Archives for: February 2009, 20
One Little Sentence Vit D AWsec
The pile of books next to my favorite reading chair keeps getting larger as I find myself taking every health book out of my local library. I am not much of a reader for pleasure but I do enjoy reading for information. The more health or medical related the more I like it. I try and take time out each day to read from some of the books.
It was about a week ago that I came across this quote from a book entitled:
"Feed Your Genes Right: Eat to turn off Disease Causing Genes and Slow Down Aging", by Jack Challem.
"In addition, grain consumption reduces vitamin D absorption." Page 195.
I was intrigued because of a recent discussion on the Chat Right Forum. A few of the women on the forum had had their Vitamin D levels tested and were taking supplements. Low vitamin D has been implicated in some forms of cancer so certainly it would be important to supplement if your vitamin D levels are low.
I then went to the internet to see if I could find any more information about the authors source of this sentence.
I found the following from an interview with Loren Cordain, PhD and author of the "Paleo Diet". Cordain is a proponent of returning to man's original ancestral diet, a hunter/gatherer diet.
"Robert Crayhon (interviewer): How do they (grains) alter vitamin D metabolism?
Loren Cordain: Epidemiological studies of populations consuming high levels of unleavened whole grain breads show vitamin D deficiency to be widespread. A study of radio-labelled 25 hydroxyvitamin D3 (25(OH)D3) in humans consuming 60g of wheat bran daily for 30 days clearly demonstrated an enhanced elimination of 25(OH)D3 in the intestinal lumen. The mechanism by which cereal grain consumption influences vitamin D is unclear. Some investigators have suggested that cereal grains may interfere with the enterohepatic circulation of vitamin D or its metabolites, whereas others have shown that calcium deficiency increases that rate of inactivation of vitamin D in the liver. This effect is mediated by 1,25 dihydroxyvitamin D (1,25(OH)2D) produced in response to secondary hyperparathyroidism, which promotes hepatic conversion of vitamin D to polar inactivation products which are excreted in bile. Consequently, the low Ca/P ratio of cereal grains has the ability to elevate PTH which in turn stimulates increased production of (1,25(OH)2D) which causes an accelerated loss of 25 hydroxy vitamin D."
This is in technical terms, but basically it means that a diet high in grains will keep vitamin D from being absorbed properly this is exactly what I had read in Mr. Challem's book. Sadly the american diet is about 70% grains, the current food pyrimid recommends 6-11 servings of whole grains per day. Americans are actually encouraged to eat whole wheat products as part of a healthy cancer prevention diet.
From what I just read it would be safe to say that the standard american diet keeps us from properly absorbing vitamin D, which puts us at greater risk for cancer.
Now wouldn't it have been good if the doctor who gave those women the vitamin D supplement also discussed the importance of how grains effect vitamin D absorption?