Question: Snus, prepared from ground tobacco leaves, is a form of snuff that's usually tucked inside the cheek, where its nicotine payload can be slowly absorbed across the mucous membranes of the mouth. Snuff is generally regarded as harmful—in South Asia, for example, it's associated with a higher risk for mouth cancer. Is snus lower risk?
New research: That is the question examined in this recent Lancet paper. The researchers followed more than 125,000 Swedish construction workers, for 12 to 26 years, who were nonsmoking users of snus. They found no increase in oral or lung cancers, compared with nonsmokers who did not use any form of tobacco. But they did find an approximately double risk of developing pancreatic cancer, resulting in about 40 more cases of this disease in the 125,000 snus users. Other studies of snus users in Sweden show only tiny increases in heart disease and stroke, two conditions that are significantly higher in cigarette smokers. It would appear, then, that snus—though not risk-free—is safer than smoking.
Implications: Another Lancet paper examined whether introducing snus in Australia (where snuff is illegal, but cigarette smoking is not) would lead to an increase in tobacco use. The authors come out pro-snus: They argue that if snus were made legal, between 14 and 25 nonsmokers would have to start using to offset the gain in average life expectancy from every one smoker who quit and switched to snus.
Conclusion: Currently, more than 5 million people a year die worldwide as a result of tobacco use—in most developed countries, it's the cause of about one out of five deaths. The chronic illnesses associated with it are also terrible. So, these papers on snus put public-health people in a quandary. Should we promote a less hazardous tobacco product? If the goal is to reduce the harm done by tobacco, snus seems a pretty good choice. And yet I find it very hard to get the words out of my mouth. Which leaves me with a troubling question: Are doctors like me—blocked by prejudices from making rational choices—contributing to the harms caused by smoking? I'd better reform my ways.
Question: When we think of the effects of severe malnutrition, we usually think of weakness, stunted growth, and perhaps apathy and a diminished ability to learn. It's less well-known that nutritional deprivation—in particular, protein- and calorie-deficiency—have another pervasive and insidious effect: a diminished immune response that increases susceptibility to infectious disease. Why, exactly, does malnutrition cause a poor immune response?
New research: A recent paper provides some answers. Mounting a strong immune defense requires the body to generate an increased number of the white blood cells that engulf and destroy invading organisms, by jump-starting the production of antibodies—proteins that bind to and inactivate bacteria and viruses. Making new cells and synthesizing proteins require energy that seriously malnourished people simply do not have to spare. Without these defensive cells and antibody molecules, they are less able to control infections once they've started. Also, people whose protein intake is deficient don't have an adequate source of amino acids, including the amino acid arginine, which has special importance for good immune function because of the role it plays in controlling the release of cytokines, chemicals involved in immune defense.
Also: Other food ingredients, like vitamin A and zinc, additionally help enhance response to disease. Finally, the growth of certain bacteria is inhibited by the ingredients in a replete diet. For example, the folklore that undernourished people are at greater risk for developing tuberculosis is true. Animal studies going back more than 50 years suggested this, and recent human research has shown that a cholesterol-rich diet significantly improves the rate at which TB patients respond to treatment.