Archive for March, 2010

Shifting Focus From Single Nutrients to Dietary Patterns

March 11th, 2010

A recent article came out reporting on a study that found no link between saturated fat intake and heart disease. The study they are referring to is a Meta-Analysis, where researchers find a number of studies on a topic and come up with a general consensus on the major findings  the chosen studies have in common. This particular analysis involved 21 studies, looking at a total of 347,747 subjects, followed for 5 to 23 years. Basically each of these studies followed these people for many years, tallied how many of them died from heart disease, and then checked to see if those people ate more saturated fat than the others. In other words, they looked to see if saturated fat intake was associated with heart disease. The authors said that in this specific study, there is “no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD (coronary heart disease) or CVD (cardiovascular disease).”

These findings are interesting but don’t really say much. First of all, when researchers do a meta-analysis, how do we know what studies they excluded from their analysis. Surely there are more than 21 studies looking at the relationship between saturated fat and heart disease. Secondly, we must assume that the studies chosen were critically analyzed for common flaws in the designs of these experiments, and those with errors in their design were not chosen for the meta analysis.
Finally, and most importantly, the study simply looked for an association. Not a cause. If  this study did in fact find a relationship between saturated fat intake and heart disease, it means nothing about what caused the heart disease. People who eat more meat may be less educated or exercise less; they may eat less fruits and vegetables or smoke more cigarettes. Identifying saturated fat as the culprit is not possible.

Which brings us back to the article. How is the average person supposed to know what is healthy  when daily articles give conflicting advice. And who knows what obscure study a researcher chose for a story, and whether the researcher is qualified to analyze the story accurately. The Doctor in the article says “the thinking on diet and heart health is moving away from a focus on single nutrients and toward ‘dietary patterns.’” Maybe this advice is more practical, since after all, foods are made of many nutrients, and focusing on one of them may lead to trouble.

When using PhotoCalorie to monitor your diet,  focus less on the individual nutrients and more on the pictures. Maybe try increasing your fruits and vegetables, and decreasing your big macs and lollipops!