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In the Whole Detox book, colors are connected to body systems. The combination of blue and purple colors represents the INSIGHT System, which includes the brain. The brain is the center of the nervous system: it maintains centralized control over the other organs in the body and regulates sensory information and muscle activity. The brain also controls the secretion of hormones, which act as chemical messengers allowing different body parts to communicate. A healthy brain allows a person to make sense of the world, remember, learn, play, and focus. It also allows them to manage information, use judgment, and maintain logic and perspective. When brain health is impaired, there can be mood imbalances, such as depression and anxiety; problems with cognition, focus, and memory; and issues with muscular movements and balance.

Blue-purple Plant Foods

Blue and purple plant foods are rich in antioxidants, especially those that act to protect the brain and nervous system from oxidative stress and inflammation caused by free radical damage. Anthocyanins are a group of water-soluble polyphenolic compounds that make up the deep blue and purple pigments found in plant foods. They are rapidly absorbed and can cross the blood-brain barrier to exert their benefits on brain cells. While the bioavailability of anthocyanins is low, they are transported to the brain where they can concentrate. Furthermore, the metabolites produce an abundance of biological effects, including antioxidant and anti-inflammatory activity and neurological protection.

Brain-Gut Axis

Brain health is largely impacted by the health of the gastrointestinal microbiota. The signaling pathway, referred to as the gut-brain axis, facilitates a line of communication between gut bacteria and the central nervous system. The signaling system impacts neuroimmune and neuroendocrine signaling, and the species of bacteria present dictate whether the messages sent are health-promoting or disease-promoting. The species in the microbiome communicate with the brain and directly impact the messages from the hypothalamus to the rest of the body. Disease-promoting bacteria will communicate with the brain and send messages that can activate the immune system. These messages are responsible for neuro-inflammation that triggers systemic inflammation.

Because of the relationship between gastrointestinal microbiota and the central nervous system, it is important to learn how to promote health within the gut, which involves encouraging the growth of health-promoting bacteria and preventing the growth and presence of disease-promoting bacteria. Polyphenols, which include the subcategory of flavonoids, have a beneficial impact on the microbiota. Anthocyanins, a subclass of flavonoids, can impact the diversity of bacteria present in the microbiota.

Part of the neuroprotective effects of anthocyanins is due to the high oxygen radical absorption capacity (ORAC) value. Anthocyanins can scavenge free radicals but also increase the body’s production of its innate antioxidant enzymes: superoxide dismutase, catalase, glutathione peroxidases, and glutathione levels. However, anthocyanins have a low absorption rate, and their metabolites produced in interaction with the microbiota are more bioavailable.

The most profound effects anthocyanins demonstrate are mobilized by the interaction within the microbiotic environment, where the polyphenolic compounds produce more bioavailable metabolites. Furthermore, the metabolites produced within the microbiota modulate the gut bacteria species present. This change in microbial population impacts communication between the gut and the central nervous system. Anthocyanins may alter the macrobiotic environment to prevent the progression of age-related neurological disorders because the metabolites produced by anthocyanins support the growth of beneficial bacteria. These beneficial bacteria promote communication between the gut and the brain through the enteric nervous system, giving anthocyanins additional neuromodulating effects that may prevent neurological and systemic inflammation. Additionally, within the microbiota, anthocyanins are able to regulate the production of tryptophan (related to serotonin production) and short-chain fatty acids, as well as modulate the production of toxic lipopolysaccharides.

The complex and multidimensional biotransformation process that occurs metabolically with blue and purple foods make these plant compounds powerful neuroprotective agents with dynamic health-promoting and disease-preventing capabilities.

Anthocyanins have four routes of physiological effects:

• reduce systemic inflammation by impacting the messages sent through the gut-brain axis;
• encourage the growth of health-promoting bacteria in the gut, reduce gastrointestinal inflammation, modulate health-promoting compounds, and attenuate the production of toxic compounds;
• provide neurological antioxidant effects through their ability to cross the blood-brain barrier and concentrate in different compartments;
• impact neuroinflammatory communication directly within the brain.

Did you know?  

• Anthocyanins are members of the flavonoid family of phytochemicals, and they may improve vascular function, blood flow, and cognitive function.
• Consuming blueberries and strawberries is associated with a slower risk of cognitive decline, and blueberry intake is associated with benefits in memory.
• Anthocyanins may help maintain thinking and memory by reducing inflammation and by inhibiting DNA damage in the brain.
• Blueberry juice contains polyphenols and anthocyanins and may act as a potent antioxidant to help protect your brain against oxidative stress and the damage it can cause.
• Regular consumption of strawberries and blueberries combined with vitamin E may lower the risk of Parkinson’s disease.
• Consuming 200 mL of cherry juice daily has the potential to improve language and memory, as well as reduce systolic blood pressure.

Major sources of anthocyanins include blueberries, cherries, strawberries, raspberries, purple grapes, black currants, red cabbage, and red onion, in addition to the fruits and vegetables listed below.

Blue-purple Fruits

Blueberries

• Adding blueberries to your diet (about 1 cup of fresh blueberries) may help improve some aspects of cognition.
• Phytochemicals found in antioxidant-rich foods like blueberries may serve to help reverse the course of neuronal and behavioral aging.
• Regular blueberry intake can prevent cognitive decline and improve the effects of stress on the brain.
• Researchers reported that daily consumption of blueberry powder equivalent to ½ cup of whole fruit for 12 weeks could improve executive control functions and reduce fasting insulin levels.
• Blueberries and anthocyanins reduce susceptibility to neurological decline but also cardiovascular disease and type 2 diabetes mellitus.
• Select blueberries that are firm and not mushy or with the skin broken. When shaking the container, the berries should move around freely rather than sticking together. Ensure they are free of moisture (and mold), which can cause them to spoil.
• When buying frozen blueberries, shake the bag to ensure the berries are loose and not stuck together, possibly indicating they were damaged in some way.
• Buying frozen blueberries is a great way to reap the benefits of blueberries when fresh berries are unavailable. Frozen blueberries provide comparable amounts of antioxidant effects and active anthocyanin levels. Drying the fruit, however, will reduce their total anthocyanin level by 41%, and dehydrating will reduce levels by 49%.

Blackberries

• Blackberries are rich in anthocyanins and may counteract neuroinflammation caused by a high-fat diet.
• Supplementation with blackberry extract may modulate species of bacteria in the gut that will promote the release of neuroprotective metabolites.
• Because of the compartmentalized structure of blackberries and raspberries, they are high in fiber. Adults are recommended to consume 25-35 grams dietary fiber daily.
• One hundred grams of blackberries contain 3 grams and raspberries, 6.5 grams of fiber. Strawberries and blueberries contain about 2 grams of fiber per 100 grams.
• Blackberries contain 10 different types of phenolic acids.
• Fully-mature blackberries have the highest antioxidant capacity and highest levels of anthocyanins and magnesium.

Black raspberries

• A diet rich in black raspberries may reduce intestinal inflammation.
• Black raspberry extract may be protective against the effects of alcoholic liver disease (ALD) and may reduce elevated levels of liver enzymes that present with ALD.
• Black raspberries contain vitamin A, C, E, calcium, folic acid, and are a good source of fiber with appreciable levels of anthocyanins (e.g., ellagic acid, ellagitannins, and ferulic acid).
• A rodent study examining the effects of a diet supplemented 7-13 mg of anthocyanins per day sourced from freeze-dried black raspberry powder, which suppressed levels of proinflammatory cytokines and increased levels of the health-promoting bacteria.
• Oregon is the largest producer of commercial black raspberries, and they can be found wild in the summers of New England.

Bilberries

• One of the most abundant sources of anthocyanins is the bilberry.
• Bilberries reduce the expression of inflammatory markers and help quell oxidative stress.
• Bilberries are available fresh, dried, frozen, freeze-dried, and in liquid and powdered form.
• Bilberry has long been used to improve night vision.
• Supplementation with 240 mg of bilberry extract over 12 weeks reduced levels of ocular fatigue caused by screen use in 109 healthy subjects
• Incorporate bilberries into smoothies, oatmeal, and salads.

Plums 

• Plums, and their dried counterpart, prunes, contain phenol compounds like neochlorogenic and chlorogenic acid.
• Neochlorogenic acid may inhibit inflammation in the brain.
• Chlorogenic acid has antioxidant activity and can cross the blood-brain barrier to exert its neuroprotective effects on the brain.
• Plum extract has the highest antioxidant compacity of all the stone fruits.
• The skin of a fresh plum has the highest levels of phenolic compounds and the highest antioxidant capacity of the fruit
• Ripe plums will yield to gentle pressure with touch, are slightly soft at their tip, and rich in a deep purplish hue. If plums need ripening, keep them at room temperature, where they will ripen quickly. Once they are ripe, store them in the refrigerator for a few more days.

Purple grapes and raisins, figs, boysenberries, and marionberries are other blue-purple fruits that can support brain health.

Blue-purple Vegetables

Purple kale 

• Purple-stem Chinese kale may contain more health-promoting compounds than other varieties, including higher levels of phenolic acids and flavonoids compared to green-stem kale, and purple kale contains anthocyanin pigments, giving it its rich color.
• Kale thrives during cooler seasons, and it can grow wild, especially in countries along the Mediterranean Sea. The flavor of kale varies from bitter or peppery to plain and even slightly sweet. While the most common leaf color of kale is green, it can vary and be lavender to dark purple, and green-leaf kale may also have purple stems and veins.

Purple potatoes

• Purple potatoes are a good source of antioxidant nutrients like vitamin C and anthocyanins.
• Potatoes as a whole food contain various antioxidant nutrients, including phenols and flavonoids, which can benefit brain health.
• Potatoes are rich in vitamin B6, which plays a role in brain cell and nervous system activity, where it is involved in the production of neurotransmitters like serotonin and dopamine.
• The high levels of anthocyanins in purple potatoes reduce their glycemic impact, potentially due to the inhibition of intestinal α-glucosidase.

Eggplant

• Delphinidin is the purple-colored plant pigment in the skin of purple eggplant that exhibits neuroprotective and antioxidant effects and may prevent memory loss.
• Supplementation with delphinidin may reduce levels of phosphorylated GSK-3β involved with the pathogenesis of Alzheimer’s disease.
• Eggplant is also rich in fiber, minerals, vitamin C, thiamin, niacin, B6, B12, A, E, D, and K
• Try baking eggplant, sauteing it, or stuffing it with other brightly colored vegetables.

Black and purple carrots

• Black and purple carrots are of European origin and are rich in brightly-colored polyphenolic compounds.
• In comparison to the orange carrot, black and purple carrots contain five different anthocyanins in addition to carotenoid pigment.
• Black carrots are 14 times higher in antioxidant capacity than orange carrots.
• Carrots are high in prebiotic fiber and promote healthy diversity in the gut microbiota. A healthy gut microbiota supports cognitive function and prevents neural inflammation.
• Choose black and purple carrot varieties at the farmers market or from community-supported agriculture (CSA) to reap the highest nutrient content.

If you plan to incorporate more colorful, plant-based, whole foods into your daily eating or have food allergies or questions about which foods can best support your health goals, talk to your doctor, nutritionist, dietician, or another member of your healthcare team for personal options based on your circumstances.