Vitamin C helps cure common cold?

Vitamin C helps cure common cold?

Be it building your immunity or fighting the winter chill, the first thing that comes to mind is good old vitamin C – orange juice, lemon or amla juice or failing all, tablets.

Generally, there has been a strong belief that vitamin C protects against colds and diseases. Two-time Nobel Laureate Dr Linus Pauling claimed in the 1970s that the deficiency of vitamin C is the main cause for heart disease and many other degenerative diseases that can shorten life expectancy.

He advocated 5-10 grams (5,000-10,000 mg) of vitamin C per day. The daily recommended intake (DRI) continues to be 40-60 mg a day for the normal population. Cigarette smokers are recommended to consume 80-100 mg a day.

This advocacy led thousands consuming large doses of vitamin C. Its easy availability in pill form and the publication of books recommending it as a "nutraceutical" treatment to prevent and cure colds, cancer and the belief that it is safe and non-toxic, all contributed to its wonder vitamin status.

But do higher doses really offer protection and how much is safe needs to be evaluated?

Vitamin C with antioxidant benefits helps maintain the connective tissue protein collagen, boost immune function, protect against infection, and facilitates iron absorption.

When people dose themselves with supplements, they leave the realm of nutrition and enter that of pharmacology. Like drugs, large doses of nutrients can have medicinal effects on the body and can present serious side effects as well.

The theory that vitamin C prevents or cures cold or cancer, however, has not been supported by research since Pauling suggested it.

Claims that a daily intake of 1000 mg or more of vitamin C will protect against, or cure, the common cold have never been substantiated; while taking supplements may lead to lessening of symptoms and their duration, it cannot actually prevent people from catching a cold. And be careful, regular consumption of anything over 1-2 grams of vitamin C daily can cause serious side effects. These include stomach inflammation, diarrhoea, gastro-intestinal discomfort, abdominal cramps, excessive gas and lower absorption of vitamin B12.

Other hazards of excess vitamin C include altering insulin response to carbohydrate in people with otherwise normal glucose tolerances, formation of kidney stones, alteration of acid-base balance, interference with the action of vitamin E.

The body is totally saturated at a vitamin C intake of 150 mg a day and the excess doses escape the body in stool or urine.

Large amounts of vitamin C excreted in the urine can alter the results of urinary glucose tests used to detect diabetes, giving a false positive result in some instances and a false negative result in others.

Vitamin C in amounts over 250 mg can produce false negative results on tests for occult blood in the stools, masking the presence of potentially dangerous medical conditions like colon cancer. Vitamin C supplements in any dosage may be dangerous for people with an overload of iron in the blood because vitamin C increases iron absorption from the intestine and releases iron from the storage.

In addition, several instances of interference with medical regimens are also known.

Vitamin C also interferes with the effectiveness of amphetamines, blood thinning drugs, and tricyclic antidepressants. People taking medications to prevent blood clotting may unwittingly undo the effect if they have massive doses of vitamin C. Therefore, people must tell their doctors before undergoing any diagnostic laboratory tests. They should also avoid abruptly quitting daily supplementation of 500 mg or more, as it may cause short term scurvy like symptoms and temporarily lowered resistance to infections.

Individuals prone to gout or kidney stones or pregnant women or those on medication should supplement with vitamin C under supervision. Also, supplements are no match to natural sources along with a balanced diet.

The published research on large doses of vitamin C reveals few instances in which consuming more than 100-300 mgs/ day is beneficial.

Adults may not be taking major risks if they dose themselves with a gram a day, but doses approaching 10 grams can be expected to be unsafe. 

Chewable vitamin C can erode dental enamel, may interfere with copper metabolism and increase the risk for gout in individuals who are generally susceptible.

Ample vitamin C is obtained from foods such as amla, citrus fruits, grapefruit, strawberries, guavas, kiwis, black currants, peppers, chillies, broccoli, etc. and it is generally safe.

A glass of orange juice or a medium-sized guava alone gives nearly 125 mg of vitamin C. Considerable amounts of vitamin C are lost during processing, cooking.

So the next time you think of casually consuming vitamin C, remember, too much of good thing is bad.

Source: Ishi Khosla/Indian Express