Every day we’re hit with headlines describing all sorts of miracle foods, supplements, etc. For example, a common headline might read “Blueberries are good for the brain” or “Beans reduce the risk of colon cancer by 20%.” The headlines always sound amazing yet simple – what better way to improve my health than to add a can of beans to my diet?
However, once you dig deeper, you’ll realize that many of these studies are much less relevant than what they seem when reading the headline.
Let’s take the hypothetical beans example from above. Beans are high in fiber, and yes, a high fiber diet may decrease the risk of certain cancers. But if you look at the overall numbers with respect to the contribution that beans make towards that reduction in cancer, risk reduction is almost meaningless.
First of all, the chance of any given person developing colon cancer in a given year is quite low. Second, there are many different factors that increase a person’s risk of developing colon cancer. Third, in a day and age when many people undergo screening tests for colon cancer (e.g. colonoscopy), the risk of developing cancer becomes even lower.
Let’s look at what the numbers really show
When you finally crunch the numbers, the benefit is practically nil. Although beans MAY reduce the risk of colon cancer by 20%, this is what’s called a relative risk reduction. Basically, when comparing people who don’t eat beans to those who eat the most beans, the latter will have a 20% lower risk of developing colon cancer. Sounds good, right? But what really matters is the absolute risk reduction. For example if 1 out of 200,000 people who don’t eat beans will develop colon cancer in the next year, then by eating a lot of beans, the risk goes down to 1 out of 250,000. Suddenly, this doesn’t seem like much. Although the numbers I used were hypothetical, they drive home the point.
Even worse is that sometimes the relative risk reduction will be meaningless. A recent study in JAMA Neurology showed a 6.5% worsening decline in cognitive function over 20 years between people who had untreated high blood pressure during middle age compared with their peers who had normal blood pressure. Yes, technically that’s a significant difference. However, 6.5% is nothing to get too excited about (however, it’s important to treat high blood pressure to prevent heart disease, strokes, kidney disease, etc.).
Another type of study you often come across is one that tests specific markers in the blood, and extrapolating benefits with respect to diseases based on these markers.
For example, let’s say a certain substance in the blood (we’ll call it substance A) is correlated to the development of heart disease. The researchers then give a group of volunteers a certain food or vitamin, and measure the concentrations of substance A in the blood. If they go down, then voila! The food that was studied is purported to fight heart disease. Again, life isn’t so simple. Often, things found in the blood may be markers of heart disease, but don’t necessarily cause heart disease. Reducing those markers does nothing to slash a person’s risk of suffering a heart attack. To show benefit, we need a study comparing heart attack rates in people who ate a certain food or took a certain medication or vitamin to those who didn’t.
What’s the bottom line?
If you enjoy beans or blueberries or any other healthy food, then by all means, indulge. And yes, you’re probably getting some health benefits. However, if you don’t enjoy those foods, then eat other healthy foods that you do enjoy. The small incremental risk reduction from any one food is minute.
If you want to reduce your risk of dying young and developing different diseases, then improve your lifestyle as a whole. Don’t smoke. Exercise every day and stay active. Follow a healthy diet rich in fresh fruits, vegetables, healthy fats, protein, and low in processed carbs and fats. Cut down on your stress. Focusing on the big picture will keep you on the road to good health much much more than beans or blueberries.