Despite the many claims to the contrary, there is relatively little scientific evidence that proves any substantial and lasting benefits from taking vitamin supplements.
The supplement industry is worth billions of dollars, but a new study shows that when it comes to lowering cancer risk, nutrients from food and not supplements have a much bigger impact.
In fact, researchers from Tufts University who conducted the study found that excess calcium intake (over 1,000 milligrams a day) through supplements increased the risk of cancer death.
The results of the study were published in the journal Annals of Internal Medicine.
“As potential benefits and harms of supplement use continue to be studied, some studies have found associations between excess nutrient intake and adverse outcomes, including increased risk of certain cancers,” said Fang Fang Zhang, the senior author for the study. “It is important to understand the role that the nutrient and its source might play in health outcomes, particularly if the effect might not be beneficial.”
The researchers reviewed and analyzed a nationally representative sample of data from 27,000 US adults aged 20 or older.
The data came from six two-year cycles of the National Health and Nutrition Examination Survey where participants were asked to recall past dietary information.
Nutrients from food were calculated using the dietary recalls, and the researchers turned to product information for supplements to calculate the nutrients per dose depending on how often each supplement was taken.
The researchers analyzed the data to compare cancer-lowering risks of nutrients from food versus nutrients received from supplement intake.
Getting enough vitamin K, magnesium, vitamin A and zinc correlated with a lower risk of death and cardiovascular disease, whereas excess calcium from supplements increased the risk of death from cancer.
The lower risk of death and cancer were limited to nutrients from food and not supplements.
Dietary supplements had no impact on lowering the risk of death even in participants who reported low nutrient intake.
There are some limitations to the study as much of the data relied on self-reported dietary recalls, but the results indicate that there is very little evidence to suggest that nutrients from supplements are beneficial to health and nutrition.
“Our results support the idea that, while supplement use contributes to an increased level of total nutrient intake, there are beneficial associations with nutrients from foods that aren’t seen with supplements,” said Zhang. “This study also confirms the importance of identifying the nutrient source when evaluating mortality outcomes.”