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Harvard Commentaries
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Reviewed by the Faculty of Harvard Medical School

Food for Thought Food for Thought

Back To The Stone Age

July 11, 2013

By Tara Mardigan, M.S., R.D., M.P.H.
Brigham and Women's Hospital

New research suggests we may be ignoring the most important organ of all when it comes to food and nutrition: that 3-pound thinker, the brain. Neuroscientists have recently modified their old belief that mental decline is an inevitable, unstoppable process of aging. It turns out that eating well may improve memory, mood, creativity, and help us to prevent or even reverse mental aging. Brain cells are more sensitive than other body cells to nutrients and chemicals, which determine at any given moment how the brain functions or malfunctions. To understand why, it helps to take a trip back in time.

Eating Defensively

Our brain craves the diet that helped form it in the first place. In the Stone Age humans foraged for wild plants, fruits, berries, roots, legumes, nuts and hunted for wild game and seafood. Humans didn't eat the refined grains that define today's colorless typical American diet. And, certainly, they didn't have cars to zip them to McDonald's drive-through windows so they could "supersize." The American diet is foreign to the brain. The mechanics of our brain are fine-tuned to a long-lost diet that existed in prehistoric days. Take a look at the difference:

  • Stone-Age Diet:
    • 65% fruits, vegetables, nuts, legumes, honey
    • 35% lean game, wild fowl, eggs, fish, shellfish
    • 3,000 calories per day with daily physical activity (largely from searching for food)
  • American Diet:
    • 55% "new" foods — cereal, grains, milk, milk products, sugar, sweeteners, separated fats, alcohol
    • 28% fatty meat, poultry, eggs, fish, shellfish
    • 17% fruits, vegetables, legumes, nuts
    • 2,000 to 2,500 calories per day with minimal physical activity

Feeding your Brain

Here are some tips from the Stone Age for fueling your brain for the short and long term:

  • Fruits and vegetables — Fruits and vegetables supply vitamins, minerals and antioxidants that help to protect against cellular damage that is a normal part of the aging process. Choose deeply hued produce such as blueberries and spinach. Aim for a variety of colors each day to get the full-spectrum of benefits of vitamins, minerals and antioxidants. Ideally, you should aim for two servings of fruits a day (medium fruit or half cup), and at least five servings of vegetables (half- to full-cup servings).
  • Friendly fats — The brain requires specialized fats to keep neurons' membranes flexible so that they can expand to receive messages. The solution is a balanced ratio of alpha-linolenic acid (ALA or "omega-3") and linoleic acid (LA or "omega-6"). Western diets tend to have an overload of omega-6 fats (from meat and dairy). You can correct the imbalance by eating more omega-3 rich sources such as fatty, cold-water fish (salmon, sardines, tuna, mackerel) or by adding flaxseeds or flaxseed oil.
  • Lean meats — Wild game is naturally low in fat (4.3%) compared with our major meat sources today (25% to 30%). Red meat is full of saturated fat, so be sure to limit it. For a modern-day wild-game equivalent, choose white-meat chicken or turkey and avoid the skin.
  • Nuts and legumes (dried beans) — Nuts and legumes are a perfect snack. They supply high-quality vegetable protein and healthy monounsaturated fats. They are an "original" food, or one that our ancestors' genes understood. A handful of unsalted nuts will go a long way between meals to fight that midday slump.
  • Grains — Processed, refined grain products simply didn't exist during the Stone Age. We can't seem to avoid them today. Many researchers fear that such grains have taken the place of fruits and vegetables in our diets today — another reason we may not be getting enough vitamins, minerals and antioxidants.
  • Limited dairy products — Back in the Stone Age, humans didn't keep domesticated animals, such as cows, so milk was nonexistent! To mimic a Stone-Age diet, you should limit milk, butter, cheese and other dairy products. In fact, many people today lack the enzyme lactase that is needed to digest milk products.
  • Sugar — What happened to the days when honey and fruit were used to satisfy a sweet tooth? Today, an average American consumes about 120 pounds of refined sugar a year. This unnatural overload drives up glucose, insulin, and triglycerides. This complex of abnormalities may increase stroke risk.
  • Potassium and sodium — Eat more potassium than sodium to help to regulate your blood pressure (assuming you have normal kidney function). Our ancestors got 7,000 milligrams of potassium each day (once again, through fruits and vegetables) and only 600 milligrams of sodium a day. Today we average only 2,500 milligrams of potassium and well over 4,000 milligrams of sodium. We’re paying a price with high blood pressure and its associated problems.

We do have some modern advantages to add to the mix, however:

  • Caffeinated liquids — Caffeinated beverages can increase alertness, concentration and decrease that tired feeling. Two cups of caffeinated beverages a day is a safe amount for most people. Avoid drinking caffeine all day long, and certainly stop within four hours of bedtime, as it can cause insomnia. Green tea contains some caffeine, but less than coffee, and it contains antioxidants. Brewing the tea for five minutes will release more of the antioxidants.
  • Vitamin supplements — Take a multivitamin and mineral supplement every day to help to maintain your minimum requirements. This will help to prevent vitamin deficiencies, such as B12 deficiency, that could lead to poor intellectual functioning.
  • Regular exercise — Use exercise as a mood booster. Be mindful: if you are choosing food to lift your mood, you have time to exercise. Even a 10-minute walk can release stress and decrease tension.

Tara Mardigan, M.S., R.D., M.P.H., is a nutritionist at Brigham and Women's Hospital. She earned a Bachelor of Science degree in nutrition from the University of New Hampshire. She completed her internship at Yale-New Haven Hospital in Connecticut and worked for three years as an inpatient dietitian at Massachusetts General Hospital before getting her master's degrees in nutrition and communication as well as public health at Tufts University.

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