When the government issues new guidelines about food and healthy eating, most Americans throw up their hands in dismay and walk away baffled by the suggestions. Many say the recommendations do not reflect their traditional, social, or cultural eating habits. For example, they may never drink milk. Even if the government recommends drinking more milk every day, it isn’t going to happen. Others complain that healthy eating messages are too complex and don’t fit into their busy lifestyle. They simply can’t give that much attention to what they eat each day. And, last, and probably most important, Americans are terribly confused because it appears that our message about healthy eating keeps changing.
Perhaps if the average American understood more about how these recommendations came about they would be less anti-science and more willing to hear, and possible use, healthy eating messages. Nutrition science is a dynamic process. It relies on scientific studies that often investigate a single nutrient, such as potassium.
So how do scientists get from studies on potassium to recommending what food you should eat? Most healthy eating recommendations come from a balance of scientific evidence and scientific judgment. This is often referred to as an evidence-based approach. Scientists gather all the research available to date. They look at the findings and use this evidence and their trained judgment to make recommendations. Evidence-based scientific reviews are considered systemic, comprehensive, and minimize bias.
What did the research tell scientists about potassium? Too little potassium contributes to high blood pressure. Get more potassium and blood pressure goes down. And, survey research shows that a large percentage of Americans do not get enough potassium. The next, and sometimes the hardest step is to take these scientific findings and translate them into food choices that become part of meals people usually eat.
Fruits and vegetables are excellent sources of potassium. Encouraging people to eat more fruits and vegetables is a simple way to provide an adequate potassium intake and reduce the overall risk for high blood pressure in the US. Suggesting that we eat fruits and vegetables rather than taking a potassium supplement is also important. Most healthy eating messages focus on foods not supplements.
Fruits and vegetables offer us many important nutrients beside potassium, like vitamin C and folic acid which would not be found in a potassium supplement. In addition to vitamins and minerals, fruits and vegetables contain other valuable components, like disease-protecting flavonoids. When we depend on supplements, instead of food, we shortchange ourselves of nutrients and other health-giving substances.
What makes this confusing for you is that the evidence scientists examine continues to change. If the research analysis was done in 1995 the evidence may lead to one conclusion. Do the same analysis again, in 2011, after more research has been done, and the findings and recommendations may be different. It’s not that scientists have changed their story, but they have different evidence upon which to build their recommendations. You may not appreciate that science is always moving forward. All you think is that the scientists have changed their minds and they are telling you something different again.
A good example of this flux of information is the recommendations on eating fat. In the mid-80’s we were all told to lower our total fat intake. Today, we are told to moderate our fat intake and be more selective about the types of fat we eat. The reason, the scientific evidence evolved. Scientists realized that some fats, saturated in particular, were less healthy and other fats, like monounsaturated (olive oil, canola oil) were health promoting. Today, the focus is removing trans fat (hydrogenated vegetable oils) from foods. Science evolves, it does not contradict itself. When the first recommendations about lowering overall fat intake were made, all of the evidence we have today was not available to analyze.
So, the next time you hear new and possibly contradictory nutrition advice, don’t think the scientists can’t get it right and they are always changing their minds. Think instead — wow — all that scientific research must be turning up a lot of interesting and important findings. Cut the scientists a break, they are working hard to help us eat healthy and give us the best advice possible based on the evidence they have.
Bottom line: Your mother was right – eat your fruits and vegetables because they are good for you – even the scientists agree with this and that message never changes.
