Anthocyanins are phenolic compounds of plant origin, composed of an anthocyanidin backbone with sugar and acyl conjugates. They are mainly purple-colored but provide various colors, such as red, pink, or blue. Anthocyanins have been linked to key roles in plant survival by helping plants protect against many abiotic and biotic stresses. Don’t miss out on this game-changing nutrient – read on and unlock the power of purple today!
Table of Contents
What are the sources of anthocyanins?
"Anthocyanins responsible for the colors, red, purple, and blue, are in fruits and vegetables."
Anthocyanins are found in:
- fruits (berries, cherries, grapes, pomegranates, plums, blackcurrants)
- vegetables (red onions, red radishes, black beans, eggplants, purple corn, purple carrots, red cabbages, and purple sweet potatoes)
- colored varieties of cereals
However, anthocyanin contents of these plants vary across species and cultivars along with environmental factors as anthocyanins are highly unstable and easily degraded by enzymes, light, temperature, pH, and oxygen concentration. Moreover, the bioavailability of flavonoids is low with only 1–2% of intact anthocyanins found after oral ingestion.
Health benefits and therapeutic potential
In the last 5 years, there have been significant advances in developing the therapeutic potential of anthocyanins in chronic human diseases. Their health benefits in humans include improvements in gut microbiota, oxidative stress, and inflammation, modulation of neuropeptides such as insulin-like growth factor-1; reduced cognitive decline; protection of organs (lungs, gastrointestinal tract, and kidneys), as well as the cardiovascular system, improvements in bone health and obesity; and regulation of glucose and lipid metabolism.
Mechanism of Action
Gut Microbiota
Anthocyanins can be absorbed in the stomach by specific transporters such as sodium-dependent glucose co-transporter 1, metabolized by the gut microbiota (the microorganisms in the gastrointestinal tract) in the colon, and modified by metabolic enzymes in liver cells followed by accumulation in tissues.
Metabolites could independently function in chronic disease states; for example, a major metabolite, protocatechuic acid, has demonstrated antioxidant, anti-inflammatory and neuroprotective properties. Regulation of the gut microbiota by anthocyanins may reduce kidney injury to treat pre-existing chronic kidney disease.
Anthocyanins also act as prebiotics to modify the microbiota, in particular enhancing Lactobacillus spp. and Bifidobacterium spp., potentially leading to cardioprotective and neuroprotective responses and decreased bone loss in the aging population.
Oxidative stress
Oxidative stress is a key activator of disease onset and progression. Anthocyanins and their metabolites may improve mitochondrial function and decrease inflammation by decreasing reactive oxygen species (ROS) concentrations.
Further, some anthocyanins may form an additional transport chain in damaged mitochondria as electron acceptors to reduce cytochrome C and increase ATP production. Anthocyanins may be involved in epigenetic mechanisms to reverse aberrant methylation and oxidative stress without changing the underlying gene sequences. Potential therapeutic targets include diabetes, cancer, and Alzheimer’s disease.
Inflammation
Low-grade chronic inflammation underlies many chronic systemic diseases, especially age-related decline and metabolic disorders. Anthocyanins regulate pro-inflammatory markers in both healthy and chronic disease states. Together with their metabolites, they decrease neuroinflammation. The major reason for decreased neurotoxicity could be the changes in gut microbiota.
IGF-1
The neuropeptide IGF-1 has important roles in the development and maturation of the brain. The study of the interactions of IGF-1 and anthocyanins is relatively recent but it is providing a potential mechanism for their therapeutic benefits in chronic neurodegenerative, cardiovascular, and metabolic diseases.
Therapeutic activity in chronic diseases (clinical studies)
Delaying cognitive decline
Older adults with mild cognitive impairment at risk of dementia improved working memory after a 16-week intervention with blueberries with a daily dose of 269 mg cyanidin 3-glucoside (C3G, one of the most common natural anthocyanins) equivalents.
Modulating neurological diseases
Consumption of strawberries has been associated with a decreased risk of Alzheimer’s dementia. Patients with Parkinson’s disease scored lower on anxiety and depression scores after administration of blackcurrant concentrate (300 mg twice daily for 4 weeks).Protecting organs
In patients with non-alcoholic fatty liver disease, intervention for 12 weeks with a bilberry and blackcurrant mixture containing 320 mg anthocyanins improved insulin resistance, indicators of liver injury.
Decreased blood pressures in mildly hypertensive patients were reported after giving Queen Garnet plum juice containing 255 mg C3G equivalents for 12 weeks. It also reduced the postprandial effects of a high-fat high-energy meal on vascular endothelial function and inflammatory responses in older humans.
Maintaining glucose levels and decreasing obesity
In clinical trials of diabetes, anthocyanins reduced blood glucose and HbA1c concentrations and improved insulin secretion and resistance.
Treatment with anthocyanins (320 mg/day for 12 weeks) in patients with untreated fasting hyperglycemia decreased blood glucose and C-peptide concentrations and increased blood IGFBP-4 fragments, suggesting that anthocyanins can improve glucose homeostasis by activating the IGF system.
Anthocyanin supplementation of 300 mg/day or less for 4 weeks was sufficient to lower body mass index and body weight. A dose of approximately 200 mg anthocyanin /day for 4 weeks decreased body weight by 0.6 kg in healthy individuals together with increased blood adiponectin and reduced blood leptin concentrations.
Protection against cancer
Anthocyanins can help in preventing DNA damage from oxidative stress in the initial stage of tumor formation.
Moderating aging
Anthocyanins have shown beneficial effects on glaucoma when administered at 50 mg/day for up to 2 years.
Anthocyanins from pomegranate have shown anti-aging effects on the skin with improved skin permeation in aged humans.
Conclusion
Anthocyanins mediate a range of pharmacological effects, most likely due to changing the gut microbiota, decreasing oxidative stress, inflammation, and neuroinflammation, and increasing the neuropeptide.
Original article:
- Panchal SK, John OD, Mathai ML, Brown L. Anthocyanins in Chronic Diseases: The Power of Purple. Nutrients. 2022 doi: 10.3390/nu14102161.
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