Reading the September issue of the scholarly journal, Annals of Internal Medicine, a monthly publication of the American College of Physicians, I came across a marvelously detailed article on low-carb diets. It was a joint effort by the Harvard School of Public Health and the National University of Singapore and examined the results of two huge, long-term projects. It was followed by an editorial review as major articles frequently are in the Annals; the groups reviewing the article were from Duke and the Durham VA Medical Center (staffed by Duke professors in my day there).

The Nurses Health Study prospectively followed 85,168 women, aged from mid-30s to just under 60 initially, for twenty-six years. The Health Porfessional's Follow-up Study did the same for a group of 44,548 men (podiatrists, optometrists, pharmacists, dentists and veterinarians, but not physicians), aged 40 to 75 years initially, for twenty years.

The researchers conclusions were that eating a low carb diet from animal sources led to a higher mortality risk whereas the opposite was true for eating a low carb diet based on vegetable sources.

So far, things seemed reasonable to me, but then the reviewers analyzed the article and tore it apart in many respects. It was the best of times; it was the worst of times, or to paraphrase, it wasn't the best of studies; it wasn't the worst of studies.

The first problem was this wasn't a controlled clinical trial, but just an enormous observational study. Then there were caveats about extra risk factors: sure the men who ate the most animal-based fat were at greater risk for heart-disease deaths, but they also smoked more and exercised less. And low-carb wasn't exactly really low carb; the group eating the least carbs per day really ate a fair amount (nearly 40% of their calories as carbs). And the participants in these studies aren't exactly representative of the broader (no pun intended) US population and weren't put on specific diets at all.

So what did I end up with? Just what I've been saying all along. Eating more veggies and less red meat, exercising more, not smoking...all those make sense. Moderate carb, low carb, this diet, that diet...none of those ideas has been convincingly proven. Actually low-fat hasn't been shown to reduce health outcomes either.

So eat sensibly, try cutting back on red meats and processed meats and be sure to eat your veggies (and fruits). Didn't Mom always say that?

An interesting article appeared in last Wednesday's Journal of the American Medical Association. It reported a National Cancer Institute surveillance program which covered a large segment of the American population (about 25% of us) and reviewed over 39,000 cases of stomach cancer. The rates of new cases of this frequently fatal disease declined in almost all age groups except for while adults age 25 to 39 where it climbed almost 70%.

Now this could be just a statistical issue and the overall rates were still quite low (1 in 200,000). But, on the other hand, the one major association found was to diets, especially those high in salt and foods preserved with salt and low in fresh fruits and vegetables.

The study was looking at cancer in the "lower stomach," sometimes felt to be caused by chronic infections with H. Pylori, the same bacteria that's associated with ulcers. This is as opposed to disease in the cancer in the "upper stomach" associated with reflux disease.

Most other adults in the age range studied (25 to 80) had a clearcut decrease in rates of developing stomach cancer and black adults shared in this decrease. The authors noted that historically the incidence of this form of cancer has been higher in parts of the world where foods are often preserved with salt. Those rates have declined in many countries along with decreased rates of H. Pylori infection and the overall decrease in U.S. rates was certainly not unexpected.

We're left with an actual increase in one group. It will be further investigated, but the authors noted that salt intake has been going up in Americans in general and wondered if altered eating patterns were the culprit in the young adults in the study.

Hmm.. I've written before about our excess salt intake (for some of us it's more than twice what is recommended)  and suggested we could lower high blood pressure incidence with all of its potential for devastating consequences if we were to cut down on the salt, both by adding less and by eating less of those prepared foods that are high in sodium content.

Now we have one more reason to spurn the salt shaker and shop wisely for more fresh fruits and vegetables.

I read The Economist regularly, but was unaware, until I purchased the book, An Edible History of Humanity, that Tom Standage, listed as the magazine's business affairs editor, was also an author. I've just started leafing through his 2009 book, having finished reading one of the two book club selections I needed to get through by next week. But even perusing the book over a few minutes, I've already seen it connects to a number of topics I'm interested in.

One of those is the ongoing controversy about genetically modified food. Early in Standage's book, he discusses the progression of teosinte, an ancestral form of maize, to modern corn. It seems clear to me that human selection of which crops had their seeds spread was responsible for this. The author notes that a cave in Mexico has a series of ancient cobs that vary from half an inch to eight inches in length and talks of the high likelihood that farmers of the past would have deliberately chosen those mutated maize varieties that produced larger ears.

So we've been fiddling with our food crops for a long time. Well and good in many or even most instances; basically I have no problem with the concept . But Standage also discusses the 1845 Irish potato famine where an over-dependence on a single food and a devestating crop failure caused by a fungus infection, led to a million deaths.

So on the one hand I often approve of our modifying our food sources, but, as I've mentioned in previous posts, I personally think some of the heirloom varieties of vegetables which are available in our local farmers markets just plain taste better than their super-market cousins. They also may protect us in a fashion by their being different.

I don't want us to become reliant on a single variety, a solitary kind of almost any food crop. The need to produce more corn, more tomatoes, more potatoes, may have been one factor leading to the highly productive mega-farm concept of agriculture, but I worry that it also exposes us as a country, or even as a species, to the risk of famines if a new vegetable disease and/or climate change wipes out a particular strain of a crop or multiple crops.

Is this at all a realistic issue? We now have highly developed, well-connected sources of production and shipping of food items, but we also have a burgeoning human population and the threat of global warming, derided by some, but strongly concurred with by many.

I'm in favor of keeping multiple food sources and expanding our choices whenever possible.

That's enough for today; I realize I've tried to connect some dots that may seem isolated from each other, but I think they're well worth cogitating over.