New findings from the Iowa Women’s Health Study suggest that supplement use in post-menopausal women is linked to increased mortality. Jack blogged about this research yesterday, and I want to also mention it here since I’ve had quite a few questions about it.
As Jack noted, the research on supplements and mortality is very conflicting and it would be a mistake to draw firm conclusions from this study alone. Some of the findings are not supported by other research. That doesn’t make them wrong—it just means that they are not the final word on the subject. This is also an epidemiological study, and while it’s a very good and highly respected one, it still doesn’t provide evidence about cause and effect.
Finally, this study looked at types of supplements taken, but didn’t provide much information on amounts. The findings do suggest that taking huge doses of iron may be harmful. For people who have iron-deficiency anemia, big doses can be necessary, but they should always be taken under a doctor’s supervision and for only as long as needed to reverse the deficiency.
Some may want to use this study to suggest that vegans shouldn’t take supplements. It’s tempting to believe that a diet based on a variety of whole plant foods plus an occasional B12 supplement will automatically meet all nutrient needs.
But vegan diets always need to be supplemented with B12 on a regular basis (not “occasionally”) and often with vitamin D. If you don’t use iodized salt you should take a supplement of iodine. I recommend a DHA supplement as well, although the research on benefits remain conflicting.
If your diet falls short on other nutrients, like calcium, iron or zinc, you can almost always tweak your food choices and cooking style to bring levels back up; supplements shouldn’t be necessary for these nutrients for most vegans, but for some, they may help. It can be difficult for women on low-calorie diets to meet needs for all nutrients; it’s also a challenge for vegans who shun higher-fat foods like nuts and seeds.
The research suggests that there are few benefits to taking supplements for those who are already meeting nutrient needs. But, there is no reason to think that using low dose supplements to make up shortfalls in nutrient intake is harmful.