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There is a growing body of scientific evidence that indicates our food choices can prevent disease and increase our lifespan. Leading causes of death like heart disease, cancer, and diabetes are greatly impacted by diet and lifestyle. Even Alzheimer’s disease is influenced by our food choices.

The World Health Organization states, “Nearly half of all cancers can be prevented.”1 The American Heart Association advises, “A healthy diet and lifestyle are your best weapons to fight cardiovascular disease.”2 According to the Centers for Disease Control and Prevention, diabetes and weight can be controlled through regular exercise and eating a healthy diet.3 A recent National Institute of Health consensus panel reported, “Many studies indicate that healthy lifestyle habits—including diet, physical activity and cognitive engagement—are providing insights into the prevention of cognitive decline and Alzheimer’s disease.”4

If diet is so important what should we eat? The major components of our food are carbohydrates, protein, and fat. This is common knowledge but diets or food plans seldom look at what role each plays in promoting health. The United States Department of Agriculture has designed the Food Plate to give us guidelines for what we should eat and in what proportion. However, the recommendations have been influenced by politics and seem to disregard some of the current scientific research. In light of the importance of food choices in preventing disease, how each food group, carbohydrates, protein and fat, builds and restores our body deserves a second look.

Carbohydrates are a major source of fuel, nutrients and fiber. When carbohydrates are digested they become primarily glucose, a simple sugar that is the major energy source for the body. Carbohydrates are classified as simple and complex. Simple carbs are digested and enter the blood stream quickly and provide an immediate source of energy. Examples of simple carbs include bread, pasta, cookies, cakes, candy, sodas, fruit juices and many packaged breakfast cereals. Whole foods like grapefruit, kiwi, pears, oranges, watermelons, potatoes and milk are also simple carbs but contain more nutrients and fiber than the processed foods listed above and take longer to digest.

Complex carbs contain less sugar and more fiber, protein and fat, so they take longer to digest. Because they enter the bloodstream more slowly, they are a more constant and even source of energy. Examples include whole grains, vegetables such as broccoli and cauliflower, leafy greens such as spinach, kale, and chard, some fruits such as apples, plums, cherries, avocados, asparagus, beans and peas.

The United States Department of Agriculture’s Food Plate5 recommends the majority of our diet be carbohydrates although the latest scientific evidence points to excessive carbohydrates, particularly simple carbs, as a major source of obesity and diabetes. It is not just the calories that are problematic, it is how they are digested and stored. An excessive amount of glucose in the blood affects insulin production and insulin production affects how fat is utilized and stored. Insulin dysregulation is a major contributor to diabetes.

Proteins are the building blocks of the body. The basic structure of our cells is protein. The body’s bones and organs are made of protein. So are the outer layers of skin, the hair and the nails. Red blood cells contain hemoglobin, a protein compound that carries oxygen throughout the body. Blood plasma is made of lipoproteins and transports fat and proteins. Enzymes made of proteins have specific tasks, such as digesting food and making new cells. The brains neurotransmitters are built of protein. Without protein we would literally fall apart.

When proteins are digested they become amino acids. Because essential amino acids are so critical for a healthy body, it is important to consume healthy proteins. Meat, poultry, fish, dairy, and eggs are complete proteins containing all the amino acids. Incomplete proteins must be combined to insure all amino acids are present. The pairing of rice and beans is an example. The best source of plant protein comes from legumes, such a lentils, beans, peas, tofu and nuts and seeds.

Good fats are essential for health. The brain, which is 60 percent fat, needs fat to build cells and to facilitate communication between cells. Fat is also the main fuel for our muscles, including the heart. It’s necessary for healthy liver and gall bladder functioning and for the absorption of fat-soluble vitamins. It is required for the digestion of proteins. Stored fat enhances the function of the immune system and helps fight infection. Fat cells produce hormones and other compounds that affect metabolism, weight and overall health.

Sources of healthy fat include olive oil, coconut and palm oil, flax seed oil, whole milk and eggs, butter and lard, avocados, walnuts, almonds and other nut butters, sunflower and other seeds and seed butters, fish and fish oil, and fat from farm raised beef, pork, chicken, duck and turkey.

The Food Plate suggests that fat be 10 percent of the diet, and recommends limiting butter, milk fat, animal and poultry fat, coconut and palm oil. Their concern is that fat, particularly saturated fat causes heart disease. Dr. George, V. Mann, former director of the Framingham Heart Study says that this idea, disputed by numerous studies, “Is the greatest biomedical error of the Twentieth Century (Leas, p. 15).”6 Many nutritionists recommend that fat make up at least 30 percent of total calories consumed.

A healthy diet is one that includes whole foods, naturally grown or raised, in a balanced proportion of roughly 40 percent carbohydrates, 30 percent protein and 30 percent fat.7 The emphasis should be on complex rather than simple carbohydrates, a variety of proteins, and healthy fats. Bodies digest and processes food differently, so each person needs to find the right balance for their body.

Although the axiom “calories in, calories out” has fallen from favor, it included calories from processed foods, and soft drinks and sugary juices that may affect appetite, metabolism, and fat storage. Eliminating or limiting those foods may make that equation viable again. Eating consciously, and choosing food with your long-term health in mind has the potential to prevent disease and extend your lifespan.


  1. The World Health Organization. (13 January 2015). Most types of cancer not due to “bad luck” IARC responds to scientific article.
  2. The American Heart Association’s Diet and Lifestyle Recommendations.
  3. How do you prevent diabetes?
  4. Daviglus, M.L., Bell, C.C. Berrettini, W. et al. (2010). NIH State-of-the-Science Conference Statement on Preventing Alzheimer’s Disease and Cognitive Decline. NIH Consensus Stat-of-the-Science Statements 27:1-30.
  5. Food Plate. USDA, 2014.
  6. Leas, C. (2008). Fat: It’s Not What You Think. Amherst, NY: Prometheus Press.
  7. Beth Oliver, Fitness, Nike SPARQ Training Network

Karen V. Unger

Karen V. Unger is the author of the new book “Brain Health for Life, Beyond Pills Politics and Popular Diets.” Dr. Unger has a Master’s Degree in Social Work from Arizona State University, a Master’s Degree in Psychology from Chapman College and a Doctorate in Education from Boston University. She has written a previous book, book chapters, peer-reviewed articles, federal policy papers and an evidence-based practice kit for the Substance Abuse and Mental Health Services Administration of the U.S. Department of Health and Human Services. At Boston University she was a senior staff person at the Center for Psychiatric Rehabilitation and an adjunct professor at Sargent College of Allied Health Professions. She has also been a research associate professor at the Community Rehabilitation Division, Arizona State University in Tucson and is currently a research associate professor at the Graduate School of Education at Portland State University. Dr. Unger is president of Rehabilitation Through Education.