Updated: Jun 27
This question alone may sound a little strange, but our society has become a lot friendlier with dietary supplements and vitamins in the past few years. The truth is, you could not survive on dietary supplements alone.
In fact, “dietary supplements don’t extend life and might actually shorten it.”  Without being implemented into a meal, these dietary supplements only provide specific nutrients, but not enough for the body to sustain itself. In fact, for most people “there’s no need to take dietary supplements” says Fang Zhang, a professor of epidemiology (a branch of medicine dealing with disease and health).  There is also the fact that supplements can be harmful to the body when taken in large quantities, due to their active ingredients. Life-threatening risks can occur if someone is “combining supplements, mixing supplements with medicines, or taking too much of some supplements, especially vitamin A, vitamin D, and iron.” 
Although it is not recommended to replace your meals with supplements, they can improve your health overall when taken properly. In a study done by the National Health and Nutrition Examination Survey, it was shown that “getting enough vitamin A, vitamin K, magnesium, zinc and copper were all associated with a lower risk of dying early.”  However, this is also getting enough, rather than getting too much. To contrast, it was shown that “people who took vitamin D supplements but were not deficient in vitamin D also had a higher risk of dying.”  In moderation, these supplements can provide nutrition to those who do not have enough of a certain vitamin or supplement.
So, it wouldn’t be wise to overdose on dietary supplements, or to use them as meal replacements. Instead, consider pairing these supplements with healthy meals, exercise, and other healthy lifestyle habits. And even before that, it is recommended that you talk to a doctor or a nutritionist to figure out what you need, and what you don’t.
1. Carrol, L. (2019, April 9). Vitamin supplements don't help people live longer, study finds. NBC News.