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Short Summary
Main recommendation: Get vitamin C mainly from whole foods such as berries, citrus fruits, and green vegetables, and keep supplemental intake moderate, generally around 100 milligrams, with a stated ceiling of 500 milligrams per day and an overall limit below 5000 milligrams. Dr. Ahmet Ergin, an endocrinologist, says vitamin C supports growth and repair, collagen formation, immune response, and antioxidant activity, and may help with insulin resistance. He also warns that excess intake above 500 milligrams can cause false glucose readings and other problems.
Key Points
- Vitamin C is linked to collagen formation, immune response, antioxidant activity, and insulin resistance, according to the speaker.
- Taking vitamin C alone may shorten a cold by a few days, for example from about 7 days to about 5, though studies show it does little to prevent colds.
- Cold-related stress raises cortisol and increases the body's need for antioxidants, which the speaker presents as a reason vitamin C may help during illness.
- People who drink alcohol, smoke, or take painkillers, antidepressants, anticoagulants, contraceptives, or steroids may have lower vitamin C levels, according to the speaker.
- Excess vitamin C, especially above 2000 milligrams, can become pro-oxidant and cause oxidative damage.
- Doses above 500 milligrams a day can cause falsely high readings on glucose sensors, which may lead to undertreatment of low blood sugar.
Details Worth Noting
- Concrete instructions: Prefer food sources such as berries, citrus fruits, asparagus, avocados, beets, black currants, broccoli, Brussels sprouts, melon, chard, legumes, grapefruit, kale, lemons, mangoes, mustard leaves, oranges, papayas, peas, peppers, persimmons, pineapple, radishes, spinach, strawberries, tomatoes, and turnip greens.
- Concrete instructions: If you take a supplement, aim for about 100 milligrams, do not exceed 500 milligrams a day, and keep total intake below 5000 milligrams a day.
- Concrete instructions: If you take aspirin, use a low vitamin C dose or get it from food rather than a supplement to reduce stomach irritation, ulcers, or reflux.
- Concrete instructions: Avoid chewable vitamin C because it can damage tooth enamel and gum line.
- Concrete instructions: Pregnant people should avoid excess vitamin C, which the speaker says may cause dependence and scurvy-like problems in the baby.
- Freshly squeezed orange is mentioned as acceptable, but the speaker warns that orange juice can strongly affect people with diabetes and advises against processed orange juice.
- Esterified vitamin C is described as possibly slightly better than other forms, according to the speaker.
Bottom Line
Dr. Ergin says vitamin C is useful mainly through food and moderate supplementation, but high doses can distort glucose monitoring and cause harm, so he advises keeping dosing well below the stated limits.
