This week, the U.S. Food and Drug Administration proposed new dietary guidelines that, for the first time, recommend placing a cap on average Americans’ consumption of added sugar.

The recommendations are part of new 2015 Dietary Guidelines, due to be finalized next month, and based on the latest research showing that sugar — not fat, long vilified as a dietary evil — is behind the nation’s rising rates of obesity, diabetes, heart disease, and certain cancers.

But the official pronouncement from the FDA comes as no surprise to nutritional researchers like Dr. David Perlmutter. The board-certified neurologist and fellow of the American College of Nutrition has long argued that sweeteners in soft drinks and processed junk foods are not only fueling millions of Americans’ physical ailments, but are also behind the nation’s rising rates of Alzheimer’s disease.

The good news, he tells Newsmax Health, is dietary changes may be an effective way to stave off the ravages of Alzheimer’s, which now strikes more than 5 million Americans and is expected to afflict three times as many over the next 25 years. And certain kinds of fat in the diet may actually be beneficial for brain health, he notes.

“One of the key ways to help prevent this disease is through diet,” says Dr. Perlmutter, author of the No. 1 New York Times Bestseller, “Grain Brain,” and, most recently, the bestselling book “Brain Maker.”

Specifically, he recommends what he refers to as the “Anti-Alzheimer’s Trio” — grass-fed beef, avocados, and coconut oil. All three foods are high in brain-healthy fats that can help boost memory and cognitive function, and knock down inflammation tied to dementia.

“These items are all low in carbs and high in fat, helping to reduce some of that brain-bullying inflammation — the root cause of so many ailments,” he explains.

Here’s why Dr. Perlmutter argues these three superfoods are critical to maintaining healthy brain function, and staving off memory loss, as we age:

Grass-fed beef. Unlike conventionally raised livestock fed grains, cows fed grass produce meat that is much lower in inflammation-producing omega-6 fatty acids. Inflammation — from sugar, carbs, and certain types of meat common in the typical American diet — increase the risk for Alzheimer’s, as well as heart disease, diabetes, and certain forms of cancer.

Going with grass-fed beef lowers your overall risk from inflammation-inducing compounds found in conventional meat, Dr. Perlmutter says.

“In addition, the corn and grain fed to cattle is overwhelmingly genetically modified, and this introduces worrisome proteins into non-grass fed meat,” he says. “It may sometimes be a bit more expensive, but it’s smarter to buy grass-fed when you can.”

Coconut oil. This common oil is loaded with saturated fats, which actually fats raise HDL (the good) cholesterol and change the LDL cholesterol to a benign subtype. As a result, it can improve your cholesterol levels naturally, which lowers your risk for heart disease and Alzheimer’s

“Specifically, coconut oil is known as a rich source of beta-HBA and is one of our brain’s ‘superfuels,’ ” adds Dr. Perlmutter.

Avocados. A common Mexican food staple, avocados are naturally nutrient-dense and contain around 20 vitamins and minerals. While consuming fruits and vegetables of all kinds has long been associated with health benefits, many studies suggest avocados are particularly helpful in combatting obesity, heart disease, cancer, diabetes, vision loss, and dementia — in part because they have anti-inflammatory properties.

Avocados contain a natural plant sterol called beta-sitosterol that helps help maintain healthy cholesterol levels, lutein and zeaxanthin, — two phytochemicals that are essential to eye health — bone-strengthening vitamin K, and cancer-fighting folate, which also helps combat depression and other mental-health disorders.

In addition to these three foods, Dr. Perlmutter recommends a number of other foods containing ingredients that have been shown to prevent neurodegenerative disorders — including probiotics, prebiotics and fermented foods.

“Probiotics and prebiotics help maintain a healthy balance of bacteria in your gut — this is known as the human microbiome (HM),” he explains.

“Emerging studies indicate that the HM may contribute to the regulation of multiple neuro-chemical and neuro-metabolic pathways through a complex series of highly interactive and symbiotic host-microbiome signaling systems. These systems mechanistically interconnect the gastrointestinal (GI) tract, skin, liver, and other organs with the central nervous system (CNS).”

Dr. Perlmutter says conventional medical practitioners often underestimate the importance of diet in staving off Alzheimer’s.

“The first step to preventing [Alzheimer’s] is consuming the right foods, the second is knowledge,” he says.

Dr. Perlmutter’s comments come as the FDA is proposing new guidelines that recommend Americans limit added sugar to no more than 10 percent of daily calories.

For someone older than 3, that means eating no more than 12.5 teaspoons, or 50 grams, of it a day.

That’s about the same amount of sugar found in a can of soda, but for most Americans, simply giving up sugary soft drinks won’t be enough to meet the recommendations.

Sugar, honey, and high-fructose corn syrup are found in sodas, cookies and candy — but are also in many low-fat foods, yogurt, granola and wholegrain breads, as well as in ketchup, pasta sauce, canned fruit and prepared soups, salad dressings, and marinades.

For decades, fat was the primary dietary evil health experts targeted, with many suggesting it was the primary cause of the nation’s rising obesity levels. But the latest nutritional research shows sugar is a far greater enemy of public health, and that some fats are even good for you.

Dr. Perlmutter recommends taking steps to prevent or even reverse autoimmune responses and disorders, including Alzheimer’s. Your physician can order blood tests, like those from Cyrex Laboratories, that can help your physician determine if you are having an autoimmune response to environmental triggers like food, chemicals, or other substances.