Many Plant-Based Foods Are Neuroprotective
Since first characterized by Dr. Lois Alzheimer in 1906, Alzheimer’s disease has claimed the lives of millions of people. According to the Mayo Clinic and others, most cases of Alzheimer’s disease are preventable. Unfortunately, this deadly disease is not curable, yet.
Neurodegenerative disease is now the fastest-growing cause of death in the world. It’s a cruel wasting disease that takes both the mind and body. Many cases of cancer and heart disease are proving to be treatable and beatable, while millions of people around the world are dying from this family of incurable wasting diseases. What is going on?
First of all, Alzheimer’s disease, Parkinson’s disease and Creutzfeldt-Jakob disease (CJD) are all forms of prion disease. The main difference between Alzheimer’s disease and Parkinson’s disease is the region of the brain initially impacted by prion infection. The difference between CJD and Alzheimer’s disease is the severity of the prion infection and the stage of disease progression. As one neurologist explained, CJD is like Alzheimer’s disease on steroids.
Prion disease is technically known as transmissible spongiform encephalopathy (TSE). As the name suggests, prion disease is transmissible.
Therefore, prion aversion in your lifestyle influences whether or not you will contract neurodegenerative disease. Prion disease in humans is so transmissible that wildlife around the world have now contracted prion disease from human waste. Cities are dumping millions of tons of infectious waste on crops, ranches, forests, parks, golf courses, school grounds, and beyond. These practices and others have created a public health disaster around the world.
In wildlife, prion disease is known as chronic wasting disease. In livestock, prion disease is known as mad cow disease. It’s all essentially the same, except for the fact that there are thousands of different mutations spreading rampantly and there are more mutations made every day. Humans are spreading the disease into the environment in numerous ways, while Mother Nature feeds them right back to us through the food chain and our water supplies.
As such, the food and water that we consume are very important factors. The right foods can help us avert Alzheimer’s disease. The wrong foods and beverages increase our risk.
A strong heart is a critical factor as we defend our brains. Strong blood flow helps keep the brain healthy.
Elevations in cardiovascular risk factors during the midlife period, including high cholesterol, hypertension, obesity, and diabetes, increase the risk for Alzheimer’s disease and Parkinson’s disease. Individuals with high cholesterol have a risk more than 70 percent greater, while diabetes and high blood pressure carry a 30-40 percent greater risk. A study showed that individuals who were overweight before age 65 had a roughly 40 percent greater risk for dementia.
Many studies suggest that what we eat affects the aging brain’s ability to think and remember. These findings have led to research on general eating patterns and whether they might make a difference.
Animal products are more highly correlated with Alzheimer’s disease than any other type of foods. The prospective Chicago Health and Aging Project reported that persons consuming the most saturated fat (compared with the least) had more than twice the risk of developing AD, with similar findings for trans fats. Saturated fat is particularly abundant in dairy products and meat. Trans fats are found in many snack foods and, in traces, in dairy products. Other studies have also implicated saturated fats in the cognitive decline that precedes AD.
Margarine and Frosting: These foods, along with many packaged snack foods, are high in trans fats. You may know that trans fats aren’t good for your heart and blood vessels. Research has found that they may also wreak havoc on brain function. A study from the journal Neurology found that older adults who had the highest levels of elaidic acid (a common type of trans fat) in their blood were the most more likely to develop dementia.
Doughnuts: These tasty treats are both fried and loaded with sugar, a bad combo when it comes to brain health. You get an inflammation double-whammy from the deep frying process and the excess sugar. Studies have linked high levels of sugar in the blood with dementia. Even worse: Most doughnuts contain trans fats, another ingredient your brain doesn’t need.
White Bread and White Rice: Refined carbohydrates, even ones that don’t taste super sweet, can spike your blood sugar. That’s often followed by a crash, which can make you feel mentally foggy. Research shows that too many refined carbs may increase your risk of Alzheimer’s disease, especially in certain people who are genetically predisposed to it. Go for whole-grain breads, brown rice, and whole-wheat pasta when you eat carbs.
Red Meat: It’s high in saturated fat, which is bad for your heart as well as your brain. In fact, limiting red meat is a key tenet of the MIND Diet, a research-based eating program aimed at keeping your memory and thinking sharp. Want a protein source that’s better for your brain? Fish, lean poultry, and beans are healthier options.
Butter and Full-Fat Cheese: That creamy taste comes at a cost. These dairy products are full of saturated fat. Followers of the MIND diet avoid butter, cheese, and other full-fat dairy. When it comes to brain health, low-fat dairy is generally the healthier choice. You can get milk, yogurt, cottage cheese, and other dairy foods in low-fat forms.
Swordfish and Ahi Tuna: Most health experts are big fans of fish, but the kind they love is salmon and others that contain a healthy fat called omega-3 fatty acids. Swordfish, ahi tuna, and other big fish lose points because they tend to be high in mercury. That’s a neurotoxin — meaning toxic to your brain — that may lead to higher risk of memory loss and poorer thinking skills in older adults.
Bottled Dressings, Marinades, and Syrups: Read the ingredients on the label carefully. Many of these products have surprisingly large amounts of high-fructose corn syrup. That’s the same stuff that’s in soda. It’s linked to a variety of health problems, including memory loss and a decline in brain performance. Try mixing up your own salad dressings instead.
Beverages: If you want to keep your brain sharp as you age, steer clear of super-sweet drinks. Research has found that people who drink a lot of soda, sweet tea, and other sugary beverages are a lot more likely to have memory trouble. These drinks, which often have a type of sugar called fructose, might even cause certain parts of your brain to become smaller. Research finds that people who sip at least one diet soda a day are nearly three times as likely to have a stroke or develop dementia. Scientists think that artificial sweeteners are a contributing factor.
Processed Foods: People who eat a lot of fried, processed foods tend to fare worse on tests that measure thinking skills. The likely reason: fried and fatty foods. These guilty pleasures cause inflammation, which can damage the blood vessels that supply the brain with blood and hurt the brain itself. The mechanism may relate to the influence of dietary fat on blood cholesterol concentrations. As noted above, midlife hypercholesterolemia is associated with risk for AD. Cholesterol forms the core of the plaques that build up within the brain. Oxidized cholesterol, found in ghee, powdered milk, meat, cheese, and eggs, has also been suggested as a contributor to AD due to its apparent ability to cross the blood-brain barrier, leading to inflammation and free radical formation. In addition, animal products are chief dietary sources of compounds that are thought to play a role in the pathogenesis of AD.
The Mediterranean diet emphasizes fruits, vegetables, whole grains, legumes, fish, seafood, unsaturated fats such as olive oils. It discourages red meat, eggs, and sweets.
A variation of this, called MIND (Mediterranean–DASH Intervention for Neurodegenerative Delay) incorporates the DASH diet, which lowers high blood pressure—a risk factor for Alzheimer’s disease.
The MIND diet includes plant-based foods known to contain properties that prevent dementia. It encourages 10 food groups:
- Leafy green vegetables, at least 6 servings/week
- Other vegetables, at least 1 serving/day
- Berries, at least 2 servings/week
- Whole grains, at least 3 servings/day
- Fish, 1 serving/week
- Poultry, 2 servings/week
- Beans, 3 servings/week
- Nuts, 5 servings/week
- Wine, 1 glass/day
- Olive oil
The MIND diet limits servings of red meat, sweets, cheese, butter/margarine and fast/fried food. While scientists aren’t sure yet why the Mediterranean diet helps the brain, its effect on improving cardiovascular health might in turn reduce dementia risk. Eating fish may be the strongest factor influencing higher cognitive function and slower cognitive decline. In contrast, the typical Western diet increases the risk for cardiovascular disease, which contributes to mental decline.
In addition, the Mediterranean diet might increase specific nutrients that may protect the brain through anti-inflammatory and antioxidant properties. It may also inhibit beta-amyloid deposits, which are found in the brains of people with Alzheimer’s or improve cellular metabolism in ways that protect against the disease.
In contrast, higher intakes of unsaturated fats and a higher ratio of unsaturated to saturated fat are associated with a significantly lower risk for either cognitive decline or AD. A meta-analysis of fish and omega-3 fatty acid intake found that higher compared with lower intake of fish was associated with a 36 percent lower risk of AD.
Both longitudinal studies and meta-analyses have revealed cognitive benefits from what is referred to as a Mediterranean diet. Definitions of such a diet vary from one study to another, but the diets are generally lower in animal products, higher in plant-derived foods, and may include some oil, wine, or other regional products. Studies have shown a similar benefit from both traditional Japanese diets and diets that focused on higher intakes of vegetables, fruits, nuts, fish, and poultry and a lower intake of high-fat dairy animal foods. Soy foods, frequently used in Asian cuisine, may be particularly beneficial as a replacement for animal products. They are free of cholesterol, lower in saturated fat than animal products, and have also been associated with benefits on cognitive function in postmenopausal women.
Presumed explanations for the benefits of these diets include their low content of saturated and trans fats, their high content of antioxidant-containing foods, and, in Mediterranean regions, the use of olive oil, which contains oleocanthal, a phytochemical that appears to inhibit the fibrillization of tau protein, deposits of which are a characteristic of AD.
The Chicago Health and Aging Project reported that, in older people followed over a 4-year period, AD developed in 14.3 percent of those whose vitamin E intake was low, but in only 5.9 percent of those in the highest category of dietary (non-supplement) vitamin E. Similarly, in a Dutch study including 5,395 people aged 55 and older, those who got the most vitamin E cut their risk of developing AD and other forms of dementia over the next decade by about 25 percent.
Studies have shown that patients with AD and cognitive impairment have lower blood levels of all forms of vitamin E found in foods when compared with cognitively normal persons. While each form shows different biological properties that may offer neuroprotective effects in AD. A controlled clinical trial of high-dose vitamin E found a significant benefit for AD patients.
Many foods — blueberries, leafy greens, and curcumin (found in the spice turmeric), to name a few — have been studied for their potential cognitive benefit. These foods were thought to have anti-inflammatory, antioxidant or other properties that might help protect the brain. So far, there is no evidence that eating or avoiding a specific food can prevent Alzheimer’s disease or age-related cognitive decline.
But scientists continue to look for clues. One study, based on older adults’ reports of their eating habits, found that eating a daily serving of leafy green vegetables such as spinach and kale was associated with slower age-related cognitive decline, perhaps due to the neuroprotective effects of certain nutrients. Research has also shown that eating a diet that includes regular fish consumption is associated with higher cognitive function and slower cognitive decline with age. Another recent study, in mice, found that consuming a lot of salt increased levels of the protein tau, found in the brains of people with Alzheimer’s, and caused cognitive impairment.
New research finds that it’s not only what you eat, but also how you combine certain foods that can increase your risk of developing Alzheimer’s and other forms of dementia in later life. The foods most strongly associated with this risk were sugary snacks, alcohol, processed meats, and starches like potatoes.
Increased Vitamin C: Studies have found that blood levels of vitamin C were lower in patients with both mild cognitive impairment and AD, when compared with controls. In addition, individuals with higher vitamin C intakes (through diet and low-level supplementation of 500 mg/day or less) may have slower rates of cognitive decline than do persons with low intakes, thereby raising the possibility that long-term consumption of diets high in vitamin C-containing foods can reduce the risk for AD.
In AD patients, no benefit was found in a 16-week study of a combination of vitamin C and E, lipoic acid, and Coenzyme Q10. In contrast, a study in which AD patients were given a combination of an antioxidant (lipoic acid) and an omega-3 supplement over 12 months resulted in less decline in the Mini-Mental State Examination (MMSE) and Instrumental Activities of Daily Living.
Micronutrient Adequacy: A systematic review and meta-analysis found that AD patients had significantly lower blood levels of vitamins A, B12, C, E, and folate and non-significantly lower levels of vitamin D and zinc when compared with individuals without AD. Similar results were found even in AD patients who were not considered malnourished. Given the large number of nutrients AD patients are lacking, a multiple vitamin supplement may be of benefit, provided it omits iron and copper, as noted below.
Avoiding Excess Copper: A meta-analysis examining copper levels in serum, plasma, and cerebrospinal fluid concluded that AD patients have a higher body copper burden than do normal individuals. In addition, a higher than normal amount of this copper is unbound from its carrier in these patients, as a result of alterations in copper metabolism seen in AD patients. The consequence, apparently, is an increase in unbound copper in the brain. This is of concern because brain copper increases with age and influences the expression of the amyloid beta precursor protein and increases the aggregation and neurotoxicity of Aβ.
Avoid Excess Iron: Some evidence suggests that excess iron may contribute to AD risk. Patients with AD have elevated iron levels in several brain areas affected by this disease, and an excess of iron in the brain is associated with beta-amyloid (Aβ) plaque formation. Iron transport through the blood-brain barrier is usually tightly controlled. However, a damaged blood-brain barrier has been implicated in the development of this disease and may precede the development of clinical symptoms. A Western diet has been linked to a compromised blood-brain barrier, thereby providing a possible mechanism by which iron could accumulate in the brain. In the AD Neuroimaging Initiative cohort study, ferritin levels predicted the conversion from mild cognitive impairment to AD.
Adequate Vitamin D Intake: Vitamin D deficiency is associated with global cognitive impairment in adults, and a meta-analysis found the risk to be more than 20 percent greater for AD and dementia in persons whose vitamin D blood levels were deficient. In addition, patients with AD are significantly more likely to have vitamin D deficiency than normal individuals.
Avoiding Aluminum: Aluminum exposures can be neurotoxic, and studies have shown associations between aluminum in drinking water and AD risk. Unlike iron and copper, there is no requirement for aluminum in human biology. Nonetheless, the role of aluminum in AD remains controversial.
Moderate Alcohol Consumption: Although alcohol intake as low as 20 g/day (1.25 servings) is a known risk factor for certain cancers, hypertension, and several other diseases, a meta-analysis found a roughly 30 percent lower risk for AD and a 25 percent lower risk for dementia in light to moderate alcohol consumers, compared with nondrinkers. Benefits of moderate alcohol consumption, if any, are thought to derive from cardiovascular risk factor reduction (reducing platelet aggregation or modifying serum lipids) or through acetylcholine release in the hippocampus. However, hippocampal insulin resistance has been found in patients with AD, and moderate alcohol consumption is known to enhance insulin sensitivity.
Coffee: A 2010 study suggested that coffee might reduce Alzheimer’s disease risk. Over a 21-year period, a study including 1,409 people found that high coffee drinkers had 64 percent less risk of developing Alzheimer’s disease, and benefits were seen even among people carrying the APOE e4 allele. However, a much larger prospective study, including 398,646 UK Biobank participants, aged 37-73 years, showed that high daily coffee consumption was associated with a significant loss of gray matter and increased risk of dementia. Those drinking more than 6 cups per day had a 53 percent increased risk of dementia, compared with those drinking 1-2 cups per day. My guess is that the stimulus to the heart is a positive for the blood flow to the brain, but the chemical interaction is an unknown.
Researchers are learning how the biochemical processes of food intake and digestion interact with changes in the brain. They are finding that the gut microbiome — the community of viruses, bacteria and other microbes in the digestive system — may influence the onset and progression of Alzheimer’s disease. Studies in mice and humans show that the composition of the gut microbiome in Alzheimer’s and mild cognitive impairment is different from that in cognitively normal beings.
Changes in the gut microbiome as people age have been linked to disruptions in the immune system, persistent inflammation and chronic diseases, including neurological disorders such as Alzheimer’s. Researchers are exploring how these changes are related to each other and to brain changes related to Alzheimer’s, including neurodegeneration and the accumulation of toxic proteins beta-amyloid and tau.
Other Risk Factors
Observational studies and clinical trials show that regular aerobic exercise reduces the risk for developing dementia and may reverse shrinkage in the hippocampus and other regions of the brain. Hypertension, declining blood pressure, cerebrovascular and cardiovascular disease, diabetes, smoking and elevated alcohol use are associated with cerebral atrophy. Excess body weight may exacerbate these factors or lead to cerebral atrophy directly.
A history of traumatic brain injury may be associated with development of AD. Reduced sleep quality, sleep problems, and daytime sleepiness are associated with altered AD biomarkers (beta amyloid, tau, and inflammation) in cerebrospinal fluid. Certain genetic abnormalities place some individuals at high risk of early-onset AD.