Milking Research, Again: Science Is Dashed in New Dairy Ads
The dairy industry has again stepped over the bounds of responsible advertising, according to a PCRM complaint lodged with the Federal Trade Commission in February. New advertisements, funded by the National Dairy Council and its allies, wrongly imply that dairy products are a good way to cut high blood pressure.
The ads cite the Dietary Approaches to Stop Hypertension (DASH) study, which found that, indeed, diet changes do lower blood pressure, at least to a degree. The problem is, the study did not test the effect of dairy products. It tested a combination diet including plenty of vegetables, fruits, and grains, and cutting back on meat, snacks, sweets, and fat. Dairy products were included in the diet, but their effects were not isolated for testing. The DASH study was largely inspired by previous research showing that vegetarian diets lower blood pressure.
In dietetic journals during fall 2000, full-page dairy ads ran the headline, "Dairy Makes the Difference in DASH," suggesting that milk is what lowered blood pressure in the study participants; all the other dietary differences—extra vegetables, less meat, less fat, etc.—were unimportant. The ad campaign was particularly brazen since the DASH investigators had already gone on record in medical journals, pointing out that no single food product could take credit for its effect. The researchers estimated that about half of the blood-pressure-lowering effect was due to fruits and vegetables, whose high potassium content is known to reduce blood pressure. The remaining half, they wrote, could not be attributed to any single food or nutrient, since the diet differed in many respects from a typical American diet. Eliminating meat from the diet is known to reduce blood pressure, and cutting down on fat also contributes to lower pressures. Calcium-rich foods, including dairy products, do seem to reduce blood pressure, at least in some research studies, but the effect is very small, approximately 1 mmHg.
In 1997, David McCarron, a dairy industry representative, wrote to the New England Journal of Medicine, suggesting that dairy products deserved a major part of the credit for the DASH diet's blood-pressure-lowering effect. The DASH investigators responded clearly and definitively: no dice. The benefits were due to the diet as a whole.
The danger of this sort of deceptive advertising is simple: Hypertension is dangerous—sometimes fatal. Consumers who are led to believe that milk will reduce their blood pressure may neglect more effective diet changes or medications they may need. PCRM filed a previous complaint with the Federal Trade Commission about inappropriate claims in the "Milk Mustache" ads. Both complaints are currently under investigation.