Does a low-fat diet protect against heart disease? Will taking calcium supplements help reduce the risk for osteoporosis? Can staying hydrated while running a marathon actually be dangerous?
These days, the rules change so quickly that it's tough to get a definite answer about how to optimize your health and improve your quality of life or your athletic performance.
Scientific research uses several different types of studies to reach a conclusion. It can be misleading if a single finding gets reported without the rest of the information.
Here are some suggestions to help you assess the latest nutrition news and decide if it's something you need to take to heart.
Does the study pertain to me?
To evaluate a nutrition story, first ask yourself what the study's findings mean for you personally. Do I fit within the category of people the study is investigating?
For example, if the study involved men older than 50 and you're a 30-year-old woman, it may not have much relevance to you.
What kind of study is it?
You're apt to read about several types of human studies in the media including case-controlled studies, which look at characteristics of one group of people who already have a certain condition and compare them with a similar group of people who don't.
Cohort studies, on the other hand, simply follow a large group of people over a long time and track something about them, such as their diet, before anyone develops the disease being studied. Researchers don't intervene to see how a specific behavior affects a health outcome. Cohort studies are useful for establishing relationships, such as the link between dairy product consumption and osteoporosis.
Another type of study is a double-blind, randomized controlled trial. It follows a group of people over time to see how a specific behavior or treatment affects a health outcome. The people in the study are randomly assigned to receive or not receive the medication or treatment. To avoid bias, researchers don't know who's receiving which intervention.
Overall, double-blind, randomized controlled trials and cohort studies are considered superior to case-controlled studies because they tend to provide more reliable results than single, smaller studies that ask people about their past activities.
Sometimes, multiple, small studies can be as valid as one large, double-blind randomized study. Evaluation of the results of multiple small studies is called a meta-analysis.
You'll also want to determine who conducted the study and where it was published. The most reliable studies come from well-known, peer-reviewed journals, such as the Journal of the American Dietetic Association. Studies published in minor journals are often not as reliable. Also consider who sponsored the study. The sponsor should not have any ties to the outcome of the study. For example, a study on the health benefits of chocolate would be suspect if sponsored by a candy maker.
Get the big picture
Once you've determined a study is relevant to you and credible, talk with your doctor about the report. Also, a registered dietitian can recommend nutritional changes that may reduce your risk for disease.