Hold on a moment. It appears that this isn’t entirely accurate. Like any supplement or medication, adverse effects from multivitamins aren’t rare occurrences. (And in certain instances, they may not deliver the benefits they profess to provide). If you’ve experienced gastrointestinal problems, for instance, it could be due to your multivitamin.
Side effects of multivitamins to keep an eye on
“While most multivitamins, when taken at the correct dosage, are considered safe and typically devoid of side effects, some individuals might encounter a few uncomfortable reactions,” states Amanda Wahlstedt, RDN, CDN, MSc, a registered dietitian at Roots to Leaves. She highlights constipation, diarrhea, upset stomach, and nausea as the most frequently reported side effects of multivitamins.
These effects can arise when someone ingests excessive amounts of a specific nutrient or has a sensitivity to a particular ingredient. For instance, vitamin C may irritate the stomach lining, while iron has been known to lead to constipation and bloating when it isn’t absorbed effectively, Wahlstedt explains.
“I’d also be mindful of signs like insomnia and headaches,” she notes. “While these side effects are rarer, they may indicate that your multivitamin isn’t suitable for you. If you experience symptoms like hives, swelling of the face or tongue, or difficulty breathing, this may signify an allergic reaction, and you should seek emergency medical assistance.” Regardless of their severity, any of these symptoms could be linked to multivitamin side effects.
Who should steer clear of multivitamins?
While multivitamins are generally safe for many individuals to use regularly, certain groups may want to refrain from taking them entirely.
Pregnant individuals, for example, should be particularly cautious about consuming multivitamins. Laura Purdy, MD, MBA, a board-certified family medicine physician known as “America’s Favorite Doctor,” advises that they “must only take specific supplements at lower dosages or avoid them altogether.” If you are pregnant or trying to conceive, Wahlstedt recommends steering clear of multivitamins with high vitamin A levels to promote a healthier pregnancy (prenatal vitamins are a preferred alternative).
Moreover, vitamins and supplements can interact with your body and medications more than one might assume. “Given that many multivitamins now incorporate ‘special’ ingredients like herbs and adaptogens, it’s always wise to consult with a physician or dietitian before starting them, to ensure there are no interactions with other medications and that they are suitable for your specific health situation,” Wahlstedt advises.
Individuals with liver disease, compromised immune systems, kidney issues, or those receiving radiation or chemotherapy treatments should exercise additional caution regarding supplement use. Regardless of health history, it is typically advisable to consult your healthcare provider before introducing anything new into your regimen.
Signs of vitamin toxicity
To ensure safety, be aware of symptoms that may suggest an overload of vitamins (even if you think you’re doing fine). Keep in mind that your symptoms will vary based on which vitamin is in excess. Wahlstedt provides some instances:
- Excessive vitamin D (commonly present in multivitamins): nausea, vomiting, constipation, dehydration, muscle weakness, among others
- Too much vitamin A: headaches, stomach pain, vomiting, blurred vision, as well as alterations in skin, hair, and nails
“Generally speaking, if you observe a decrease or sudden shift in appetite, digestion, energy levels, or changes in skin/hair/nails after taking vitamins, it’s advisable to consult with your doctor or dietitian,” Wahlstedt emphasizes.
Is vitamin overdose possible?
Is there a risk of severe consequences if too many vitamins are taken? In brief, yes. Overdosing can indeed occur, so it’s critical to heed the guidelines on the bottle (and from your physician) regarding vitamin intake and dosage. Additionally, some vitamins can be more damaging than others. “Specifically, vitamins A and iron pose heightened risks when consumed above suggested levels on their labels,” Dr. Purdy warns.
Your safest course of action is to proceed with caution. “While certain vitamins carry more risk than others, particularly fat-soluble ones that can accumulate in the body, and certain minerals such as iron and calcium, it’s generally advisable to remain within the recommended daily intake for all supplements,” Wahlstedt advises. “While exceedingly rare, overdosing on vitamins can result in liver damage, organ failure, or even death.”
If you’re already taking another vitamin or supplement, adding a multivitamin might lead to excess intake. Consult your healthcare provider to ensure you’re not exceeding safe limits.
Effects on your body when starting vitamin supplementation
Despite potential side effects, multivitamins have their advantages. Positive outcomes noted by Wahlstedt include healthier hair and nails, improved sleep, and more manageable menstrual cycles. Another benefit, highlighted by both her and Dr. Purdy, is increased energy. On the cognitive front, recent research published in The American Journal of Clinical Nutrition suggests that multivitamins can enhance memory in older adults.
However, Dr. Purdy notes that these effects “may or may not be immediately noticeable” and could take time before they manifest—if they manifest at all. Wahlstedt mentions that noticeable effects usually begin to appear after three to six weeks of consistent and proper use.
“If you’re taking a multivitamin thoughtfully and appropriately, you should start to feel improvement,” Wahlstedt states. “However, for those who aren’t deficient in vitamins initially, you may not see much difference from starting a multivitamin.”
Also, remember that obtaining vitamins and minerals from natural sources, such as food, is often the most effective approach. For example, boosting vitamin D could involve consuming mushrooms, egg yolks, and fatty fish, along with getting a bit of sunlight for five to ten minutes several times a week.
If that’s not feasible for you, don’t worry! Multivitamins can still assist—if used properly. “To ensure maximum effectiveness and safety, select high-quality products from trustworthy sources,” Dr. Purdy advises.
But what if you find that a multivitamin is causing you digestive discomfort or an allergic reaction? Wahlstedt suggests alternatives like changing the brand, lowering the dose, using a more bioavailable form (like iron bisglycinate), taking it with food, or pairing it with ginger or B6 to mitigate nausea. Your primary care physician or dietitian can guide you toward the best approach for your situation.
What is the ideal multivitamin dosage for adults?
Both Wahlstedt and Dr. Purdy emphasize that the “correct” dosage—or even more crucially, the “incorrect” one—depends on various factors, including your age, gender, individual health requirements, and other circumstances. Therefore, it’s essential not only to avoid overdosing (or experiencing multivitamin side effects) but to refrain from presuming your needs based on how much a friend or sister takes. Until you consult more with your physician, the best and safest route is to follow the dosage recommended on the bottle.
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