Do You Really Need a Multivitamin Every Day, or Are You Taking Nutrients You Already Get From Food?

Taking a multivitamin is kind of like cheap insurance. Yet if you're already eating a wide-range of fruits and vegetables, you might be spending too much money on supplements that you already receive from food. Studies of multivitamins in the general population have not revealed such dramatic improvements as would be suggested by the packaging and there are some populations that clearly benefit. To find out which group you've been assigned to:

Key Takeaways

• The evidence of a multivitamin being beneficial to prevent heart disease or cancer is limited in healthy, well-nourished adults and a multivitamin cannot replace a balanced diet.

• Women who want to conceive, pregnant women, those on a strict vegan diet, older adults with poor absorption of B12 and those with restricted diet or absorption issues have a reason to supplement.

• Taking multiple supplements and fortified foods can cause some nutrients to exceed the upper limits of safety.

• Stay away from high doses of beta-carotene and vitamin A supplementation when smoking and vitamin K should be carefully administered to those taking warfarin.

• When selecting a multivitamin, choose one that contains nutrients that are around 100% of the daily values and not mega doses.

What the Research Shows

The Office of Dietary Supplements at the National Institutes of Health (NIH ODS)2 assesses the research on multivitamin and mineral supplements. Key findings include:

• In 2022, an evidence review for the US Preventive Services Task Force found 78 RCTs and found the evidence to be insufficient to recommend multivitamins for preventing cardiovascular disease or cancer.

• The Physicians' Health Study II (14,641 male physicians followed for a median of 11.2 years) showed no effect of daily multivitamin on major cardiovascular events. This correlated to an 8% reduction in cancer overall.

• In the Women's Health Initiative, which included 161,808 postmenopausal women, there was no relationship between using multivitamins and cancer, cardiovascular disease or death.

• The COSMOS trials included over 5,000 older adults, and found that a multivitamin improved episodic memory, executive function and global cognition. These are promising although yet to be confirmed and refer to older adults, rather than the general population.

Who May Benefit

A dietary supplement may be beneficial for the following reasons:

Group	Why a supplement may help	Notes
Women planning pregnancy or in early pregnancy	400 mcg of folic acid daily reduces the risk of neural tube defects	Prenatal products are also linked to lower rates of low birth weight and preterm birth
Adults aged 50 and over	Absorption of B12 from food often falls with age	NIH ODS recommends B12 from supplements or fortified foods for this group
Strict vegetarians and vegans	B12 occurs naturally only in animal products and deserves attention	Iron, Zinc, Iodine and Vitamin D may also require consideration
People with limited sun exposure	Vitamin D may be low	See Article 5
People with digestive disease, bariatric surgery, or very restricted diets	Absorption or intake may be reduced	Needs individual advice

Group	Why a supplement may help	Notes
Breastfed infants	Give 400IU vitamin D each day	given as drops, as per a paediatrician's advice.

A standard multivitamin may not be very helpful in the context of eating a mixed diet, which includes vegetables, fruits, whole grains, protein foods, and dairy or dairy alternatives.

Side Effects and Precautions

There are a few side effects and precautions.

• Stomach upset. Nausea/constipation may happen, frequently due to Iron. It can be taken with food.

• Doubling up. Fortified cereals, energy drinks, protein powders and supplements are available separately and provide extra nutrients. Check the total.

• Smokers. Beta-carotene, both consumed as a single, large dose supplement and as preformed vitamin A, has been linked to higher risk for lung cancer in smokers (18% to 28% depending on the studies cited by NIH ODS).

• Pregnancy. High levels of preformed vitamin A (retinol) can cause birth defects. Pregnancy specific products.

• Warfarin. Taking vitamin K as part of a multi-vitamin can cause it to have less effect on this blood thinner. Please consult your doctor or pharmacist prior to starting one.

• Mineral interactions. Some antibiotics and thyroid medications are not absorbed well with calcium, iron, and magnesium.

How to Choose a Multivitamin

1. Compare it to your age – pregnancy, grown up, over 50 or vegan formulas provide various quantities.
2. Try for percentages that are about the 100% Daily Value, not 500% or higher.
3. Inspect for third party testing and/or Quality marks and for Approved to National Regulator.

4. Take one product at a time and inform the doctor/pharmacist of what products you are taking.

Frequently Asked Questions

• Can a multi-vitamin supplement compensate for a bad diet? While it can be used to make up some of those deficiencies, it doesn't provide the fibre, healthy fats, protein or all the other compounds in the whole food. Is it better to take a multivitamin with food? Many people do better taking it with a meal and fat soluble vitamins (A, D, E, K) are better absorbed with some fat in the meal.

• How about Gummy Multi-Vitamins? They may be low in nutrients or lack iron. Read the label. So should I take a multivitamin on Ramadan? Generally, a balanced meal would suffice at suhoor and iftar. Speak to a doctor or pharmacist if you have a medical condition or take regular medicines.

 Conclusion

As long as healthy adults enjoy a balance diet, there's no need to take a daily multivitamin supplement. But, for pregnant women or those thinking of getting pregnant, older people, strict vegans and those who have trouble with absorption, it can fill certain, clearly defined gaps. If you choose to take one, ensure it is straightforward, that you take the recommended dosage, and tell your doctor if it.

This article is for general education and does not replace advice from a doctor or pharmacist.

References

1. National Institutes of Health, Office of Dietary Supplements. Multivitamin/mineral Supplements: Fact Sheet for Health Professionals.

https://ods.od.nih.gov/factsheets/MVMS-HealthProfessional/

2. National Institutes of Health, Office of Dietary Supplements. Vitamin B12: Fact Sheet for Health Professionals.

https://ods.od.nih.gov/factsheets/VitaminB12HealthProfessional/