USDA Dietary Guidelines: Un-“d”ependable

Consuming large quantities of any one vitamin can cause serious health problems. How serious those health problems are depends on the vitamin. For instance, an overconsumption of water soluble vitamins like vitamin C lead to relatively minor problems like stomach pain, but an overconsumption of fat soluble vitamins often leads to more serious health issues like birth defects in expectant mothers, the damaging of internal organs due to calcium crystalline formation, or nerve damage.

In short, you don’t want to mess with fat soluble vitamins – like by boosting your vitamin D intake ten times the recommended daily amount. But believe it or not, that’s exactly what researchers recommend growing boys and girls do.

Currently, the daily recommended dosage of vitamin D is approximately 200 IUs for children. But the researchers had a sneaking suspicion that because children grow at a rapid rate, particularly in their pre-teen years, they could probably use a lot more. Working from this under assumptions, they gave 25 boys and girls massive doses of vitamin D – 14,000 IUs of vitamin D over a week’s – which is ten times the recommended amount. Now if this were a one time dose, there’d be minimal side effects if the kids showed signs of vitamin toxicity. Overdosing on vitamin D in the short term can cause nausea and abdominal cramping. But these researchers essentially threw caution to the wind and supplemented the pre-teen and teenage crop of kids with 14,000 IUs of vitamin D for eight weeks!

As the researchers suspected, the 15 boys and 10 girls displayed no signs or symptoms of vitamin D toxicity. Secure in the knowledge that the high dosage would not cause short or long term harm, the researchers expanded their pool of participants to 340 boys and girls and supplemented half with 2000 IUs of vitamin D per day and the other half with 1400 IUs per day for a year (both well above the RDA of vitamin D). The result? Only those supplemented with 2000 IUs per day maintained healthy levels of vitamin D in their blood stream (for adults, a healthy vitamin D level is between 90 and 100 nanomoles per liter of blood).

The research is published in the Journal of Clinical Endocrinology & Metabolism and was conducted by a team of researchers from American University’s Beirut Medical Center in Beirut, Lebanon.

I suppose it’s true, the researchers were taking something of a risk when they supplemented young kids with potentially toxic levels of vitamin D, but it’s been fairly well known for a while now that the recommended vitamin D levels for kids – and adults – are woefully underestimated (current recommendations suggest adults get 400 IUs per day and those over 70 years of age 600 IUs per day). What it will take to get the USDA to update these recommendations is anyone’s guess, but you’d be foolish to use the USDA as a sound guideline for nutrient consumption. Studies like the aforementioned, as well as a 2006 study published in American Journal of Nutrition suggest increasing one’s vitamin D intake. The 2006 study doesn’t go so far as to suggest increasing intake ten times what’s recommended, but at least 700 IUs per day, preferably 1000 IUs per day.

Figuring out how many IUs equals how many micrograms or milligrams takes far too long. Just know that whatever amounts of vitamin D you’re getting now, you can probably stand a whole lot more (unless you spend each and every day outdoors in the hot sun). As serious as the side effects of too much vitamin D can be, too little can be just as serious, if not more so, causing things like rickets, osteomalacia and osteoporosis.

If you’re levels are low, spending more time outdoors, choosing fortified organic milk and soy milk as well as serving up generous portions of salmon more frequently will get your vitamin D levels up in no time.