Did chicken beat red meat for your heart?

No. In this study poultry, such as chicken, came with slightly more heart disease or stroke, and so did red meat. Each 2 servings more of poultry a week came with a 4% higher risk of heart disease or stroke. Each 2 servings more of unprocessed red meat a week came with a 3% higher risk. Their likely ranges are the same, 1% to 6% higher, so the gap between the two could be chance. Processed meat, such as bacon and sausage, came with the most, a 7% higher risk at 2 servings a week than at none. For fish the figure was 0%, so no clear link (Zhong, 2020). Red meat also came with a 3% higher risk of dying, and poultry had no clear link with dying (Zhong, 2020). The authors say the poultry result may be related to fried chicken (Zhong, 2020). This was in 29,682 US adults, half of them followed for 19 years or more (Zhong, 2020). The study can't show the meats caused the heart disease or strokes. The table below puts all four foods in the order of the study's estimates. Every number links to its source.

The short version

• Processed meat came with the most extra heart disease or stroke, a 7% higher risk at 2 servings a week than at none (Zhong, 2020). In 100 people across 30 years, that is about 2 more cases of heart disease or stroke. 2 servings are 4 slices of bacon. In two groups of the same size, it is about 13 cases for every 12 among people who ate none.
• Chicken didn't come with less heart disease than red meat. Poultry came with a 4% higher risk of heart disease or stroke for each 2 servings more a week, and unprocessed red meat with a 3% higher risk (Zhong, 2020). The gap between the two could be chance.
• Fish came with no clear change in the risk of heart disease or stroke (Zhong, 2020).
• The authors call every one of these rises small. This study watched what people already did, so it can't show the meats caused the heart disease or strokes (Zhong, 2020).

The four foods, in the order of the study's estimates

The order is by the study's estimate of how much the risk of heart disease or stroke rose. It is not a proven ranking. For heart disease or stroke, the study compared 2 servings of processed meat a week with none. For the other three foods it compared any 2 servings more a week, such as 3 servings against 1. For the risk of dying, every row is for 2 servings more a week (Zhong, 2020). The likely range is in brackets. The middle column puts the same risk as more cases of heart disease or stroke in 100 people across 30 years.

The study didn't test the four foods against each other. Poultry and red meat have the same likely range for heart disease or stroke, so which of the two comes higher could be chance. The percentages compare risks between groups. They aren't what any one person would gain or lose by changing what they eat.

A serving was 2 slices of bacon, 2 small sausages or 1 hot dog for processed meat. It was 4 ounces (about 113 g) of unprocessed red meat or poultry, or 3 ounces (about 85 g) of fish (Zhong, 2020).

Behind the poultry and fish results

• The authors say the poultry link may be related to fried chicken, which was counted as poultry. The studies didn't all record how food was cooked, so fried chicken couldn't be separated out (Zhong, 2020).
• Poultry was linked to more heart disease or stroke and yet had no clear link with the risk of dying. The authors say the reasons need more study (Zhong, 2020).
• With a different statistical model, the red meat link with heart disease or stroke was no longer clear (Zhong, 2020).
• Whether the fish was fried couldn't be told apart either. Other pooled studies have mostly linked fish to slightly less heart disease, and the authors say fish remains uncertain (Zhong, 2020).

The study of 29,682 people

Zhong and colleagues pooled the records of 6 long-running US health studies. People were 53.7 years old on average, and none had heart disease or a stroke behind them at the start. The study used one report of what each person usually ate, taken between 1985 and 2002. Half were followed for 19 years or more, some for up to 30. In that time 6,963 got heart disease or had a stroke, and 8,875 died (Zhong, 2020). Heart disease or stroke here means coronary heart disease, heart failure, a stroke, or dying of heart and blood vessel disease (Zhong, 2020).

• The study gives no figure for eating more than 2 servings of processed meat a week. Its authors say people who eat more servings a week would have greater risks (Zhong, 2020).
• The typical person ate 1.5 servings of processed meat a week, 3 of unprocessed red meat, 2 of poultry and 1.6 of fish (Zhong, 2020).
• In a first look by age, the processed meat estimate was highest in adults under 45, at 17% higher. It was 12% higher at ages 45 to 64. At 65 and over there was no clear link, with an estimate of 0% and a likely range from 5% lower to 5% higher. The authors call these age results exploratory (Zhong, 2020).
• The results are adjusted for age, sex, education, smoking, alcohol, exercise, total calories and the rest of the diet (Zhong, 2020).

How far to trust these numbers

• This study watched what people already did. The authors say it could not establish that the meats caused the heart disease, strokes or deaths (Zhong, 2020).
• The study used one report of what people ate, and their diets may have changed over the years. The authors say errors in what people report eating were unavoidable (Zhong, 2020).
• People who ate the most meat and fish also smoked more often and had a higher body mass index. The study adjusted for smoking and other habits, but not for body mass index, and the authors say other differences were still likely (Zhong, 2020).
• The rises are small. The authors put the estimates at about 3% to 7% in relative terms, and under 2 more cases in 100 people across 30 years (Zhong, 2020).
• Everyone lived in the US, so the results may not apply in other countries (Zhong, 2020).

Sources

• Zhong VW et al. Associations of processed meat, unprocessed red meat, poultry, or fish intake with incident cardiovascular disease and all-cause mortality. JAMA Intern Med, 2020.