Wednesday, September 16, 2009

The Obesity "Epidemic" and Nutrition

There has been a lot of talk and newsprint about the obesity "epidemic" that is occurring, but I feel that certain facts have been ignored, as well as certain principles of human behavior. Whenever patients tell me that doctors don't know much about human nutrition, I generally comment that neither does anybody else. There have been very few double-blinded studies about the effect of nutrition on human health and well-being, but that doesn't seem to stop people from being more certain about human nutrition than the facts will allow:

1) No one knows how many meals a human should eat each day: one, six, or whatever.

2) No one knows at what time of the day the largest meal should be eaten, (but if you eat within 2 hours of bedtime you increase your risk of reflux esophagitis).

3) If you eat only vegetables, you will die from pernicious anemia, aka vitamin B-12 deficiency, since vegetable cells contain NO vitamin B-12; vitamin B-12 is is needed for animal cell DNA synthesis, and not for vegetable DNA.

4) Nobody smiles in a vegetarian restaurant, but everyone looks ecstatic at a steak restaurant such as Peter Luger's.

5) The only vegetables that seem to benefit human health when added to the diet are alcohol (beer, wine or whiskey), dark chocolate, olive oil (the Mediterranean diet), and the bark of the willow (salicylic acid, which Bayer transformed into aspirin).

6) No one knows how much water/fluids a human should drink each day, but the general consensus is a minimum of 0.5 liters, since that is the urine volume required to excrete the products of oxidation in maximally concentrated urine.

7) In a hospital, the minimum IV should be D5/0.5NaCl with 20 meq of KCl at 125 cc/hr, and then adjust to the patient's condition.

8) Fat cells require cholesterol and preferentially absorb insulin, so if you are a diabetic or have a cholesterol problem, you should lose weight.

9) Cholesterol does not increase cholesterol, so egg yolks are OK, and, in fact, eggs have about the highest protein per gram of any food.

10) If you do not have high blood pressure and are not diabetic, then salt and sugar should cause you no problem.

11) Almost all my patients who on oral medicine for diabetes cannot/will not lose weight, even after I tell them that a 20m pound weight loss will probably (temporarily) cure their diabetes.

12) As you get older, your metabolism slows up, and your blood pressure, cholesterol and fasting blood sugar generally increase.

13) Most women find it impossible to lose the last 5 pounds necessary to get down to their pre-pregnancy weight.

14) Most men gain at least 10-15 pounds the first year they work or get married, in the first case from lack of exercise (8-10 hrs/day behind a desk), and in the second case from an increase in calories consumed at dinner.

15) Cigarette smoking increases your metabolism and decreases your appetite, so most men gain 10 pounds the first year they quit smoking and most women gain 15.

16) And this is key: The first pleasure all humans got was from being fed, either at their mother's breast or from a bottle. The first desire to be fulfilled was that created by hunger. Therefore, it feels good to eat, and it is difficult to deny yourself this fundamental pleasure and to feel hungry, which you must do in order to lose weight. The first time a woman's dress goes from size 6 to size 8, or a man's belt from 32" to 34", they rarely say "I must lose some weight". It has nothing to do with not knowing how many calories they are eating, or doctor-patient information, or lack of electronic medical records. Most patients don't care enough about how they look after gaining 10 pounds, or believe that there is enough increased health risk from added weight to lose the additional pounds. Men actually are less stressed by their appearance when overweight than are women: When a woman looks full face into a mirror, she sees the added weight that went to her hips, but when a man looks in a mirror the same way, he barely sees the added weight that went to his belly.Losing weight means being willing to suffer present pain for future gain, and the human brain is not geared to worry about the future, but rather to fasten the seatbelt 10 seconds before the car hits a brick wall. The same comment about future gain also holds true for exercise, but the average patient finds it much easier to exercise than to lose weight.

17) I also think the reason that almost all humans love ice cream is that it is rich in sugar and fat, just like mother's milk.

18) Don't you think that by the time he/she is 7 days old, a baby is addicted to sugar by Pavlovian conditioning: whenever he/she is hungry (or whatever is felt), this discomfort is assuaged by a warm sweet fluid, so that the baby associates warmth (chicken soup?) and sweets with a sense of comfort and well-being. It's difficult to see how an external message can easily overcome this dependence.

19) Final observation: based on my informal questioning of my patients, the majority of adults who loved chocolate ice cream as a child can curl their tongue (I can!), while the majority of patients who did not like chocolate ice cream cannot. I wonder what the genetic linkage is. I personally thought that my friends who preferred vanilla ice cream to chocolate could not have possibly tasted the same chocolate flavor that I did.

Saturday, September 5, 2009

Radiation, X-rays, Medicine, and Cancer

The question of the relationship between radiation, X-rays, cosmic rays, (radioactive) radon gas, and cancer is a murky one, and there are many unanswered questions. In some cases, exposure to radiation gives the patient an increased lifetime risk for cancer, and for reasons unknown to medical science, the risk for women is greater than the risk for men. Because of the very long time delays that can be involved (up to 45 years has been recorded), it would appear that radiation is a cancer potentiator, rather than a direct inducer.(But radiation itself can be an inducer for a cell that has already been potentiated.) In the cases (Hiroshima, Chernobyl) where a direct and short time correlation has been observed, it is probable that the intensity of the radiation is also important. We know that high energy, high intensity radiation is lethal to humans, and lower intensity radiation is lethal to cancer cells. We also know about radiation sickness. We have a rough idea of the lethal dose of radiation (which is different for alpha rays, beta rays, photons (gamma rays), neutrons, and cosmic radiation). We know how much radiation shielding astronauts need to keep them alive.

We do not know, and will never know, the LD50 dose for humans for any type of radiation. We cannot even measure human radiation exposure. The unit called the Sievert is used, but the Sievert depends on the type of radiation, the energy, and, most important of all, the amount of radiation energy absorbed by various tissues, and this latter term can only be estimated (and very poorly, at that) from animal studies. We also know that we are missing some scientific factor: The residents of Denver dwell 5,000 feet higher than the residents of NYC, and therefore have one mile less of atmospheric shielding from cosmic rays. How is it then that Denver residents do not have a significantly higher rate of cancer than do Manhattanites?

There was a recent article published in JAMA detailing the increased amount of radiation we are all getting over our lifetime from X-ray studies. In fact, the U.S. gov't has officially classified radiation as a carcinogen. Why is it then that no patient is ever given a release form to sign than delineates the estimated immediate and lifetime personal carcinogenic risk from the proposed X-ray study? (I once tried to generate and have my ER patients sign such a form, and I was immediately told by the chairmen of Radiology and Medicine to stop.)

Thirty years ago, when I was a physics professor, I started to do some experiments with a colleague of mine from Princeton. Since he had a joint appointment with Princeton Physics Dept. and the Princeton Plasma Physics Lab, which meant that he also worked on the Stellarator, our research was classified (and still is, for all I know). We then co-opted a physicist at Oak Ridge Nat'l Labs for good radioactive sources. We were trying to see if there is a minimum radiation dose below which there is NO cancer risk. The belief now as well as then was that there is not, and that there is no minimum safe dose of radiation. We were unable to come to a definite conclusion. We could not determine whether or not a certain straight line on a graph passed through the origin.

The universal fear of radiation is so great that MRI was initially called by its correct name NMR (Nuclear Magnetic Resonance), but NMR was changed to MRI so as to not scare patients away from the MRI. We could greatly decrease food poisoning and contamination with germs and bugs by subjecting wheat, fruit, etc., to killing levels of radiation, but again, the public is so fearful of the possible consequences of radiation that Congress has never passed a food-radiation enabling law, and we can therefore expect future lethal food outbreaks similar to the E. Coli in hamburgers. The one time we should have been fearful, we were not, and many women who licked camel's hair brushes to make a finer point before painting the numbers on a wristwatch with a radioactive chemical developed mouth and jaw cancers.

I guess this blog is written with mixed emotions, and no firm purpose. As a physicist I have the greatest respect for the dangers of radiation, and as a physician, I know its many beneficial uses. I wish we all knew more!