It's a sad fact: The average American gets more than half of his or her daily calories from junk food. These ultra-processed foods are high in calories, salt, empty carbohydrates, sugar, and bad fats — and low in everything else, like fiber, needed for proper nutrition.

The impact of all that junk food on your waistline is clear. What's less visible but just as severe is the impact of all that junk food on your brain.

Poor nutrition ages your brain and opens the door to age-related cognitive decline. And the damage starts long before the first symptoms appear.

In fact, a diet high in junk food causes oxidative stress and inflammation throughout the body, including the brain.

A diet high in junk food also shifts your gut microbiome in an unhealthy direction, triggering aging processes that damage the brain and may lead to neurodegeneration.

Fortunately, the accelerated brain aging caused by a poor diet can be reversed, at least in part, by ditching the junk food in favor of a Mediterranean-style diet. This is a dietary approach that numerous studies have shown to be associated with a lower risk of mild cognitive impairment.

The neuroprotective foods of the Mediterranean diet include fish and other foods rich in omega-3 fatty acids, a range of colorful plant foods, and whole grains. What's not included? Red meat, cheese, fried foods, highly processed foods, and sugar.

Of all the foods that help reverse brain aging, those high in omega-3 fatty acids top the list. Why? Because omega-3s are crucial for building and maintaining your body's cell membranes, including the membranes that protect the 80 billion neurons in your brain.

When neuron membranes are strong and flexible, the neurons connect and communicate efficiently. They form and retain memories easily, keep you on an even emotional keel, and maintain your cognitive function.   

Coldwater oily fish are the best source of omega-3 fatty acids. Aim for at least four servings a week of SMASH fish: salmon, mackerel, anchovies, sardines, herring.

Despite the clear benefits of eating fish, it's just hard to manage that many fish servings a week consistently. To be sure you're getting enough omega-3 fatty acids, consider a daily fish oil supplement. The Brain Benefits liquid formula is an excellent source of the omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) — the two essential fats that are primary structural components of brain cells. Both are key to maintaining the integrity of neuron membranes.

DHA and EPA are also crucial for supporting the structure and function of the microglia cells — the brain's clean-up crew. These cells remove debris, including the amyloid proteins related to Alzheimer's disease, from the brain.

Keeping these cells functioning well is essential for avoiding cognitive decline.