Can Eating Sugar Cause Dementia? A Plain-English Explanation
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Eating sugary foods could give you dementia. This is bad news if you're a sweet tooth. The good news is that changing what you eat can improve your brain health.

Recently, research has been looking at how blood sugar affects brain health and shows that people with high blood sugar levels have higher rates of Alzheimer’s disease. Age and genetics are risk factors for dementia that you have no control over. You can change your diet to increase energy in the short-term, and brain health in the long-term.

Why is Alzheimer’s Called Type 3 Diabetes?

Both type 1 and type 2 diabetes results in high blood sugar levels. Studies have shown that, compared to the general population, aging people with diabetes have:

  • Poorer memory
  • Slower recall
  • Higher levels of cognitive decline
  • Double levels of Alzheimer's

Alzheimer’s disease has been referred to as type 3 diabetes. There is a faster rate of cognitive decline in people with chronic high blood sugar levels. Up to 80% of people with Alzheimer’s disease have insulin resistance.

5 Ways High Blood Sugar Can Damage the Brain

1. Sugar creates a dangerous cycle of insulin resistance.

Poor insulin control appears to be a risk factor for Alzheimer’s disease. When you eat food, carbohydrates, starches and sugar in your food are broken down into another type of sugar called glucose. As your body digests the food, the stomach and small intestine absorb the sugar and send it into your bloodstream.

The hormone insulin pulls sugar from the bloodstream and gives it to cells in the organs and muscles. This gives your cells energy.

If your blood sugar levels are too high your body releases more insulin. So, insulin is trying to give MORE sugar to cells. Your cells will try to protect themselves from the powerful effect of insulin by becoming insulin resistant.

The pancreas is the large gland that creates the hormone insulin. It responds to this resistance by releasing more insulin, which starts a dangerous cycle.

Eating sugary and high-carbohydrate foods causes high blood sugar. The body tries to control this onslaught of sugar by pumping out a lot of insulin quickly. This is an "insulin spike."

Over time, high insulin causes cells to become resistant to insulin. Insulin resistance leads to higher blood sugar levels. High blood sugar levels cause more insulin to be released. Another dangerous pattern emerges.

2. Sugar drowns the brain.

Your brain requires a constant source of energy in the form of glucose (this is sugar once it's digested in your body). In the brain, glucose can easily enter the brain cells.

Unlike other cells in the body, brain cells do not need insulin to absorb sugar. They will absorb sugar directly from the bloodstream because sugar crosses the blood-brain barrier easily. However, now that there is sugar flowing through the brain, it doesn't produce mental energy. Only with insulin can the brain convert sugar into energy.

If years of eating sugars and simple carbohydrates have resulted in insulin resistance, then the brain has high levels of both insulin and sugar. The high load of insulin is trying to prevent the brain from using sugar and converting it into energy. The brain is almost swimming in sugar but can't use the sugar and can't convert it to energy to regulate body functions and help us think.

If the brain cells can't get the energy they need (from sugar), then they die. The sad irony is that, with insulin resistance, the brain cells are surrounded by sugar and are almost drowning in it but they just can't use the sugar.

3. High blood sugar causes inflammation.

High blood sugar also causes inflammation in your body. Inflammation has been linked with

  • Heart disease
  • Diabetes
  • Cancer
  • Alzheimer’s disease

Eating a diet high in sugar and simple carbohydrates leads to inflammation. This often happens as excess fat is stored around the abdomen. Abdominal fat releases cytokines, a type of protein that causes inflammation.

Inflammation on the inside of the body is similar to an infected cut on your skin: it is red, swollen and filled with puss. Inflammation in internal organs, such as the heart or brain, puts the body in a constant state of "fighting infection." This causes your cognition to break down, as the brain and the blood vessels running through it are swollen and irritated. Eating an anti-inflammatory diet can help reduce your risk of dementia.

4. Sugar clogs the brain.

The large amount of abdominal fat in obese people double's a person's risk of Alzheimer's. This is because obese people have "clumps" in their brains that literally clog thinking.

How? Amyloid proteins are toxic to the brain. Obesity leads to higher levels of amyloid proteins. When there are a lot of amyloid proteins, they stick together and form clumps. These clumps are found in the brains of people with Alzheimer’s disease.

5. High blood sugar can cause a stroke.

Insulin resistance affects the flow of blood to the brain. When brain cells don’t get enough blood, brain function suffers. A decrease in blood flow can lead to mini-strokes. High blood sugar levels can also make the blood vessels weak, like old leaky pipes. Strokes are one of the factors in developing dementia.

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5 Tips to Reduce Sugar in Your Diet

Sugar and sweeteners are added to many foods that we bake or buy in a box or can. When you stay aware of this fact it can be easier to lower your sugar intake. Eat a diet that is naturally low in sugar by following these steps:

  1. Don’t add sugar (or sweeteners!). When you are eating or drinking a beverage, stop and think before you add anything sweet. Try adding less sugar or syrup to your cereal, pancakes, coffee or tea.
  2. Don’t drink sugar. Drinks such as flavored coffee, hot chocolates, energy drinks and soda are famous for high sugar content. It is best to skip these altogether. If you must have one of these drinks, order the smallest possible size as well as a large glass of ice water or plain tea or coffee.
  3. Read the labels. When you are buying foods like dairy products, soups, sauces and jams, stop and read the label. If the first or second ingredient is sugar (or a form of sweetener) you will be getting an unplanned high sugar meal. Look for plain yogurt or soups and sauces with no added sugar.
  4. Make it tasty not sweet. Sweet is only one of the areas of taste. Explore different ways to add flavor without sugar. Have you tried adding a splash of vanilla to your morning coffee? Or other extracts like almond, orange, lemon or mint? You can also add spices like cinnamon, nutmeg, ginger or allspice to oatmeal or yogurt to enhance the flavor.
  5. Try fruit instead of sugar. When your taste buds do want something sweet, add a piece of fruit. Fresh, frozen or canned fruit can offer you a sweet treat. You also get the benefit of extra vitamins and nutrients that sugar can’t offer.

Low Sugar Dessert Ideas

There may be times when you make an exception to eat something sweet like a holiday or a birthday party. When you feel constantly deprived, you are more likely to binge on sweets when your self-control is tired.

Satisfy your sweet tooth while keeping your blood glucose levels stable by enjoying one of these sweet and tasty low sugar desserts:

  • Pear and cheese
  • Fresh berries with whipped cream (whip your own cream and try with no sugar or a small amount)
  • Baked apple sprinkled with cinnamon, nutmeg and walnuts
  • A small amount of dark chocolate with almonds
  • Homemade chia pudding (blend until smooth: ½ cup of milk or alternative milk with 2 tablespoons chia seeds, 1/8 tsp of vanilla, small amount of sweetener such as 1-2 soaked dates with your choice of flavor add-ins: such as peanut butter, chocolate, banana)
  • Strawberries dipped in chocolate
  • Unsweetened cream cheese on whole-grain crackers topped with sliced peaches
  • Simple frozen fruit “ice cream” (1/2 a cup of frozen berries or bananas blended until smooth and creamy)

Protect Your Brain, Protect Your Future

A high functioning brain is one of the keys to a high quality of life. Protecting your brain from damage is important. There any many factors that contribute to dementia. Some of the factors are in your control.

Insulin resistance is thought to cause a cascade of problems in your brain. Over half of the U.S. population is likely to be insulin resistant. The good news is that insulin resistance is both preventable and treatable. You can learn more about how you can protect your brain from the harmful effects of sugar. One way to protect your brain from too much sugar is to try this next recipe as a low-sugar way to satisfy your sweet tooth!

Paleo-style Blackberry and Nectarine Crisp

Desserts do not have to be unhealthy to be enjoyable! Consuming an excessive and unnecessary amount of sugar is not healthy for any part of the body, especially the brain. Even though we should protect our brains from high amounts of sugar, we all still need something sweet every now and then. Try this recipe for a low-sugar way to get a sweet treat!

Eating a serving of an oat-topped, low-glycemic blackberry and nectarine crisp is a delicious way to end a summer night’s dinner. A touch of maple syrup gives this dessert just enough sweetness.

Trading traditional white flour for pulverized oats increases the nutritional value of this dessert by adding fiber to the mix. Almonds add protein, and coconut oil adds healthy fat. If you’re not concerned about dairy, grass-fed butter is an acceptable substitution for the coconut oil.

Nectarines have plenty of vitamin A and fiber and do not require peeling as their skin is soft and melts into the crisp when cooked, keeping extra fiber intact. Blackberries contain a lot of antioxidants and anthocyanins, which are extremely anti-inflammatory.

Ingredients for the filling:

• ¼ cup + 1 tbsp (60ml) maple syrup

• 1 tablespoon lemon juice

• 2 tablespoon arrowroot or tapioca powder

• 2 tsp lemon zest

• 2 tsp lemon juice

• 1 tsp ground cinnamon

• ⅛ tsp salt

• 2 cups sliced nectarines (not necessary to peel)

• 2 cups blackberries

Ingredients for the topping:

• 1 cup rolled oats

• ¾ cup blanched almond flour

• ¼ teaspoon sea salt

• 2 tsp ground cinnamon

• ¼ cup refined coconut oil

• 3 tablespoons maple syrup


  1. Preheat the oven to 350 degrees.
  2. Combine the filling ingredients in a bowl and then transfer to an 8” x 8” pan.
  3. Make the topping by adding ¾ cup of the oats to a food processor and pulse until granular.
  4. Add the remaining oats, almond flour, salt, and cinnamon and pulse for 5 seconds.
  5. Pulse in the coconut oil and syrup just until the mixture has a few lumps in it.
  6. Drop quarter-size pieces onto filling and press down (if necessary).
  7. Bake the crisp about 38-42 minutes, or until the crisp is bubbly.

Nutrition Facts

Servings 12.0

Amount Per Serving

calories 184

% Daily Value *

Total Fat 9 g

14 %

Saturated Fat 4 g

22 %

Monounsaturated Fat 0 g

Polyunsaturated Fat 0 g

Trans Fat 0 g

Cholesterol 0 mg

0 %

Sodium 77 mg

3 %

Potassium 160 mg

5 %

Total Carbohydrate 25 g

8 %

Dietary Fiber 3 g

14 %

Sugars 12 g

Protein 3 g

6 %

Vitamin A

4 %

Vitamin C

19 %


23 %


3 %

* The Percent Daily Values are based on a 2,000 calorie diet, so your values may change depending on your calorie needs. The values here may not be 100% accurate because the recipes have not been professionally evaluated nor have they been evaluated by the U.S. FDA.


Diabetes Linked to Worse Cognition in Aging Patients

Avoiding Alzheimer’s Disease Could be Easier Than You Think

The Startling Link Between Sugar and Alzheimer’s

Alzheimer’s Association: Diabetes and Cognitive Decline

American Diabetes Association: Glycemic Index and Diabetes

Inflammation: An Unifying Theory of Disease?

American Heart Association: Tips for Cutting Down on Sugar

About the Author(s)

Crystal Jo is a Registered Nurse who is passionate about helping older adults live happy, healthy lives at home. As a freelance writer, she enjoys educating and inspiring seniors, and those who love them, to choose a healthy life.

Leslie Myers is a culinary professional with over thirty years of experience including healthy eating and cooking specialist, culinary instructor, restaurant owner and operator, caterer, operations manager, pastry chef, raw foods chef and culinary instructor. She is the owner of Foodsense, Now, a Solana Beach-based company which focuses on healthy eating for athletes. She is also the Professional Chef for Home Care Assistance, where she creates delicious recipes that promote brain health and healthy longevity and are appropriate for the changing dietary needs of seniors.

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