Vitamin deficiencies due to diet, disease, or genetics have dire consequences. Severe vitamin A deficiency in infancy and childhood may cause permanent blindness. Vitamin B12 deficiency causes anemia and nerve damage that may be irreversible. Folic acid deficiency in pregnant women can cause birth defects. Vitamin C deficiency causes scurvy and vitamin D deficiency leads to rickets, just to name a few examples. Results from studies with individuals, who do not suffer from known vitamin deficiencies, have been mixed. Recent large placebo-controlled studies have found no significant differences in heart disease or age-related cognitive decline between people, who supplement with a multivitamin or specific vitamins and those, who don’t. But even good placebo-controlled trials have short-comings. They may not be long enough and the use of participants that don’t represent the rest of the population may impact the results. According to the National Institutes of Health, there is presently not sufficient evidence to recommend for or against supplementation with multivitamins/minerals to prevent chronic diseases. However, there are new studies on multivitamins that looked at outcomes other than chronic diseases.
Multivitamins and weight loss
Researchers looked at the effect of supplementing with a multivitamin/minerals or calcium on obesity, because obese individuals often have low blood concentration or low bioavailability of vitamins and minerals. They measured energy expenditure and blood lipid profiles in 96 obese Chinese women, aged 18-55 years old. This was a randomized, placebo-controlled trial that lasted 26 weeks. The women were divided into three groups, who either received a multivitamin and mineral supplement, 162 mg of calcium, or a placebo in the control group. They measured body mass index, energy expenditure, respiratory quotient, and cholesterol and triglyceride levels before and at the end of the study. At the end of the study, the women, who took the multivitamin/mineral supplement had significantly lower body weight, body mass index, total cholesterol, and lower LDL, the bad cholesterol. These women also had greater resting energy expenditure and higher levels of HDL, the good cholesterol. The calcium group only had improved cholesterol levels compared to the placebo group. The researchers conclude that the weight loss in the multivitamin group may have occurred, because of the increase in resting energy expenditure and fat oxidation.
Multivitamins and mood
In a randomized, double-blind, placebo-controlled study, researchers looked at the effect of vitamin supplementation on mood, mental health, and vigor in 215 men, aged 30 to 55. The participants underwent at the start and at the end of the 33 day-long study, mood, stress, physical and mental tests and also had to answer questionnaires. At the beginning of the study, there were no differences between the control group and the group assigned to the multivitamin group. At the end of the study, the group that took the multivitamin improved in mood, stress level, and vigor, had reduced “mental fatigue” and performed better at cognitive tasks.
If you eat a varied and healthy diet, you may not need to supplement with a multivitamin/mineral; supplementation will just produce “expensive urine”. But many people are not always able to eat a healthy balanced diet may or pursue a healthy lifestyle. Being sick and medications may also interfere with nutrient absorption. People over 50 may not absorb nutrients as well as younger people and may gradually develop a vitamin deficiency. In some cases, as with vitamin B12, vitamin supplements may be better absorbed than when B12 is contained in food. Although good nutrition can provide all the essential vitamins and minerals, supplementation with multivitamins and minerals insures that no deficiency develops and may even help you lose weight and improve your mood.
Li, Y. et al. Effects of multivitamin and mineral supplementation on adiposity, energy expenditure and lipid profiles in obese Chinese women. Int. J. Obesity (2010) 34: 1070