Q: Is there any medical/scientific research that shows a negative impact that vitamin C can have on the liver?
— Loren B., Burlingame, Calif.
A: I am not aware of any liver toxicity from vitamin C itself when taken in reasonable doses. What you may be referring to is the danger of vitamin C in people with a hereditary condition called hemochromatosis, which causes the body to absorb too much iron from food. The excess iron is stored in organs, especially the liver, heart, and pancreas.
Vitamin C complicates this condition because it greatly enhances the absorption of iron from the gut.
In people with hemochromatosis, iron levels in the liver and other tissues are already extremely high. These high iron levels result in severe damage to the liver and can lead to liver failure and/or liver cancer.
People with hemochromatosis should avoid vitamin C supplements. I also recommend that people take their vitamin C between meals to avoid excess iron absorption.
One recent study using mice found that very high doses of vitamin C, when combined with severe stress, damaged the liver of the animals. However, the dose of vitamin C used on the mice would be equal to 35 grams in humans — a massive dose. Lower doses in this study caused no damage.
In general, I suggest buffered vitamin C — it is easier on the stomach, does not induce acidosis, and is better absorbed. Interestingly, a number of new studies show that vitamin C protects the liver against damage by a number of toxins, such as alcohol.
Q: I recently heard that astaxanthin is supposed to be the new superantioxidant of the future. Do you think it should be part of our daily supplements? If so, how much should we take?
— Nancy O., Nipomo, Calif.
A: Astaxanthin is one of the hundreds of carotenoids found in plants. Unlike beta-carotene, it is not converted into vitamin A in the body. Recent studies have found a number of health-promoting effects from astaxanthin. For example, it can correct age-related immune suppression in the elderly — a major cause of death from flu and a cause of pneumonia.
It was also found to offer powerful protection for the brain, especially against Alzheimer’s disease, and protects the heart by improving blood pressure, strengthening the heart muscle, and protecting against free radicals and lipid peroxidation.
While astaxanthin improves all aspects of immune function, most important is that it improves natural killer cell function — which is essential for protecting against cancer and infections.
Even though it improves immune function, studies have shown that it does not worsen autoimmune diseases in animal studies. Most studies suggest that the greatest benefits can be had from taking the supplement for a long time.
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