Anthocyanidins are natural pigments found in nature and are commonly used as natural colorants in food processing or as health supplement materials. Among various natural colorants, two major categories are frequently used: one is fat-soluble carotenoids, with lutein and zeaxanthin being classic representatives, and the other is water-soluble pigments, namely anthocyanins. This article will delve into the relationship between anthocyanidins and proanthocyanidins, the benefits of anthocyanidins for the human body, and foods that contain anthocyanidins. Let’s explore each of these aspects:
What is Anthocyanidins?
Anthocyanidins are a group of flavonoid polyphenolic compounds found in plants. They can be classified into two main categories based on whether they undergo modifications:
- Anthocyanidins: These are the basic, unmodified forms of anthocyanins. They are flavonoid compounds responsible for the vibrant colors found in many fruits, vegetables, and flowers.
- Anthocyanins: These are the modified forms of anthocyanidins. Anthocyanins are glycosides, meaning they have sugar molecules attached to them. These modified compounds contribute to the diversity of colors in plants.
There are over 1000 identified anthocyanins, and they are often derived from the structural variations of six common anthocyanidins. These anthocyanidins, ranked by their prevalence in nature, are:
- Cyanidin: Gives a red-orange color.
- Delphinidin: Imparts a red hue.
- Pelargonidin: Produces an orange color.
- Peonidin: Adds a red-orange shade.
- Malvidin: Contributes to a blue-red color.
- Petunidin: Generates a red color.
what’s the difference between Anthocyanidins and proanthocyanidins?
Anthocyanins and proanthocyanidins are two types of flavonoid polyphenolic compounds. While their names and structures might appear similar, they do have distinct differences.
Proanthocyanidins are commonly found in two forms: A-type proanthocyanidins and B-type proanthocyanidins.
When exposed to acidic and heated environments, proanthocyanidins can convert into red anthocyanins. In comparison to anthocyanins, proanthocyanidins tend to exhibit a more uniform red color.
In general, the stability of both anthocyanins and proanthocyanidins is influenced by factors such as light, oxygen, pH levels, metal ions, and enzymatic degradation. Different conditions and environments can affect the structure and characteristics of these compounds[1].
Physiological Characteristics of Anthocyanins
After consumption, a portion of anthocyanins can be absorbed by the stomach, while the majority is absorbed through the small intestine. Once absorbed, anthocyanins can reach their peak plasma concentration within approximately 30 minutes to 4 hours (depending on the type of anthocyanin). Subsequently, they can undergo further metabolism in the small intestine, as well as be transported to the liver and kidneys for additional processing. Ultimately, they are excreted from the body through urine.
On the other hand, anthocyanins that cannot be digested or absorbed by the human body enter the large intestine, where they interact with intestinal bacteria or are directly eliminated through feces[2].
Six Benefits of Anthocyanins
Anthocyanins and proanthocyanidins not only provide vibrant colors but also offer several benefits to the human body:
1. Antioxidant Effects
Anthocyanins exert their antioxidant power through two main mechanisms:
– First, they bind to free radical molecules through their structure, reducing the instability of free radicals.
– Second, they modulate gene expression, increasing the activity of endogenous antioxidant enzymes and reducing the generation of endogenous free radicals.
💡 Experiments have shown that consuming strawberries or red wine after a meal is positively correlated with increased serum anthocyanin levels and enhanced antioxidant capacity. Human trials have also demonstrated that consuming 300 grams of strawberries (approximately 9.57 mg of anthocyanins) can boost internal antioxidant capacity[7].
2. Anti-Inflammatory Effects
In addition to inhibiting gene and protein expression in inflammatory pathways, anthocyanins can also reduce the production of inflammatory mediators, such as cytokines or prostaglandins.
💡Human trials have revealed that supplementing with 12 grams of red wine extract (containing 183.8 mg of anthocyanins) can modulate endothelial cell chemokines, leading to the suppression of inflammatory responses in the body[8].
3. Beneficial for Vision
Anthocyanins provide numerous benefits for vision as they can cross the blood-retinal barrier to reach ocular tissues. They offer various advantages for visual health, including:
1. Regenerating Retinal Pigments: Enhancing night vision.
2. Improving Retinal Microcirculation: Increasing blood flow in the retinal microvasculature.
3. Slowing Diabetic Retinopathy Progression: Delaying the advancement of diabetic retinal disorders.
4. Reducing Eye Diseases: Lowering the incidence of conditions like retinitis and cataracts through antioxidant and anti-inflammatory effects.
💡Incorporating 50 mg of anthocyanins sourced from black currants can alleviate eye fatigue after prolonged computer use in healthy adults. Supplementation with 180 mg of elderberry extract (containing 45 mg of anthocyanins) twice daily for four months can help prevent the progression of age-related cataracts. For individuals with normal intraocular pressure glaucoma, supplementation with anthocyanins from blueberries, combined with increased blood circulation due to antioxidant activity, can enhance overall visual function[3].
4. Neuroprotection and Cognitive Enhancement
Anthocyanins possess properties that can inhibit neuroinflammation and regulate neural signal transmission. They can also enhance cerebral blood flow, preventing cognitive decline and slowing neurodegenerative diseases.
💡Supplementing with 200 ml of cherry juice rich in anthocyanins for 12 consecutive weeks can improve language communication fluency, learning capacity, memory, and cognitive function in the elderly with mild to moderate cognitive impairment[9].
💡In another double-blind trial involving participants aged 65 to 80, supplementation with blueberry extract for three months resulted in improved executive function (attention, decision-making, abstract thinking, etc.) and episodic memory (memory related to time, place, or specific events)[10].
5. Promoting Heart Health
Anthocyanins exhibit antioxidant, anti-LDL oxidation, anti-inflammatory, and antiplatelet aggregation properties. These effects contribute to the protective role of anthocyanins in heart health.
💡Healthy adults supplementing with 300-500 ml of anthocyanin-rich grape juice daily for 7-28 days were found to inhibit platelet aggregation[11].
💡In individuals with high cholesterol levels, daily consumption of 320 mg of anthocyanins for 12 weeks effectively improved vascular dilation, increased HDL (good cholesterol) levels, and reduced triglycerides, LDL, and glycated hemoglobin (HbA1c)[12].
6. Antimicrobial and Antiparasitic Activity
Anthocyanins can disrupt the integrity of bacterial cell walls or cell membranes, affecting the structural integrity of bacteria and reducing their ability to bind to hosts. Additionally, anthocyanins can directly impact the activity of microbial enzymes, thereby interfering with their replication or their ability to form biofilms.
Due to their ability to interfere with and inhibit bacterial growth, anthocyanins might offer some degree of help in urinary tract infections.
💡Currently, the more supported research suggests that A-type proanthocyanidins (PAC) with a dosage of at least 36 mg or more effectively reduce the ability of bacteria to bind to bladder epithelial cells, lowering the risk of urinary tract infections.
Which Foods Contain Anthocyanins
While many vegetables, fruits, and grains contain significant amounts of anthocyanins, the primary sources are edible berries, red wine, and certain vegetables and fruits. The content of anthocyanins can also vary due to different cultivation environments, storage conditions, and quantitative analysis methods[4][5]. Here are some examples of foods with relatively high anthocyanin content:
- Bilberry: 300–698 mg
- Black bean: 24.1–44.5 mg
- Black currant: 130–476 mg
- Blueberry: 61.8–299.6 mg
- Elderberry: 664–1816 mg
- Goji berry: 49.4 mg
- Maqui berry: 137-138 mg
- Red radish: 100–154 mg
- Red cabbage: 322 mg
- Red grape: 30–750 mg
*the anthocyanin content is given per 100 grams of the respective food.
When to Consume Anthocyanins
Anthocyanins are water-soluble nutrients, so their consumption timing generally has minimal impact. However, some studies suggest that pure anthocyanin supplements might not be well absorbed and that a high-fat diet could interfere with the digestion of anthocyanins. Therefore, it’s advisable to take anthocyanin supplements after meals that are not high in fat.
Recommended Intake of Anthocyanins
While most people tolerate anthocyanins well, high doses (160 mg per dose, twice a day) for 1-2 months can lead to gastrointestinal and skin-related side effects in about 4% of individuals. According to human trials, an effective daily dose of anthocyanins is around 50 mg per day[6].
Groups that Benefit from Anthocyanin Supplementation
Various groups can benefit from anthocyanin supplementation based on its effects, including those focusing on eye health (for visual benefits), individuals who frequently eat out (to compensate for a lack of colored fruits and vegetables in their diet), individuals interested in beauty (due to its strong antioxidant properties), and the elderly (for cardiovascular protection and prevention of neurodegenerative conditions).
Are Anthocyanin Complex Formulas More Effective?
For consumers primarily seeking eye health benefits, when selecting supplements, it’s essential to consider not only the dosage of anthocyanins but also to include lutein and zeaxanthin for eye protection. It’s even better if the supplement also contains astaxanthin, which enhances the ciliary muscle’s regulation ability. Combination formulas are often more effective than single ingredients.
While anthocyanins and proanthocyanidins are not essential nutrients, they are significant phytochemicals. Their physiological functions may overlap, particularly in antioxidant, anti-inflammatory, and cardiovascular protection aspects. For eye health, it’s recommended to supplement with anthocyanins, lutein, zeaxanthin, and astaxanthin. If preventing urinary tract infections is the goal, then proanthocyanidins and D-mannose, along with probiotics, can be beneficial.
