With the new year comes a fresh set of “healthy” resolutions

And it is true, vitamins can do wonders. Just think of magnesium for a better night’s sleep, iron for an energy boost, or vitamin D to help you power through what feels like the never-ending month of January.

However, despite the benefits these supplements may offer, it is wise to think twice before taking them all at once as part of your “new year, new me” morning routine. A warning has been issued about a dangerous vitamin combination that should never be taken.

Some vitamins can counteract each other, reducing their effectiveness at best and potentially causing unpleasant side effects, long-term nutritional deficiencies, or even vitamin toxicity, according to Brynna Connor, M.D., a board-certified family medicine physician at Northwestpharmacy.com.

"Many people don’t realise how much timing matters when it comes to supplements," adds Amy Margulies, R.D.N., a registered dietitian nutritionist. "Some are better absorbed with food, while others are best absorbed on an empty stomach. Other combinations can actually interfere with each other or with medications."

So, which vitamin combos should you avoid?

Iron and Calcium

Calcium blocks iron absorption in the gut.

Taking these two vitamins together isn't the best idea, however, if both levels are low, you can still take each one, just be sure to consider the timing.

Health experts recommend taking iron at least two hours before or after consuming calcium-rich foods, such as dairy products, leafy greens, or canned fish with bones, or taking calcium supplements.

Additionally, it's important to note that calcium carbonate needs food as it relies on stomach acid.

Iron and zinc

Iron and zinc compete for the same absorption pathways in the gut

"If you’re taking a high-dose iron supplement and zinc at the same time, especially on an empty stomach, there’s a good chance your body won’t absorb the zinc as well," says Dr Margulies.

She goes on to recommend taking iron with food, just not with calcium, and to keep it separate from zinc.

Additionally, zinc is best on an empty stomach, since particular foods interfere with absorption.

Copper and zinc

It is understood that high doses of zinc can reduce copper absorption, and over time, this could lead to copper deficiency.

To help balance this, you can consider consuming copper-rich foods such as shellfish, seeds, nuts, and organ meats. However, regular blood tests remain advised.

If you require both copper and zinc, health experts recommend separating them by at least two hours. Both can be taken on an empty stomach.

"You can take zinc in the morning before breakfast and copper before lunch or dinner, provided you have not consumed a meal or snack within at least a few hours," says Margulies.

Calcium and magnesium

Calcium and magnesium compete for absorption in the digestive system, so taking them together in high doses can lead to bloating or diarrhoea, says Dr Connor.

It's recommended to take them separately, with at least a two-hour wait.

Calcium is best taken in the morning, particularly calcium carbonate with food, while magnesium is ideal in the evening because of its calming properties.

Vitamin B12 and vitamin C

Vitamin C is known to create a rather acidic environment, and large doses can degrade vitamin B12 before it actually starts working.

Dr Connor, therefore, suggests taking them alphabetically. Take vitamin B12 first, then wait at least two hours before vitamin C.

B12 can be taken on an empty stomach or with a light breakfast.

Before adding any supplements, even natural ones, it is best to consult your healthcare provider. They can help you avoid interactions with medications, particularly blood pressure drugs, thyroid medications, and anticoagulants, says Dr Connor.

"It’s always best to stick to a routine when it comes to taking your vitamins and minerals," she added. "Once you know how to space them out safely, taking them at the same time each day can improve absorption and consistency," per Tyla.