FOOD: The Glycemic Index: Smart Brain Health After 60

When it comes to protecting your brain as you age, few things are as important as keeping your blood sugar stable. Surprising? It shouldn’t be. Our brains are highly sensitive to glucose swings—and the way we eat plays a huge role in how well our brains function day to day, and how they hold up over the years.

One of the most useful (and often underused) tools to support stable blood sugar is the glycemic index—especially for older adults.

So what is the glycemic index, and how can you use it to support long-term brain health without turning eating into a complicated math equation?

Let’s break it down.

What Is the Glycemic Index?

The glycemic index (GI) is a scale that ranks carbohydrate-containing foods based on how quickly and how much they raise your blood glucose after eating.

• Low-GI foods (55 or less): Digested slowly, cause a gradual rise in blood sugar

• Medium-GI foods (56–69): Moderate impact

• High-GI foods (70 or more): Quickly digested, cause a spike in blood sugar

Here are some examples:

Food	GI Score
White bread	75 (High)
Rolled oats	55 (Low)
Lentils	32 (Low)
Apple	36 (Low)
Cornflakes	81 (High)
Brown rice	68 (Medium)

These scores come from lab testing where a food’s blood sugar impact is measured against pure glucose. The lower the number, the more stable your blood sugar will be.

What Foods Don’t Have a GI?

This is something many people (and even professionals) get confused about.

The glycemic index only applies to foods that contain carbohydrates, because it's based on how quickly those carbohydrates are broken down into glucose and enter your bloodstream.

That means foods like salmon, eggs, cheese, olive oil, and meat don’t have a GI value at all—not because they’re missing from the list, but because they don’t significantly raise blood sugar in the first place.

These foods are what I call “blood sugar-neutral.” They’re not part of the glycemic index scale, but they’re incredibly useful because they can help slow down the absorption of carbs when eaten together in a meal.

To clarify:

Has a GI Score	Does Not Have a GI Score
Bread, rice, pasta	Salmon, chicken, tofu
Fruit and starchy veg	Leafy greens, mushrooms
Cereal, oats, legumes	Cheese, eggs, olive oil
Sugar, honey, fruit juice	Butter, vinegar, avocado

Understanding this distinction helps you build better-balanced meals—by pairing higher-GI carbs with foods that don’t raise blood sugar on their own, you can dramatically reduce the impact on your body.

Why the Glycemic Index Matters for Brain Health

Our brains rely on glucose for energy—but that doesn’t mean more is better. In fact, as we get older, the brain becomes less efficient at using glucose, especially if insulin resistance develops.

When blood sugar spikes sharply after high-GI meals, it can lead to:

• Brain fog

• Fatigue

• Mood swings

• Inflammation and oxidative stress

• Over time, damage to memory and executive function

Here’s what the research tells us:

• High-GI diets are linked with faster cognitive decline in older adults

• Blood sugar variability is associated with increased risk of dementia

• Insulin resistance in the brain may interfere with memory formation and the brain’s ability to clear amyloid-β and tau proteins (hallmarks of Alzheimer’s)

On the flip side, low-GI diets help preserve brain volume, protect memory, and support long-term cognitive resilience.

How to Use the GI in a Brain-Healthy Diet

You don’t need to become obsessive about numbers. Here’s a simple way to apply the glycemic index to your day-to-day meals:

1. Prioritize low-GI carbs

Choose whole, minimally processed carbs that digest slowly:

• Rolled oats, steel-cut oats

• Lentils, chickpeas, black beans

• Apples, pears, berries

• Sweet potatoes, barley, quinoa

• Whole rye or sourdough bread

2. Avoid eating high-GI carbs on their own

A slice of white bread or a banana by itself can cause a sharp rise in blood sugar—especially in older adults. But if you add some protein, fat, or fiber, that spike is blunted.

For example:

• A banana + a spoonful of peanut butter

• Toast + avocado

• Rice + chicken + vegetables

3. Think about the whole meal, not just one food

You don’t need to avoid higher-GI foods completely. Just build meals with a balance of carb, fat, protein, and fiber to support better blood sugar control.

A Brain-Smart Day on a Low-GI Plan

Here’s what a day might look like:

10:00 a.m.Steel-cut oats with chia seeds, walnuts, and blueberriesBlack coffee or herbal tea

2:00 p.m.Grilled salmon with lentil salad and roasted root vegetablesOlive oil and lemon dressing

5:30 p.m. light meal or snackPlain Greek yogurt with cinnamon and a few almondsorHummus with cucumber and cherry tomatoes

Gentle, satisfying, and steady all day.

Final Thoughts

The glycemic index isn’t a diet—it’s a tool. One that helps you make better choices for your brain, blood sugar, and long-term health. And the best part is, it’s flexible. You don’t have to count anything. Just think in terms of:

• Slower-burning carbs

• Combining foods wisely

• Reducing blood sugar swings throughout the day

That’s what keeps the brain sharp, the mood balanced, and the aging process a little more graceful.

And remember: not all healthy foods have a GI score—some simply don’t need one. That’s good news for your plate and your brain.

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EVIDENCE

Gilsing, A. M., Mayén, A.-L., van de Rest, O., & de Groot, L. C. P. G. M. (2020).Dietary glycemic index and cognitive function: A systematic review and meta-analysis. Nutritional Neuroscience, 23(5), 342–350. https://doi.org/10.1080/1028415X.2018.1513135

This meta-analysis reviewed findings from multiple studies and found that higher-GI diets were associated with poorer performance on memory and attention tasks, particularly in older adults.

Arnold, S. E., Arvanitakis, Z., Macauley-Rambach, S. L., Koenig, A. M., Wang, H. Y., Ahima, R. S., Craft, S., Gandy, S., Buettner, C., Stoeckel, L. E., Holtzman, D. M., & Nathan, D. M. (2018).Brain insulin resistance in type 2 diabetes and Alzheimer disease: Concepts and conundrums. Nature Reviews Neurology, 14(3), 168–181. https://www.nature.com/articles/nrneurol.2017.185

...This paper explores how insulin resistance in the brain may contribute to the development of Alzheimer’s disease, showing how impaired glucose metabolism can disrupt brain function.

Roberts, R. O., Cha, R. H., Mielke, M. M., Christianson, T. J., Pankratz, V. S., Boeve, B. F., Kremers, W. K., Geda, Y. E., Rocca, W. A., & Petersen, R. C. (2021).Association of dietary glycemic index and cognitive function: The Mayo Clinic Study of Aging. American Journal of Clinical Nutrition, 113(3), 587–593. https://doi.org/10.1093/ajcn/nqaa353

...This large cohort study found that older adults with higher dietary GI had worse cognitive scores, particularly in memory and executive function, supporting the role of diet in brain aging.

van de Rest, O., Berendsen, A. A. M., Haveman-Nies, A., & de Groot, L. C. P. G. M. (2015).The role of nutrition in brain aging and neurodegeneration: Implications for cognitive decline and Alzheimer’s disease. Nutrients, 7(10), 7920–7935. https://www.mdpi.com/2072-6643/7/10/7920

...This comprehensive review outlines how nutrition—including blood sugar regulation—plays a key role in brain aging and the risk of neurodegenerative diseases like Alzheimer’s.