Nutritionist Rachel Woods: "5 things I wish people knew before buying supplements"

Nutritionist Rachel Woods has summarized for The Conversation the “5 things I wish people knew before buying supplements.” These products, which range from collagen powder to popular immune-boosting gummies , are found on social media, in supermarkets, and in medicine cabinets. Although they are advertised as quick fixes for better sleep , improved skin, or improved concentration, Woods cautions that their benefits are not always scientifically backed and that their use should be analyzed with caution.

The expert's first recommendation is clear: prioritize obtaining nutrients through food before resorting to capsules or powders. Whole foods offer unique combinations of vitamins, minerals, and other compounds that work together, as is the case with salmon , which is rich in omega-3 , vitamin D , and selenium . Still, she acknowledges that there are cases where supplementation is necessary, such as folic acid during pregnancy, vitamin D during months with little sunlight, or B12 in vegan diets.

Second, it warns about the risk of taking too many vitamins . Fat-soluble vitamins — A, D, E, and K — can build up in the body and cause kidney, liver , or bone damage . Even water-soluble vitamins, like B6 , can cause nerve damage if taken in excess over long periods. Many people don't monitor their levels with tests and only discover the problem when symptoms appear.

Woods also warns of the large number of advertising messages disguised as advice circulating on the internet and social media. Words like "detox," "natural," or "boosts the immune system" have no scientific definition and are part of marketing strategies . In the case of multilevel marketing , she points out that salespeople often lack medical training and rely on personal experience , which can lead to unnecessary or unsafe consumption .

Another key aspect is that the dietary supplement industry is worth more than $100 billion worldwide, and its main goal is to generate profits . The nutritionist emphasizes that while some products are backed by scientific evidence —such as iron or vitamin D —others are promoted with exaggerated promises . If a supplement had a proven effect , it would be recommended by health professionals , not just celebrities or influencers .

Finally, remember that not all supplements are safe for everyone . Examples such as St. John's wort , which can interfere with antidepressants or contraceptives , or vitamin K , which disrupts the action of blood thinners , show the importance of consulting a doctor or pharmacist . Furthermore, some have not been tested on pregnant women , and high doses of vitamin A can be dangerous during pregnancy . Her final advice is clear: always make sure the supplement is safe and actually necessary .