As head of the renowned Alzheimer’s Prevention Clinic at Weill Cornell Medicine and NewYork-Presbyterian, Richard S. Isaacson, MD, is on top of the latest research on Alzheimer’s disease. Groundbreaking studies show that proper diet can make a real difference not only in slowing the progression of the disease but also in preventing it.
Here, Dr. Isaacson explains how we can change our eating habits to fight Alzheimer’s. His recommendations are not specifically designed for weight loss, but most overweight people who follow this eating plan will lose weight—important because obesity more than triples the risk for Alzheimer’s.
The Okinawa Centenarian Study (an ongoing study of centenarians in the Japanese prefecture of Okinawa) found that these long-lived people typically consume fewer calories (up to 1,900 calories a day) than the average American (up to 2,600 calories).
Lowering calorie intake appears to reduce beta-amyloid, particles of protein that form brain plaques—the hallmark of Alzheimer’s disease. A 2012 study at the Mayo Clinic found that people who overate had twice the risk for memory loss…and those who consumed more than 2,142 calories a day were more likely to have cognitive impairment.
I generally advise my patients to try to have fewer than 2,100 calories a day. I can’t give an exact number because calorie requirements depend on body type, activity level, etc. Many of my patients tend to consume less than 1,800 calories a day, which may be even more protective.
Bonus: Calorie restriction also lowers insulin, body fat, inflammation and blood pressure, all of which can reduce the risk for cognitive impairment. It even improves neurogenesis, the formation of new brain cells.
Less Carbs, More Ketones
Glucose from the breakdown of carbohydrates is the fuel that keeps the body running. But you don’t need a lot of carbs. Ketones, another source of fuel, are healthier for the brain.
When you restrict carbohydrates, the body manufactures ketones from stored fat. On occasion, a “ketogenic diet” is recommended for some patients with Alzheimer’s disease because ketones produce fewer wastes and put less stress on damaged brain cells. There’s some evidence that this diet improves mild cognitive impairment symptoms (and theoretically may slow further damage).
We previously found in our clinic that patients consumed an average of 278 grams of carbohydrates daily before their first visits. We recommend reducing that slowly over the nine weeks of the diet plan to 100 to 120 grams of carbohydrates daily. (One sweet potato has about 23 grams.) The USDA SuperTracker website (SuperTracker.USDA.gov) gives carbohydrate amounts and other nutritional information for specific foods. Eat healthful carbohydrates such as beans and whole grains in moderation. Unlike refined carbs, they are high in fiber and can help to reduce insulin resistance and improve blood sugar control—which reduces risk for Alzheimer’s.
Some trendy diets recommend extreme fasts. With the Alzheimer’s prevention diet, you’ll fast—but mainly when you wouldn’t be eating anyway, during sleep!
Several times a week, you’ll go without food (particularly carbohydrates) for more than 12 hours. After 12 hours, the body starts making ketones. This type of fast, known as time-restricted eating, reduces inflammation, improves metabolic efficiency and improves insulin levels, insulin sensitivity and brain health.
How to do it: Eat an early supper—say, at about 5 pm. You won’t eat again until after 5 am the next day. Your eventual goal will be to fast for 12 to 14 hours five nights a week.
The Institute of Medicine recommends getting 10% to 35% of calories from protein—go for the higher end. On a 2,000-calorie diet, that’s about 175 grams. (Five ounces of cooked salmon has about 36 grams of protein.)
The amino acids in protein are important for memory and other brain functions. Protein-rich foods often are high in B vitamins, including folic acid and vitamins B-6 and B-12. The Bs are critical because they reduce homocysteine, an amino acid linked to poor brain performance and an increased Alzheimer’s risk.
Which protein: Chicken, fish, nuts, legumes and eggs all are good choices. I recommend limiting red meat to one weekly serving because of potential associated health risks, including an increased risk for certain cancers…and because too much saturated fat (see below) can be a problem.
Helpful: Aim for four to eight eggs a week. They’re high in selenium, lutein, zeaxanthin and other brain-healthy antioxidants.
Limit Saturated Fat
A large study found that people who eat a lot of foods high in saturated fat—rich desserts, red meat, fast food, etc.—may be up to 2.4 times more likely to develop Alzheimer’s disease.
Saturated fat limits the body’s ability to “clear” beta-amyloid deposits from the brain. It also raises cholesterol and increases the risk for cardiovascular diseases—and what’s bad for the heart also is bad for the brain.
Consuming some saturated fat is healthful—it’s only in excess that it causes problems. The American Heart Association advises limiting it to about 5% to 6% of total calories. I recommend a little more—up to 10% of your daily calories. On a 2,000-calorie diet, the upper limit would be about 20 grams. (One ounce of cheese can have as much as eight grams.)
Fish, Turmeric and Cocoa
Studies have shown that a few specific foods can fight Alzheimer’s…
Fish. A UCLA study found that adults who regularly ate foods high in omega-3 fatty acids (the healthful fats in fish) had a lower risk for mental decline. Other research has shown that low blood levels of DHA (a type of omega-3) are linked to smaller brain volume and lower scores on cognitive tests.
My advice: Eat one serving of fatty fish (such as wild salmon, mackerel and sardines) at least twice a week.
Turmeric. In India, where people use the spice turmeric frequently, the risk for Alzheimer’s is lower than in the US. This doesn’t prove that turmeric is responsible (genetic factors, for example, also could be involved), but other evidence suggests that it’s protective. Turmeric contains the compound curcumin, which has potent antioxidant and anti-inflammatory effects.
My advice: Use the spice in recipes—don’t depend on supplements—because curcumin is fat-soluble and absorption is enhanced by the fat in foods.
Cocoa. The flavanols in cocoa improve memory and other cognitive functions. They also have been linked to reduced blood pressure and improved insulin resistance.
My advice: Buy chocolate bars or cocoa powder that lists purified cocoa flavanols on the label.