Whether it's antioxidants, multivitamins, probiotics, or good old Vitamin C, the sad truth is that most supplements and vitamins you see on your supermarket shelves are useless - and could even be dangerous for your health.
But there's one big exception when it comes to women who are thinking about getting pregnant at some stage in their lives - folic acid, which is one of the rare supplements that actually has some really strong scientific backing.
According to a new report from the US Preventive Services Task Force - an independent, volunteer-driven panel of health experts - anyone who is capable of getting pregnant should be taking folic acid supplements daily, even if you're not planning on getting pregnant in the near future.
The report emphasises the fact that most women do not get the recommended daily amount of folate - a type of B vitamin - from their diets alone, which makes the folic acid supplement an important consideration.
The difference between folate and folic acid is that folic acid refers to an oxidised synthetic compound that can be taken in supplements or fortified food, which mimics the effects of naturally occurring folate.
The concern that most women aren't getting enough folate from their diets is that a healthy supply of folate can prevent some of the most common birth defects from occurring - neural tube defects, which can seriously alter the development of the brain, skull, and spine, and lead to disability or death.
"Neural tube defects are among the most common major congenital anomalies in the United States and may lead to a range of disabilities or death," the US Preventive Services Task Force reports.
"Women who have a personal or family history of a pregnancy affected by a neural tube defect are at increased risk of having an affected pregnancy. However, most cases occur in the absence of any personal or family history."
The official recommendation is that anyone who is capable of getting pregnant should be taking a daily supplement that includes 0.4 to 0.8 milligrams of folic acid.
It might sound like a bit much for those who aren't even planning on having children, but as Julia Belluz points out at Vox, roughly half of pregnancies in the US are unplanned, "and the stakes of folate deficiency among babies are very high".
So if we all have to start taking supplements every single day, just how strong is this scientific backing?
The report reassesses its 2009 recommendation - originally based on a meta-analysis of the effectiveness of folic acid supplementation in the prevention of neural tube defects - and combines it with new information from more recent studies.
Based on data from hundreds of thousands of participants from all over the world, and spanning more than three decades, the updated analysis found that the benefits of folic acid supplementation are "well-established, and outweigh the harms" - which is more than can be said for Vitamin D supplements.
For example, one study reported a protective effect of folic acid against neural tube defects, finding that just one neural tube defect occurred in 3,056 women who took folic acid supplements, while nine occurred in 3,056 women who did not.
And a study in Hungary involving 5,453 women, and spanning from 1984 to 1992, reported no cases of neural tube defects in the group taking daily folic acid supplements, and six cases in the control group who weren't.
But wait a minute, I hear you say - hasn't a lot of our food been supplemented with folic acid anyway, so we don't have to bother with the tablets?
As Vox reports, since 1996, the US government has been fortifying cereal grains with folic acid, so it's been ending up in a lot of breads, pastas, and cereals spanning all kinds of brands. Australia has a similar government-regulated policy.
But, as James Mills from the US National Institutes of Health points out in the editorial accompanying the US Preventive Services Task Force's report, it's not worth the risk of leaving things up to supplemented food.
There are certain times where folate levels are more crucial for development than others, and women can't be expected to alter their diets, he points out.
"For example, a women who does not eat enriched cereal grain early in pregnancy, or who is on a diet that eliminates those products may still be at risk," he told Vox.
So ditch the multivitamins and probiotics, and spend your money on folic acid instead. It's not going to do any harm, but could end up doing you and your future child a world of good.