Vitamins give you energy – but will taking extra vitamins make you more energetic?
We need the B group vitamins – including thiamin, riboflavin, niacin, biotin and pantothenic acid – to produce energy in the cells of our bodies. But it does not follow that if you have more B vitamins you'll feel more energetic. If you're not eating enough of these vitamins it would help, but you're unlikely to have a deficiency if you eat a normal healthy diet.
On their website, Bayer, the manufacturer of Berocca, refers to a trial it sponsored with people who did have a diet likely to be lacking in vitamins and minerals. Over 4 weeks, the people taking Berocca reported reduced levels of anxiety and stress. There's a good reason for that: one of the first signs of small vitamin and mineral deficiencies is likely to be your psychological status. There are no scientific studies cited to support claims about increased energy.
The bottom line: Mostly myth
If taking B vitamins makes you feel better, you may need to take a look at your diet as you're likely to be deficient in other vitamins as well. Eating a wide variety of good food and getting some exercise is likely to do more for your energy levels than popping a pill.