SOURCES: Russell de Souza, Sc.D., registered dietician, assistant professor, clinical epidemiology & biostatistics, McMaster University, Hamilton, Ontario, Canada; Lona Sandon, R.D., assistant professor, clinical nutrition, University of Texas Southwestern Medical Center at Dallas; Aug. 11, 2015, BMJ
TUESDAY, Aug. 11, 2015 (HealthDay News) -- A new review suggests that saturated fats, like those found in many dairy products and meat, may not be the big contributors to heart disease or early death that many think they are.
However, the Canadian researchers who did the review did find a clear link between heart troubles and trans fats, which are found in highly processed foods such as snacks, margarine and baked goods.
"Not all the studies we looked at reached the same conclusion, but generally what we found is that the association between a higher consumption of trans fats and a higher risk for heart disease and [early] death was very consistent," said study author Russell de Souza.
"And because we found no evidence that trans fat offers any health benefit, removing it from the foods we eat is the right idea," added de Souza, a registered dietician and an assistant professor of clinical epidemiology & biostatistics at McMaster University in Hamilton, Ontario.
"On the other hand, the association between consuming saturated fat and a higher risk for similar health issues was variable and unclear," he added. "But we want to be careful. We're not saying that we're confident that saturated fat is truly benign."
De Souza and his colleagues reported their findings in the Aug. 11 issue of the BMJ.
The study authors said that current dietary guidelines advocate limiting saturated fat consumption to less than 10 percent of total caloric intake, and limiting trans fats to less than 1 percent of one's diet.
The team's saturated fat analysis involved 41 studies conducted in the United States, the United Kingdom, Japan, Sweden, Finland, Denmark, Canada, China, Greece and Australia. A separate international investigation was also included in the review.
Their look at trans fat focused on 20 studies conducted in the United States, Finland, China and the Netherlands.
In the end, the team unearthed no clear evidence highlighting an association between higher quantities of saturated fat and a higher risk for dying from any cause.
Similarly, no link was found between saturated fat and a higher risk for stroke, type 2 diabetes, and/or heart disease.
That said, investigators cautioned that a lack of sufficient evidence meant that they could not rule out the possibility that saturated fat does contribute to a higher risk of dying early from heart disease.
On the other hand, the review did draw a strong link between the higher consumption of trans fat and a 34 percent bump in the risk of dying early from any cause, as well as a 28 percent bump in the risk of dying early specifically from heart disease.
And while no clear association was seen between trans fat consumption and a higher risk for either stroke or diabetes, trans fat was linked to a 21 percent bump in the risk for developing heart disease.
However, the study did not prove that consuming trans fats causes heart disease or early death.
Lona Sandon, an assistant professor of clinical nutrition with the University of Texas Southwestern Medical Center at Dallas, cautioned against interpreting the study's mixed message as a license to loosen up limits on saturated fat consumption.
"Trans fat remains a definite concern," she said. "Saturated fats are a little up in the air. Part of the problem is that we know that there are some saturated fats that are not harmful and possibly even beneficial. However, you cannot separate out the healthy types of saturated fats from those that are not so healthy. They come packaged together in foods," she explained.
So, Sandon said, "the message still remains to limit saturated fat and aim for getting your fats from the mono and polyunsaturated fats that we are pretty confident are good for health."
De Souza offered the same advice: "I would caution against ignoring strong and consistent evidence that we already have that shows that if we reduce saturated fat and replace it with healthful unsaturated fats, like olive oil and canola oil, we do see benefits in terms of reducing cholesterol levels and heart disease risk."
There's more on various types of fat at the U.S. Centers for Disease Control and Prevention.