An expert committee in USA reviewed evidence regarding use of multi-vitamins commonly used by people in general. They found no proof either way, i.e. there found no support for or against these daily multi vitamin tablets.

So the practice of routinely supplementing with multi-vitamins is not based on sound scientific principles. Although millions of smart & educated folks worldwide adhere to this routine, it is important to note there is no documented unequivocal benefit. A balanced diet provides necessary vitamins in good measure. So what I personally and professionally follow is that if one is not eating healthy or has blood tests showing nutritional or vitamin deficiencies, then it may make sense to utilize these pills.

For example, a city-dwelling single person, working long hours and subsisting mostly on junk/restaurant food, would likely need a multi vitamin pill daily. Another situation is where a blood test for Vitamin B-12 is low, then certainly a Vitamin B-12 containing tablet is warranted. 

This analogy could well be applied to many other such nutrients including calcium,vitamin D, fish oil and magnesium. The powerful pharmaceutical lobby can some times create an artificial sense of medical need compelling the naïve public to purchase ‘nutraceuticals’ for life. Well-read people may believe the news feed planted by wealthy pharma giants who aggressively market such products.  And because these are categorized as nutritional supplements and nonprescription medications, they do not undergo rigorous testing in hundreds of thousands of people before they are permitted to enter the medical market, nor do they have to abide by stringent manufacturing norms. 

This multi-billion dollar industry propagates unsubstantiated concepts of Wellness, through mind-boggling financial deals with celebrities (like Amitabh Bachchan & Sania Mirza plugging Nutricharge, for example) to induce laity towards daily consumption of these products that are completely unnecessary. Amway & Abbott are couple more such towering multi-national companies luring naïve public to purchase unwarranted pills with ostensible health benefits. (Think Farhan Akhtar advocating Nutrilite supplements on TV advertisements). Closer home, Patanjali has captivated the minds of our populous nation, with many more millions of Indian origin abroad gravitating to it's products associating it's purported natural ingredients with Indian culture and glorious vedic past.