Ask Dr. H: Lean chicken and cholesterol

Question:

I buy boneless, skinless chicken breasts because they're much lower in fat than pork or beef. But I was shocked to learn they're high in cholesterol. How can Perdue and Tyson make claims that lean chicken is good for you?

Answer: It's not the cholesterol in food that you should be overly concerned about; rather, it's the amount of heart-clogging saturated and trans fat that will raise your blood cholesterol and get you in trouble.

While boneless, skinless chicken breast is low in fat, it does contain a fairly high amount of cholesterol - approximately 65mg per 4-ounce serving. It's recommended to limit one's total daily cholesterol intake to 300mg or less to be heart-healthy.

But to the surprise of many, eating cholesterol-rich, low-fat foods like eggs or boneless skinless chicken breast has only a small role in raising one's LDL "bad" blood cholesterol level. In a study of more than 80,000 female nurses, Harvard researchers actually found that increasing cholesterol intake by 200mg for every 1,000 calories in the diet (about an egg a day) did not appreciably increase the risk for heart disease.

In one study, for every additional 100mg of cholesterol consumed up to a total intake of 500mg per day, there was a 2 percent to 3 percent increase in the blood cholesterol level. Further increases in cholesterol intake beyond 500mg per day seemed to have little additional effect on raising the blood cholesterol level.

In a second study involving folks who had normal baseline cholesterol, a low-fat diet with high cholesterol intake (600mg/day) from eating shrimp raised LDL "bad" cholesterol by 7 percent, but also raised their HDL "good" cholesterol levels by 12 percent and decreased their triglycerides by 13 percent.

In that same second study, folks who consumed a low-fat, high-egg diet (cholesterol intake 600mg/day) raised their LDL "bad" cholesterol by 10 percent and their HDL "good" cholesterol by 8 percent.

Most folks who have a high-cholesterol diet also have a high-fat diet, but in folks who consume greater than 500mg per day of dietary cholesterol, a reduction in intake to 250mg per day can reduce the total blood cholesterol by 5 percent to 7 percent, which may be predicted to translate into a 10 percent reduction in the risk of coronary heart disease.

Q:

I just read about a study showing that getting a flu shot can reduce the risk of having a heart attack. Do you have any idea why that might be so?

A: The study you're citing comes from a just-published paper in the Canadian Medical Association Journal. It was a retrospective British study in which researchers looked at data from 78,706 patients ages 40 and older. Those who had received a flu shot between September and mid-November had a 21 percent heart attack reduction risk; those who received their vaccine after mid-November had a 12 percent reduced risk of heart attack.

Interestingly enough, those who received a pneumonia vaccine did not have a reduced risk of heart attack.

While the study does show an association, it does not prove a link between flu vaccines and a reduced risk of heart attack.

The researchers are not sure how to explain their findings, but a plausible explanation might be that those receiving flu shots are simply more proactive in their overall medical care, including better attention to cholesterol and blood pressure.

If it were due to fever, dehydration, and infection, I would think the pneumonia shot would have had some effect on heart attack risk reduction, but it did not. That said, even if there is no proven link and it's merely findings by chance, it's still a good idea to get a yearly flu vaccine to avoid getting sick from the flu.