As a child, our homemade remedy for a cold was a glass of warm calamansi juice. The calamansi was picked from trees in our garden. I later learned that it was the vitamin C in the juice that supposedly helped boost my immune system, helping me to get better.

The truth is that vitamin C can help reduce the duration of a cold, but it does not really prevent the common cold. This has been seen only in persons involved in high-intensity physical activity in extremely cold climates — not an everyday scenario.

More people also started taking more vitamin C during the (Covid-19) pandemic. While it is not harmful to take if you have Covid, there is also no evidence to suggest that it will prevent or treat the disease.

Vitamin C is also known as ascorbic acid, and helps to protect cells and keep them healthy, maintaining skin, blood vessels, bones and cartilage, and also helps with wound healing. A deficiency in vitamin C is called scurvy, where you can have bleeding of the gums and bruising in the skin.

Good sources of vitamin C include, not only citrus fruits such as oranges and calamansi, but also vegetables like broccoli, potatoes, spinach and tomatoes. Heat destroys ascorbic acid, so cooking can reduce the vitamin C content of food. Steaming or microwaving may lessen these losses. Fortunately, many of the best food sources of vitamin C are usually consumed raw.

The recommended daily dose of vitamin C for Filipinos is about 30-70 mg per day. Consuming five varied servings of fruits and vegetables a day can give around 200 mg, while supplements usually contain 500 mg of vitamin C. Doses of up to 1000 mg a day are generally safe to take, but more than that and you can have stomach pain, bloating and diarrhea.

Intravenous (IV) infusions of vitamin C are also being offered by some practitioners as part of a wellness trend, usually in combination with other vitamins and minerals. Since this infusion is given in liquid form, the body receives more hydration, and this is believed to be the reason people feel better after receiving this treatment, and not the cocktail of vitamins.

The body ordinarily absorbs nutrients slowly with tablets, while vitamin IV therapy allows for rapid absorption of nutrients at higher doses. This is helpful for patients who cannot take or absorb oral supplements properly. But this can lead very quickly to toxic levels in the body, especially in patients with liver and kidney conditions.

There is also a risk of developing kidney stones if you take too much vitamin C. It is water soluble, so whatever the body does not need is filtered by your kidneys and is eliminated in your urine (that is why your urine turns very yellow after taking too much vitamin C). Make sure you drink enough water while taking these supplements, about eight to 10 eight-ounce glasses a day.

Vitamins are substances that cannot be made by the human body so they must be added to the diet in small amounts for the body to function normally. Vitamins (such as A, C and D) should be distinguished from minerals (such as calcium and iron), some of which are also essential micronutrients.

A balanced and healthy diet that incudes vegetables, fruits and protein should be adequate to fulfill the need for these vitamins and minerals. If you are unable to get them in your diet, then you can take a tablet to “supplement” your diet (thus why they are called supplements).

Supplements should always be taken with caution. Some patients argue that these are “just vitamins” and can’t cause any trouble. But they can interact with your medications, depending on the type and timing of when you take them, or can be dangerous in certain medical conditions. Taking an excess of vitamins also won’t make you healthier or prevent a certain disease and can cause more harm than good.

As always, ask your doctor first whether a supplement is right for you before taking them, to lessen the risk of any untoward side effects or interactions, and so that you get the most out of them for your health.