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The Mad Cow Calculator -- Details

What is Mad Cow Disease?
"Mad Cow Disease" is the common name for a fatal disease of cattle. The disease is caused by an infection of the brain.

A similar disease occurs in humans. Strictly speaking, humans do not get mad cow disease, although it is often phrased that way. In humans, the condition should be called "new variant Creutzfeldt-Jakob disease."

How does the Mad Cow Calculator work?
  1. Your risk of having a fatal heart attack in the next 10 years is calculated using the so-called "Framingham equation." Although it has limits, it is the best tool available for predicting an individual's risk of heart attack. The equation may be found in:
    Anderson KM, Wilson PW, Odell PM, Kannel WB.
    An updated coronary risk profile. A statement for health professionals.
    Circulation. 1991; 83: 356-362. Pubmed record.
    The limits of the Framingham equation are discussed in a scientific statement issued by the American Heart Association and the American College of Cardiology:
    Assessment of cardiovascular risk by use of multiple-risk-factor assessment equations.
    Grundy SM, Pasternak R, Greenland P, Smith S, Fuster V.
    Circulation. 1999;100:1481-1492. Pubmed record
    Full text online
  2. Your cholesterol level is re-calculated. The cholesterol level you report to the Mad Cow Calculator is, to a small extent, determined by the beef you eat. We assume that the only beef you eat is in hamburger.

    We use the so-called "Hegsted equation" to estimate what your cholesterol level would be if you replaced the beef in your diet with a fat-free, cholesterol-free food having the same number of calories (broccoli, for example). The Hegsted equation may be found in:

    Keys A, Parlin RW.
    Serum cholesterol response to changes in dietary lipids.
    Am J Clin Nutr. 1966;19:175-181. Pubmed record.
    The Hegsted equation needs to know how many calories you eat daily. We assume your weight is steady. This means the calories you eat equals the calories you burn. To calculate the calories you burn, we first calculate the basal metabolic rate using the Harris-Benedict equation published in:
    Harris JA, Benedict FG.
    A Biometric Study of Basal Metabolism in Man.
    Washington D.C. Carnegie Institute of Washington (1919).
    Full text online. (Beware of secondary sources)
    A multiplier (1.4, 1.6, 1.8, or 2.0) adjusts the basal metabolic rate for the different activity levels.
  3. Using your "beef-free" cholesterol level from the Hegsted equation in step 2, your risk of fatal heart attack is re-calculated with the Framingham equation. The difference in risk between this risk and the risk from step 1 is your "beef-attributable" risk of fatal heart attack in the next 10 years. In other words, the difference represents the drop in your risk of heart attack if you switched from beef to broccoli in your diet.
  4. Your risk of Mad Cow Disease is calculated using a rather made-up equation. The ten cases of CJD became manifest over a 20 month span in 1994-1995 [1]. If we suppose a uniform incubation period of 10 years for CJD, then all 10 cases were infected during a 20 month period in 1984-1985, when the mean beef intake among the 56 million Britons was 181.5 g/person/week [2] (roughly equivalent to two hamburgers per week). Assuming the attack rate remains constant, an average Briton would have a 1 in 933,000 chance of developing CJD from 10 years of beef-eating. The risk per hamburger is roughly 2 in one billion.
Where can I read more about Mad Cow disease?
We suggest the following resources:

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