Many people who work in front of a computer screen all day and don’t get enough relief experience physical deterioration, prompting them to take vitamin supplements to replenish nutrients their daily diet may not supply sufficiently. But be warned: overdosing vitamin and other supplements can adversely affect body functions, as follows:
Vitamin C is essential for building immunity, providing antioxidants, preventing colds and just giving the skin a healthy glow. On average adults need 65-90 milligrams of vitamin C daily – but not more than 2000 milligrams. When we take vitamin C, our body converts it into oxalic acid and oxalate. If we take too much vitamin C, our body might not excrete all the oxalate in the urine. It then accumulates in the kidneys causing kidney stones to develop.
As such, those with a history of gallstones should be especially cautious about overdosing vitamin C supplements. They should opt instead for vitamin C-rich fruits which will give them enough to meet their body’s needs. One orange provides about 70 milligrams of vitamin C, for example. Note that our bodies have a saturation point for vitamin C absorption, so we should divide our vitamin C intake into different times of the day, taking no more than 1000 milligrams each time to allow our body to absorb it properly.
Vitamin B12 nourishes the nervous system, metabolism, and red blood cell formation. Insufficient vitamin B12 causes numbness in hands and feet, decreased brain function, and possibly anemia.
Adults require 2.4 micrograms of vitamin B12 daily. If we take more, our body will simply excrete it, so no harm is done. Foods high in vitamin B12 include tuna, salmon, and meat. But note that taking vitamin B12 along with certain medications, including Metformin (an antidiabetic drug) and acid secretion inhibitors, reduces B12 absorption efficiency.
Many people, especially the elderly and pregnant women, take calcium supplements, as calcium helps build bone mass and maintain good bone and teeth condition. Calcium is best ingested in the form of food and in conjunction with exercise. Adults aged 19-50 need 1,000 milligrams of calcium daily. The elderly need more like 1,200 milligrams. Foods high in calcium include yogurt, mozzarella cheese, sardines, and milk, among others. If calcium is taken in the form of a supplement, it should be under the supervision of a doctor. Taking too much can cause constipation and increase the risk of developing gallstones and cardiovascular disease.
Older women taking hormone modulators to increase estrogen levels to balance the body and slow the onset of menopause symptoms such as hot flashes, mood swings and osteoporosis, should get advice from a doctor. Such hormone modulations may have side effects, ranging from general conditions such as headaches, indigestion, emotional instability and irregular menstruation, to severe conditions such as heart disease, thrombosis, and breast cancer.
Zinc helps regulate various processes in the body at the cellular level, including enzyme efficiency and tissue repair. Generally speaking, women need 8 milligrams of zinc daily while men need 11 milligrams. Foods high in zinc include oysters, beef, pork chops, and others. However, too much zinc causes diarrhea, nausea and vomiting. It also diminishes the effectiveness of penicillamine and antibiotic type drugs.
Every person's physical condition is different, so always consult your registered pharmacist or doctor for advice on the vitamin and supplement intake that is most appropriate for you.
National Institute of Health
Faculty of Medicine Ramathibodi Hospital, Mahidol University
Public & Consumer Affairs Division, Food and Drug Administration
Drug Information Center, Faculty of Pharmacy Mahidol University