Sometimes in life, we don't see the forest for the trees. And the field of nutrition is no exception. We can get so focused on the health benefits of a certain vitamin or phytochemical that we miss an important point: Different components in a single food can work together to benefit our health, and so can components in different foods that are eaten together.
I remember sitting in Nutrition 101 class 20 years ago and learning that vitamin C (from citrus fruits and dark-green vegetables) enhances the body's absorption of iron (found in lean meats, fish, beans, and some leafy green veggies) when these foods are eaten at the same time. This was an early example of what we call "food synergy."
David Jacobs, PhD, a researcher from the University of Minnesota, loosely defines food synergy as the idea that food influences our health in complex and highly interactive ways. The Produce for Better Health Foundation explains it as nutrients working together to create greater health effects.
Either way, food synergy is a very good thing. It brings us back to the basics: For good health, it's important to eat a variety of whole foods.
There is still much we don't know about how the components in food work together. Case in point: In the past 10 years, scientists have identified hundreds of biologically active plant-food components called phytochemicals (also called phytonutrients). A decade ago, we didn't even know about phytochemicals like lycopene (the one that has made tomatoes famous) or anthocyanins and pterostilbene (which have propelled blueberries into the news).
We do know that eating food as close to its natural form as possible is by far our best bet for improving health and preventing disease. Vegetables, fruit, whole grains, nuts, and legumes are great examples of foods that are rich in a combination of important vitamins, minerals, fiber, protein, antioxidants, and more.
Here are just a handful of examples in which different nutrients and components in food work together:
- Pairing broccoli with tomatoes could be a match not only made in Italy, but in health heaven. In a study to be published in the December 2004 issue of the Journal of Nutrition, prostate tumors grew much less in rats that were fed tomatoes and broccoli than in rats who ate diets containing broccoli alone or tomatoes alone, or diets that contained cancer-fighting substances that had been isolated from tomatoes or broccoli. The take-home message: A lycopene supplement may not hurt, but the whole tomato will probably help more. And a tomato eaten with broccoli may help a lot more.
- Antioxidants like vitamin C and vitamin E; isoflavones from soybeans; and other compounds are thought to be important in slowing the oxidation of cholesterol -- which is as important to reducing your risk of congestive heart disease as lowering your blood cholesterol levels. Antioxidant protection is a complex system that includes many nutrients and phytonutrients. You need all of them for maximum effect.
- Research on the so-called DASH diet (for Dietary Approaches to Stop Hypertension) showed how different dietary patterns build on each other. A diet high in fruits and vegetables lowered blood pressure. But blood pressure went down even more when people also ate a reduced-fat diet and included daily servings of low-fat dairy products. Blood pressure was lowered the most when people did all this plus ate less sodium.
"Eating a little "good fat" along with your vegetables helps your body absorb their protective phytochemicals."
- Three B vitamins (folic acid, vitamin B-6, and B-12) TOGETHER reduce the level of an amino acid that, in high levels, is thought to damage artery linings, leading to heart attacks and strokes.
- Test-tube studies have shown that vitamin C and the phytoestrogen found in various fruits and vegetables, whole grains, and beans (including soy) work together to inhibit the oxidation of LDL "bad" cholesterol.
- A recent study found that the phytochemicals quercetin (found mainly in apples, onions and berries) and catechin (found mainly in apples, green tea, purple grapes, and grape juice) worked together to help stop platelet clumping. Platelets are a component in blood that play an important role in forming clots. Platelets' clumping together is one of several steps in blood clotting that can lead to a heart attack.
- The Mediterranean-style diet is a perfect example of food synergy because it includes several healthful food patterns. (It's rich in plant foods, whole grains, legumes and fish; low in meat and dairy products; and contains more monounsaturated than saturated fats because of its emphasis on olives, olive oil, and walnuts.) A recent study concluded that the Mediterranean diet may reduce the prevalence of both metabolic syndrome (a condition that includes excess body fat, high blood fats, and high blood pressure) and the cardiovascular risk that goes along with it. Another study found that a Mediterranean diet was associated with a 23% lower risk of early death from all causes.
- Several dietary factors -- including saturated fat and, to a lesser extent, cholesterol -- work to raise cholesterol in the human body. Several others, like plant sterols, soy protein, soluble fiber, and foods such as oats and nuts, help lower blood cholesterol levels. Your cholesterol levels are determined less by the intake of one particular nutrient than by your overall diet.
- Eating a little "good fat" along with your vegetables helps your body absorb their protective phytochemicals, like lycopene from tomatoes and lutein from dark-green vegetables. A recent study measured how well phytochemicals were absorbed after people ate a lettuce, carrot, and spinach salad with or without 2 1/2 tablespoons of avocado. The avocado-eating group absorbed 8.3 times more alpha-carotene and 13.6 times more beta-carotene (both of which help protect against cancer and heart disease), and 4.3 times more lutein (which helps with eye health) than those who did not eat avocados.
- In lab studies, Cornell University researchers found that apple extract given together with apple skin worked better to prevent the oxidation of free-radicals (unstable molecules that damage cells and are believed to contribute to many diseases) than apple extract without the skin. They also found that catechins (a type of phytochemical found in apples), when combined with two other phytochemicals, had an effect that was five times greater than expected.
- Studies have indicated that oats may help protect against heart disease. Besides being one of our best sources of soluble fiber, oats contain a laundry list of other healthful compounds, including beta-glucan; a beneficial amino acid ratio; magnesium; folic acid; tocotrienols; and a phytochemical so far identified only in oats -- avenanthramides. The protective effect of oats is thought to come from the collective effects of all of these components.
All these examples remind us of just how complex nutritional relationships are. In my opinion, Mother Nature knew what she was doing when she created plant foods: There is magic in the packaging.