made in the 19th century. (Pelvic bones shrunken and deformed by rickets were the cause of many deaths in childbirth in those days.) Later, a lack of vitamin D was identified as the cause of rickets. Osteoporosis, especially in women, also results from inadequate vitamin D. Recently, as vitamin D’s immune system role has become clearer, a lack of vitamin D has also been linked to a number of serious chronic conditions, such as Type 1 diabetes, systemic lupus erythematosis, and multiple sclerosis.

5) Why is there so much vitamin D deficiency these days?

It’s mainly due to decreased sun exposure and poor diet.

6) So why are breastfed babies at risk for vitamin D deficiency?

Many pregnant or lactating women don’t have enough vitamin D for their own bodies, let alone enough to build up their babies’ supply. A mother’s problem soon becomes her baby’s problem, too.

More to come…

Leave a comment

Filed under Nutrition, Science

Poor parents diluting formula: A sign of the times?

On the political chopping block?

This is a very worrisome item if you care about children and the future of this country.

Researchers at Cincinnati Children’s Hospital found that 27% of families enrolled in the federal Special Supplemental Program for Women, Infants and Children program (better known as WIC) reported running out of their babies’ WIC-supplied formula at the end of most months, and watering down the formula to get by.

That’s a very bad thing to do to a developing brain. There is ample evidence from all over the world that malnourished infants and toddlers can end up permanently damaged. Preventing that from happening is why WIC was founded in the first place.  

This doesn’t seem to trouble the members of Congress, particularly the Tea Party Republicans. The recent Congressional budget fight, which is far from over, included Republican-led proposals that could drop 700,000 women and children from the WIC program. The nutritional toll this would take on American children is appalling.

Keep that in mind next time you hear politicans babble on about poor people getting a free ride.

(P.S.: WIC is very much pro-breastfeeding. They provide formula to women who decide not to nurse their babies.)

Leave a comment

Filed under Nutrition, Politics

More on the obesity front

Candy, kids?


Breakfast quiz:

Kellogg’s Honey Smacks cereal contains how much added sugar by weight?


a)     10%

b)     20%

c)     30%

d)    40%

Answer:  Sorry, trick question. The correct answer is ‘none of the above’, because Honey Smacks is actually more than 50% added sugar by weight.

Now, you’d probably expect that from a cereal with the somewhat misleading word ‘Honey’ in its name. (Remember when they used to be called ‘Sugar Smacks’?  Ah, for those simpler, more bluntly marketed  times of yore…) But Honey Smacks is far from alone in turning breakfast into dessert.

In a study recently released by the Environmental Working Group, two-thirds of the 84 popular cereal brands surveyed exceeded federal guidelines for sugar content. And that includes 25 cereals manufactured by General Mills, which, you may recall, was a “Premier Sponsor” of the recent annual meeting of the American Dietetic Association.

Absolutely unsurprisingly, cereal manufacturers are fighting the federal guidelines–which are voluntary, by the way–tooth and nail. I don’t have a quote from the manufacturers to give you, but if I did it would no doubt run along the lines of cursing the socialist nanny state the U.S. has become,

...and sugar for all.

and reasserting the God-given right of American parents to turn their children into diabetics before they are old enough to vote. (Cue the flags.)

Yes, parents can certainly read the nutrition facts printed on the cereal box and make intelligent nutrition choices, but wouldn’t it be better if they didn’t have to wade through a minefield of unhealthy choices (masterfully marketed to their kids) in the first place? The sad fact is that cereals such as these are mainstays in the diet of many American school kids, and in many areas of the country it’s not easy to find healthy alternatives.

Unfortunately, the Environmental Working Group didn’t include a list of low-sugar cereals, which would be a helpful aid to harried and hurried parents at the market. I’ll try to dig one up and report back.

Do you have a healthy cereal alternative you’d like to recommend?


Filed under Nutrition, Obesity

Who can you trust anymore? Maybe not the American Dietetic Association…

Ay-yi-yi! First we had Congress designating pizza as a vegetable, and now this:

Words escape me...

The American Dietetic Association–the self-described “world’s largest association of food and nutrition professionals” (and whose website,,  proclaims that it provides “Food and Nutrition Information You Can Trust”)–is apparently transforming itself into a shill for Big Food.

Need proof? Look no further than the ADA’s recent annual conference, as reported by Michele Simon, a public health lawyer specializing in food industry marketing and lobbying tactics:

The top-paying sponsors, whom ADA called “partners,” were Coca-Cola, Aramark, the National Dairy Council, and Hershey (their “Center for Health and Nutrition” – really). “Premier sponsors” included PepsiCo, Mars, and General Mills.

Among the conference’s many panel discussion and didactic sessions were topics like “How Risky is Our Food? Clarifying the Controversies of Chemical Risks.” The speakers at many of the sessions had undisclosed food industry ties, despite ADA rules that require disclosure of conflicts of interest. (Those “risks,” as you might suspect, aren’t nearly as bad as those lying environmental radicals say they are…)

Fortunately, some Registered Dietitians are fighting back:

During the Q&A, several frustrated attendees challenged the presenters–the only time the audience heard any opposing viewpoint. Several who spoke up are members of the Hunger and Environmental Nutrition Dietary Practice Group, which represents a growing number of RDs who are challenging ADA’s corporate ties and making inroads, slowly but surely.

It’s pretty clear that some powerful/ruthless corporate forces are behind the push to feed dreck to our kids. The ADA needs to do the right thing and cut ties with those funders who don’t have the best interests of children at heart…especially the ones who are actively undermining children’s health.

1 Comment

Filed under Nutrition