Physicians are frequently confronted with patients complaining of fatigue, tiredness and low energy levels. In the absence of underlying disease, these symptoms could be caused by a lack of vitamins and minerals. Certain risk groups like the elderly and pregnant women are well-recognized. Our aim was, therefore, to find out if other, less well-established groups might also be at risk. Thus, the objectives of this review are: to describe the inter-relationship between micronutrients, energy metabolism and well-being; identify risk groups for inadequate micronutrient intake; and explore the role of micronutrient supplementation in these groups. A review of the literature identified an important group at risk of inadequate micronutrient intake: young adults, often women, with a demanding lifestyle who are physically active and whose dietary behaviour is characterized by poor choices and/or regular dieting. Micronutrient supplementation can alleviate deficiencies, but supplements must be taken for an adequate period of time.