Thursday, June 10, 2010

Five Diseases Caused by Nutritional Deficiencies

Yesterday I needed to run a last-minute errand to Skowhegan (and saw Lakewood Theater's hilarious production of Drop Dead, which was worth the trip — it closes Saturday, so check it out if you can). The drive takes just over an hour each way, and my company was the audiobook of SCURVY: How a Surgeon, a Mariner, and a Gentlemen Solved the Greatest Medical Mystery of the Age of Sail by Steven Bown.

The book is fascinating and full of gory details about naval life, obsolete medical practices and theories, and the history of science. But I can't read medical histories, however entertaining, without a little bit of hypochondria — so for the past few days I've been especially careful about my Vitamin C intake, and thinking about what other essential nutrients might be missing from my diet. Lord knows I wouldn't want to get any of these diseases.

1. Scurvy. Scurvy, as Bown makes clear in his book, is an exceptionally nasty way to die. The lack of Vitamin C (ascorbic acid, which means "acid that prevents scurvy") prevents the body from manufacturing collagen, the substance that holds us together. Gums rot, injuries don't heal, the skin can't repair itself, and eventually even broken bones that have mended come apart again. The body rots and is unable to heal, and scurvy victims eventually bleed to death when the very walls of blood vessels start to come apart. As little as 6.5 mg of Vitamin C a day can prevent scurvy. A medium orange has 50 mg, and a 100-mg serving of broccoli has twice the minimum daily requirement, as long as it's not overcooked. Boiling destroys the vitamin.

2. Beriberi. Beriberi is caused by a thiamine (B1) deficiency, and in developed nations tends to be a disease of alcoholics. "Wet beriberi" affects the cardiovascular system, and can look like congestive heart failure. Victims have shortness of breath at night and after activity, an increased heart rate, and swelling of the legs. "Dry beriberi" affects the nervous system; victims experience tingling and numbness, weakness in their legs, confusion, mental difficulties, memory loss, twitching, and pain. Wernicke-Korsakoff syndrome, related to dry beriberi, is a tragic disorder that destroys its victims' ability to create new memories. A rare genetic disorder interferes with the ability to absorb thiamine, but most people need only between 1.1 and 1.5 mg of thiamine daily to prevent beriberi. Meats, eggs, whole grains, nuts and legumes are all good sources of thiamine. Milling and bleaching destroy thiamine, but white bread in this country is almost always thiamine-fortified.

3. Pellagra. Doctors refer to pellagra's symptoms as "the three D's": diarrhea, dermatitis, and dementia. Its cause is most frequently a deficiency of niacin (B3), but it may also be caused by deficiencies of the amino acids tryptophan or lysine, or by excessive intake of leucine. Pellagra was once endemic among populations that relied on maize as a staple food, and was so prevalent in the American South in the early 20th century that an entire hospital in Spartanburg, SC was dedicated to its treatment and study. Pellagra is still common among refugee populations, and in impoverished regions of Africa, Indonesia, and China. A small amount of brewer's yeast provides enough B3 to prevent pellagra; other good food sources are meats, whole grains, green and orange vegetables, nuts and legumes.

4. Rickets. My own grandfather McLaughlin had rickets as a child, growing up in the slums of Charleston, SC. It's a disease of slums and workhouses, caused by a deficiency of Vitamin D and/or calcium and/or phosphate. Bones soften, weaken and bend; my grandfather's shin bones were visibly bowed, although he was tall and had excellent teeth, unusual for victims of rickets. Vitamin D is the "sunshine vitamin," but most people in industrialized countries don't spend enough time outdoors to get a full dose, so food sources are also important. Fish, liver and fortified dairy products all provide significant amounts of Vitamin D. Vegetarians have to be especially careful to get enough Vitamin D, and may need to take a supplement.

5. Night blindness and xerophthalmia. Deficiencies in Vitamin A cause eye problems ranging from night blindness to complete blindness. Xerophthalmia is a fancy name for a medical condition in which the eye fails to produce tears. I've seen television ads for a treatment for "chronic dry eye," and wonder how often that disorder is simply an undiagnosed Vitamin A deficiency. Fortified dairy products provide some Vitamin A, but how many of us drink five glasses of milk (or the equivalent) a day? The best food sources of Vitamin A are dark green leafy vegetables and orange fruits and vegetables — carrots, cantaloupe, butternut squash, etc. Megadoses of synthetic Vitamin A (not from food sources) are the only recognized medical therapy for retinitis pigmentosa, but because Vitamin A is fat-soluble, high doses can be toxic. It's safest to get this vitamin from natural food sources. Too many carrots might turn you yellow (it happened to me when I was little, according to family legend), but they won't poison you.


Anonymous said...

Ricketts is actually resurgent in poor urban neighborhoods in the U.S. The problem appears to be that kids spend all their free time indoors watching TV and playing video games -- in part because their streets are not safe -- and that parents switch their kids from formula to soft drinks at ages as young as six months, giving the children almost no milk.

-- Ed

JIM LAMB said...

I always told your Mother that beef and beer were the best food for a balanced diet, but she preferred fish and gin and I love dark vegetables.
I never did care for Donald Duck. My favorite cartoon character is Scrooge McDuck and i try to duplicate his money hoard.
Who would make the Brown Pelican an endangered species? To those who spend their time on the waterfront and the sea that would be the same as making the Norwegian grey Rat a protected species. I have seen pelicans attack swimmers when they felt the swimmers were interfering with the fish. Commercial and sport fishermen will shoot pelicans when they thing they can get away with it.

Anonymous said...

Hi, Where did you find your information on Beriberi? I am doing a research project on the disease but have had no luck in locating sources. If you could let me know where you found yours I would be very grateful! Thank you for your time.

Anonymous said...

Hi, Where did you find your information on Beriberi? I am doing a research project on the disease but have had no luck in locating sources. If you could let me know where you found yours I would be very grateful! Thank you for your time.