However, they did find adequate intakes of vitamins A and K, magnesium, zinc and copper could lower the risk of death and diseases like cardiovascular disease and cancer. But this was only the case when the nutrients came from food, not supplements.
Furthermore, researchers said taking 1,000 or more milligrams of calcium a day was linked with an increased risk of death from cancer. Also, those who took vitamin D supplements, but had no vitamin D deficiency, may have a higher risk of death from all causes.
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"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," co-author Fang Zhang said in a statement. "This study also confirms the importance of identifying the nutrient source when evaluating mortality outcomes."
The authors did note some limitations. They acknowledged they collected data on supplements used only during the previous 30 days. They also said the dosage of supplements used was self-reported.
However, they said they believed their findings are strong and hope to continue their investigations.
“It is important,” Zhang said, “to understand the role that the nutrient and its source might play in health outcomes, particularly if the effect might not be beneficial.”
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