The decline in cognitive ability and memory for an increasingly older population is a major health issue. Along with aging, deskbound lifestyles and poor nutrition habits are among the root causes for cognitive decline. In order to combat this, new dietary solutions are being explored, and traditional ingredients associated with cognition re-examined.
Along with physical and cognitive activity, engaging with a healthy diet is a third modifiable lifestyle factor that has been linked to overall brain health and attenuated cognitive decline. One diet in particular, the Mediterranean Diet (characterized by high intake of fruits, vegetables, whole-grain cereals, fish, nuts, and olive oil), has received particular attention across more than two decades of studies and discussion.
The benefits of adherence to this type of diet have been evidenced in both epidemiological studies and clinical trials and include reduced risk for developing cancer, metabolic syndrome, and vascular disease, as well as lower incidence of dementia. For example, results from the “Prevencion con Dieta Mediterranea” (PREDIMED) study showed risk of stroke—a major factor in cognitive impairment—was reduced by 46% during the study’s 4.8-year follow-up period (median follow-up time) in participants who followed a Mediterranean-style dietary pattern that included 30g of mixed nuts (7.5g hazelnuts, 7.5g almonds, 15g walnuts) per day.
In a 2014 study at the Department of Public Health and Wellness of Andrews University, lead researchers Peter Pribis, PhD, and Barbara Shukitt-Hale, PhD, reported that, in a subsample of the participants tested for neuropsychological function, higher intakes of olive oil, coffee, walnuts, and wine were associated with better global cognition and memory function. Walnuts, in particular, were linked to better working memory function.
Berries, and other blue, red, and purple fruits and vegetables, are high in polyphenolic compounds, especially anthocyanins, which contribute toward brain health and preserve cognitive function in aging. One large epidemiological study concluded that high consumption of berries, such as blueberries, strawberries, and blackberries, delayed symptoms of cognitive aging by 2.5 years. Much of this benefit comes from antioxidant actions.
The beneficial health effects of blueberries are among the most widely studied. Anthocyanin compounds are able to cross the blood-brain barrier and react directly with the tissue of the brain itself. In animal studies, blueberry supplementation appears to reduce nuclear transcription factor κB, a marker of oxidative stress and inflammation. Blueberry compounds also appear to enhance activation of the cAMP response element binding protein (CREB), which is pivotal for maintaining neuronal plasticity.
Blueberry anthocyanins also increase brain-derived neurotrophic factor (BDNF), a nerve-growth protein that supports neuronal survival and neurogenesis. Supplementation in animals in bench studies correlated closely with increased memory performance. While the study of the effects of anthocyanins in humans is limited to a couple of small-scale studies, the results of the animal models show promise for improving learning, and episodic and spatial memory in older adults with mild cognitive impairment.
The compound resveratrol, a phytoalexin antioxidant found in the skin of red grapes and, hence, red wine also shows potential for preserving brain health. Research in vivo has revealed an impressive list of effects due to this powerful polyphenol also found in blueberries, as well as in cranberries, cocoa (and dark chocolate), and even peanuts and pistachios.
Resveratrol has demonstrated anti-inflammatory, antiviral, and antioxidant properties that not only could support cognitive performance, but also protect against the development of cancer and cardiovascular disease; improve insulin sensitivity; and even increase longevity.
In the brain, resveratrol offers neuroprotection by increasing cerebral blood flow (CBF) and perfusion. In mouse studies, it also attenuated the formation of beta-amyloid placque associated with Alzheimer’s disease. It must be noted that the cited effects might be due, in part, to the cognitive testing paradigms used or the bioavailability of the parent compound. To date, studies assessing the effects of resveratrol on cognition in older adults with cognitive impairment have yet to be conducted.
Phytochemical micronutrients that are ubiquitous in the diet are predominantly found in fruits and vegetables, as well as coffee, tea, soy, red wine, and chocolate. Basically, they are in any plant food or in foods derived from plant sources. Because of this, other dietary components have been investigated and show promise for promoting brain health.
Of these, there has been rapidly growing interest in dietary nitrate, found in high concentrations in red beets, as well as lettuce and spinach. Dietary nitrate is reduced to nitric oxide in the body, where it acts as a cellular-signaling molecule that promotes endothelial function. A depletion of nitrate is observed in aging and could be a contributing factor to cerebral hypoperfusion—commonly associated with cognitive decline.
Beets, either as juice or in supplement form, have attenuated oxidative stress and inflammation in animal in vitro studies. Positive effects on endothelial function in humans also were observed with beets.
Two recent intervention studies revealed differing effects of acute beet juice consumption on CBF in the prefrontal cortex in older and younger adults. Increased perfusion in this area also was observed in older adults at rest, while reductions in local CBF during completion of cognitive tasks was observed in younger adults.
In the latter study, conducted in 2014 by Thompson, et al., concurrent improvement on one of the cognitive tasks was observed, leading the authors to suggest it as potentially indicative of a positive effect of dietary nitrate on neural efficiency. Whether the observed increased cerebral perfusion in older adults is associated with similar improvements in cognitive performance remains to be studied.
The aforementioned polyphenol class of phytochemicals are prime examples of nutraceutical workhorses found in produce. Despite their diversity, many of the beneficial physiological effects resulting from consumption of polyphenolic compounds are common across the class. These include promoting vascular function, reducing inflammation, combating oxidative stress, and enhancing neuroprotection, all of which contribute to the maintenance of brain health during aging.
For example, the helpful attributes of cocoa flavan-3-ols (flavanols) have been well-documented. At the epidemiological level, their consumption is associated with lower blood pressure and increased peripheral blood flow, and inversely related to incidence of cardiovascular disease in late adulthood.
Studies on young adults demonstrated improved cognitive function during demanding tasks following an acute dose of 520mg cocoa flavanols, and in older adults following an 8-week dietary intervention with both high (993mg/day) and intermediate (520mg/day) doses of the compound. However, null effects have been reported in other studies. Still, dark chocolate benefited greatly from the majority of studies demonstrating at least some possible beneficial attributes.
Herbs, spices, and their extracts—apart from adding unique flavor—also are known as medicinal plants. These are dried, fragrant aromatic plant substances that contribute taste to foods and beverages, and whose primary function is seasoning rather than nutrition. As medicinals, some are particularly known to boost brain functions and cognitive abilities.
Spices are rich in antioxidants and also are GRAS. The application of such plant-originated ingredients that possess antioxidant and antimicrobial properties might be advantageous in reducing economic losses. They can add to the shelflife of products, as well as provide brain-boosting effects. Although the standard doses of herbs and spices have not yet been established, marketers and consumers should approach the benefits from a whole-diet effect.
Black pepper (Piper nigrum) is one of the most commonly used spices all over the world and, among other strong medicinal benefits, has possible brain-boosting effects. It contains a particularly well-studied compound called piperine that increases brain activity and is able to boost overall cognitive function. It also helps prevent the breakdown of serotonin and has been proven helpful in treatment of neurological conditions like Parkinson’s disease.
Cinnamon is one of the more comprehensively studied spices, when it comes to medicinal value, with widely documented benefits across a spectrum of disease states. It is an anti-inflammatory and anti-tumerogenic, antimicrobial, and antiviral agent with strong antioxidant power. Cinnamon has received intense scrutiny for its ability to help manage blood glucose levels, as well.
As far as brain health is concerned, cinnamon has displayed a potential to treat Alzheimer’s disease by stabilizing the microtubules in the brain. When these microtubules become defective, they can be a causative factor in the development of dementia.
Cinnamon also could improve brain functioning by reducing stress, depression, and anxiety. It also is considered a possible treatment to enhance cognition in the elderly and people with dementia.
Cloves, too, are a common spice with a rich history of traditional use as medicine. And, like cinnamon, it has multiple health capacities for protecting against cancer and cardiovascular disease, and also is a powerful antimicrobial agent. Clove oil common as a topical analgesic, even in Western medicine. Its powerful antioxidant capacity to reduce free-radical formation and improve mental ability is coupled with its reputation as a mental stimulant that can improve attention and alertness.
Nutmeg, another popular spice in the Western pantry, contains myristicin, a compound shown to improve cognitive ability and overall brain activity, and to inhibit specific enzymes that have been linked to the development of Alzheimer’s disease.
The triumvirate of cinnamon, cloves, and nutmeg make a tempting group for pastry manufacturers already including them in products, such as cookies, sweet rolls, spice cakes, and fruit pies.
Many botanical plants, both common and less so, are used to maintain cognitive function and brain health. Adding these to one’s diet is beneficial for health and proper brain functionality. Many can be added easily to salads, soups, casseroles, drinks, and other dishes; or used as teas or extracts. Some are believed to greatly improve cognitive skills and support healthy brain function in consumers of all ages.
But, it takes more than pizza to boost brain power. As with spices, the phytochemicals in herbs are part of a cumulative approach to incorporating better-for-you compounds into the diet. Oregano (Origanum vulgare) has excellent antioxidant activity and can prevent free-radical damage to brain cells during the aging process. It plays important role in improving learning abilities, concentration, mood, anxiety, and sleep as well.
Oil extracts of thyme (Thymus vulgaris) are rich in omega-3 fatty acids, which provide protection against cognitive decline due to aging, and also can improve the mind’s capacity for memory and learning.
Rosemary’s (Rosmarinus officinalis) antioxidant and antimicrobial capacity have made it the new favorite source for natural food preservation and safety. Rosemary compounds also improve overall brain health, due to their preventing free-radical damage to the brain, as well as having anti-inflammatory properties. Rosemary particularly is good at reducing the chance of developing a degenerative condition, such as Alzheimer’s, or of having a stroke.
The antioxidants present in sage (Salvia officinalis) also help prevent in the free-radical formation in neural tissues, and boost cognitive function and memory recall. Sage also contains a compound which has been shown to prevent the breakdown of essential neurotransmitters. Holy basil (Ocimum tenuiflorum), also known as tulasi, is commonly used in Southeast Asian, Himalayan, and Indian cuisines. It is becoming better known in the West, as the cuisines of these regions increase in popularity.
Holy basil got its name from Ayurvedic medicine as a powerful curative plant, able to boost brain function by improving circulation and blood-flow to the brain. It has been shown to improve cognitive skills, memory, concentration, and attention, and can improve the body’s response to stress.
Two plants, Bacopa monnieri and Sceletium tortuosum, are new, impressive providers of healthful benefits, especially for cognition. Bacopa has a traditional history as an antipyretic, sedative, and analgesic, and can contribute to memory enhancement and cognitive performance.
Sceletium has been used to enhance mood, promote relaxation, and even create feelings of euphoria. Traditionally, the roots and leaves are fermented and chewed. It has been smoked, used as snuff, or made into a tea or tincture. However, its extracts readily can be incorporated into supplemental beverage shots or other vehicles.
Among the roots and root-like plant ingredients for health, many have strong scientific support for health benefits. Turmeric (Curcuma longa) has become the darling of better-for-you beverage makers. It’s active compound, curcumin, joins the above spices, as well as its fellow rhizome cousins, ginger and galangal, as well-documented cornerstones of traditional medicine.
Compounds in turmeric have been shown to reduce the build-up of plaque in the brain that can lead to Alzheimer’s disease. A recent study revealed that turmeric improves memory and reduces the effects of stress. Compounds in turmeric also can improve blood flow; help move glucose to the brain; and reduce inflammation—all of which can improve cognitive function.
Rhodiola (Rhodiola rosea), also called goldenroot, is used for increasing energy, stamina, strength, and mental capacity. It is believed to help the body better adapt to physical, chemical, and environmental stress, and for improving athletic performance; strengthening the nervous system; and helping with depression.
Ginseng (Panax ginseng, etc.) is enjoying a resurgence, after all but disappearing from the functional beverage scene for a number of years. Sometimes added to foods as well, ginseng has been studied as a way to improve mood and build memory. Kava (Piper methysticum) also is the subject of new attention, having a long history as an herbal anti-anxietal and soporific. It’s been used for other nerve issues, such as restlessness and stress-related symptoms, such as muscle tension or spasms.
Kava does not interfere with mental sharpness. When taken for sleep problems, kava promotes deep sleep. However, there still are controversies associated with it, due to its active compounds—kavalactones—having a tendency to interfere with other medications and even cause liver problems when overused or used in conjunction with alcohol. Still, the science supporting the anecdotal traditions has turned out to be unusually strong.
Omegas for Thinking
Omega-3 polyunsaturated fatty acids (PUFAs) are long-chain lipid compounds found in algae, seaweed, marine animals, nuts (especially walnuts), seeds (including chia, flax, hemp, and others), and some produce (such as olives and avocados). These essential fatty acids are among the most studied healthful ingredients known, with a long history of playing essential roles in cognitive ability, too.
The key omega-3s in use in foods and beverages, as well as supplements, are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). There is strong evidence that adequate omega−6:omega−3 ratio could be beneficial to health because of increased antioxidant, anti-inflammatory, and anti-arrhythmic functions.
Multiple studies show reduced intake of omega-3s is associated with increased risk of age-related cognitive decline or dementia, including Alzheimer disease. Scientists believe the omega-3 fatty acid DHA is especially protective against Alzheimer’s and dementia. DHA, in particular, is uniquely accumulated in the tissue of the central nervous system, and its presence beneficially impacts upon plasma membrane function, synaptic transmission, and cellular signaling.
Recent MRI studies have indicated that higher circulating levels of omega-3 PUFAs are associated with reduced white matter damage and grey matter atrophy—outcomes that also were shown to improve, along with executive function, following a 6-month dietary intervention of 2.2g/day EPA+DHA in healthy 50-75-year-olds. Underpinning these effects are the many actions of DHA and EPA in the brain.
A number of neuroprotective properties of DHA and EPA exhibit an ability to improve brain health. These include attenuation of inflammatory responses by suppressing pro-inflammatory pathways and up-regulating pro-resolving mediators, such as neuroprotection; or by modulating mitochondrial function and reducing oxidative stress.
In addition to these mechanisms, human and animal studies both suggest that dietary supplementation with omega-3 PUFAs improves regional CBF, which contributes to the preservation of both brain structure and function. Results from animal research on adult hippocampal neurogenesis, which declines with age, indicate that neurogenesis appears to be stimulated with omega-3 supplementation and with concurrent improvements in cognitive function.
While supplementation studies in healthy adults have been less conclusive, two recent meta-analyses revealed that supplementation with omega-3 PUFAs has a beneficial effect on episodic memory in subjects characterized as suffering from mild memory complaints and a marginal effect of on working memory in subjects with low baseline omega-3 PUFA status.
Functional foods containing omega-3s are one of the fastest growing food product categories in the US and Europe. A prerequisite for successful development of foods enriched with lipids containing PUFAs is successful prevention of oxidation. Lipid oxidation and antioxidant mechanisms in multiphase food systems are highly complex, and multiple factors can influence the rate and extent of lipid oxidation and, thus, the efficacy of different antioxidants in such systems.
The specific effectiveness of a diet designed for healthy cognition and memory is of great interest. The intake of fats, proteins, and micronutrirents must be considered with a whole-diet approach, and the possibility of interactions and synergies explored, as well.
All available evidence suggests consuming foods and beverages heavy in components and ingredients typical to the Mediterranean-style diet, including high amounts of omega-3 fatty acids, is beneficial for preserving brain health and function, especially during aging.
Originally appeared in the July, 2016 issue of Prepared Foods as Brain Boosters.