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Are we consuming too much Vitamin C?


Via a Google Reader shared item from Patri Friedman titled Vitamin C Abolishes Endurance Training Effects. The post is just a synopsis of a study that demonstrated that Vitamin C has a negative impact on training for endurance. That we should be training for endurance at all is a topic often derided by various paleo gurus, but the somewhat tangential snippet below is what really caught my eye. It immediately makes me wonder, how much Vitamin C should we be consuming in our diets? Fruits and vegetables are frequently touted as the end-all be-all of nutrition, but most all of those foods have a lot of Vitamin C, which is an antioxident we arguably don’t need much of.

A mere cup of chopped broccoli has 135% of the daily recommendation, which is 90 mg, so 120 mg (Vit C rec. info). And who eats just a cup of broccoli? Further, what about all the other sources we’d get C from in a day?

Who would have thought maybe the colorful fruits and veggies are actually harming our health? Maybe Peter at Hyperlipid has it right. It’s worth further investigation.

Here’s the bit from the Mangans blog:

As noted before on this blog, glutathione is by far the most important antioxidant, and it’s made internally from amino acids. Other antioxidants, as can be seen here, can hamper its production.

Our paleolithic ancestors would probably have been ingesting only small amounts of vitamin C, so any dose larger than say, 100 mg, must be considered quite unnatural. That is not to say that megadoses of vitamin C may not be useful in certain medical conditions, but overall it seems best to avoid that. Many holistic practitioners recommend doses of several grams a day, which could be positively harmful to health. At the least, we can say that athletes should take small doses if any.

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Get Your Vitamin D Checked: Why And How?…b9aded0752f2131

After my commentary is a nice round-up of Vitamin D benefits from LifeSpotlight (as well as a link to where you can get a test done on your levels).

And now for an obligatory anecdotal “Vitamin D rocks” story:

Just last week my pregnant, dark-skinned (Read: harder to get Vit D) wife came down with a pretty strong cold (and it may have been the flu). For a few days, I seemed to totally avoid it despite taking care of her, sleeping in the same bed, and not taking any particular precautions. About five days into her sickness, I woke up with a scratchy throat and mild congestion. Note: I had previously been supplementing about 5,000 IU of Vitamin D3 a day (Two Carlson Lab Vit Ds plus another 1,000 IU or so from some Calcium vitamins).

On the initial cold symptoms, I immediately upped the dosage to two doses of 10,000 IU per day (So 10 of those tiny little Carlson pills per day total).

Twenty-four hours later, the scratchy throat was still there but it had not gotten any worse. I continued supplementation and after three days of mild scratchy throat and extremely mild congestion, it was gone.

Obviously this is anecdotal, but this has never been the normal progression of a cold for me. The scratchy throat always develops into an all out snotfest within 24 hours and then lasts for days if not more than a week.

So I’m a big believer in Vitamin D at this point. Don’t supplement in these winter months at your own risk.

The clip:

For starters, height and body fat in adolescent girls is affected by vitamin D status:

Approximately 59% of subjects were 25OHD [vitamin D3] insufficient (≤29 ng/ml), and 41% were sufficient (≥30 ng/ml). Strong negative relationships were present between serum 25OHD and … measures of visceral and sc [subcutaneous] fat… In addition, weight, body mass, and imaging measures of adiposity at all sites were significantly lower in women with normal serum 25OHD concentrations than women with insufficient levels. …there was a positive correlation between 25OHD levels and height.

The demarcation line of “sufficient” is quite low as well, so no telling what we’d see with people that have levels in the 40, 50, or 60 ng/mL range.

It’s been found before that higher levels of vitamin D correlate with better breast cancer outcomes. Now we know why: Vitamin D Found To Stimulate A Protein That Inhibits The Growth Of Breast Cancer Cells

Calcitrol, the active form of vitamin D, has been found to induce a tumor suppressing protein that can inhibit the growth of breast cancer cells

Athletes, muscle power is increased by vitamin D (at least for girls).

After controlling for differences in the girls’ body weight, the girls with the highest vitamin D levels had the highest jump speeds, jump height, power and force.

Want to think clearly in old age? Get enough vitamin D

The study found that as levels of Vitamin D went down, levels of cognitive impairment went up. Compared to those with optimum levels of Vitamin D, those with the lowest levels were more than twice as likely to be cognitively impaired.

And if you want a cold or the flu, keeping your vitamin D levels low will help.

In the largest and most nationally representative study of the association between vitamin D and respiratory infections, people with the lowest blood vitamin D levels reported having significantly more recent colds or cases of the flu. The risks were even higher for those with chronic respiratory disorders, such as asthma and emphysema.

Here are a few more peculiar things vitamin D supplementation has done for Dr. William Davis’ (of The Heart Scan Blog) patients.