Why shouldn't anthocyanins be taken for a long period?

Dec 08, 2025 Source: Cainiu Health

Dr. Huang Yuhong

Introduction

Anthocyanins should not be consumed in excess over a long period, as this may lead to gastrointestinal dysfunction, impaired nutrient absorption, increased metabolic burden on the liver and kidneys, interference with drug efficacy, and worsened allergic reactions. Intake should follow the principle of moderation. If persistent diarrhea, rash, or other physical discomfort occurs after prolonged consumption, medical attention is recommended. Anthocyanins are highly acidic and may cause long-term irritation.

Anthocyanins should not be consumed in excess over a long period, as this may lead to gastrointestinal dysfunction, impaired nutrient absorption, increased metabolic burden on the liver and kidneys, interference with medication efficacy, and worsening of allergic reactions. Intake should follow the principle of moderation. If persistent diarrhea, rash, or other physical discomfort occurs after prolonged consumption, medical advice should be sought promptly.

1. Gastrointestinal Dysfunction: Anthocyanins are highly acidic. Long-term stimulation of the gastrointestinal mucosa can cause excessive gastric acid secretion, leading to symptoms such as acid reflux, stomach pain, and diarrhea—particularly noticeable in individuals with sensitive digestive systems.

2. Impaired Nutrient Absorption: Excessive anthocyanins may bind with minerals such as calcium, iron, and zinc, forming complexes that are difficult to absorb. Over time, this can reduce the absorption rate of dietary minerals and increase the risk of nutritional deficiencies.

3. Increased Metabolic Burden on Liver and Kidneys: Anthocyanins are metabolized and excreted through the liver and kidneys. Long-term, high-dose intake may exceed the metabolic capacity of these organs, increasing their workload and potentially impairing normal liver and kidney function over time.

4. Interference with Medication: Due to their antioxidant activity, long-term consumption of anthocyanins may interact with medications such as antihypertensives, antidiabetics, or anticoagulants, affecting drug efficacy or increasing the risk of adverse effects.

5. Worsening of Allergic Reactions: Some individuals are sensitive to anthocyanins. While small amounts may not cause immediate issues, long-term intake can lead to cumulative sensitization, triggering or exacerbating allergic symptoms such as skin itching and rashes.

It is recommended to obtain anthocyanins primarily from natural food sources such as fresh fruits and vegetables—including blueberries, purple sweet potatoes, and grapes—rather than relying on supplements over extended periods. Daily intake should remain within a reasonable range, and additional supplementation is unnecessary when following a balanced diet.

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Can you eat the purple skin of pistachios?

The purple skin of pistachios is edible and is usually due to varietal characteristics or natural pigments; however, avoid consumption if signs of spoilage are present. The skin of certain pistachio varieties is naturally purple, or may turn purple due to the accumulation of natural anthocyanins during growth. This type of purple skin has no off-odor, feels dry in texture, and does not compromise food safety when consumed with the kernel. It may even contain beneficial natural compounds.

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What to eat for good eye health

Foods that are good for the eyes generally include blueberries, carrots, spinach, egg yolks, and salmon. Blueberries: Rich in anthocyanins, blueberries help protect retinal photoreceptor cells, reduce light-induced eye damage, promote ocular blood circulation, and relieve eye fatigue. They are especially suitable for people who use their eyes extensively. Blueberries can be eaten raw or paired with yogurt.

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What should I do if my eyes are becoming a bit nearsighted?

In general, mild myopia may be caused by excessive eye strain, genetic factors, visual fatigue, dry eye syndrome, congenital cataracts, or other reasons. It is recommended to seek medical attention promptly, identify the underlying cause, and then improve the condition through appropriate methods under a doctor's guidance. In daily life, consume more foods rich in vitamin A and anthocyanins, such as carrots and blueberries, and ensure eight hours of sleep per day to allow the eyes to rest fully.