Warning issued over 'dangerous' vitamin combination you should never take

If one of your New Year's resolutions was to take your health more seriously, you may have found yourself with a whole pantry stocked with vitamins and supplements.

Whether it's vitamin C to ward off those January bugs, magnesium to help you sleep better, iron for more energy or vitamin D for this horrific winter weather - it's clear that, when taken correctly, these little pills can work miracles for our bodies.

However, you may want to think twice before you do an 'all-at-once' vitamin-taking routine, as a warning has been issued over a 'dangerous' vitamin combination you should never take.

Despite its convenience, it's important to note that some vitamins can counteract each other, reducing their effectiveness at the very least and potentially causing some pretty unpleasant health side effects at the most.

There are a few vitamin combinations that health experts have strongly advised against (Getty Stock Images)

In the worst-case scenario, long-term nutritional deficiencies and vitamin toxicity can occur, says Brynna Connor, M.D., a board-certified family medicine physician at Northwestpharmacy.com (via Good Housekeeping).

"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, according to the experts, which vitamin combos should you avoid?

Iron and calcium

Calcium blocks iron absorption in the gut, so taking them together is far from a good idea.

If both levels are low, you can still take each one, but be sure to consider timing. Experts suggest taking iron at least 2 hours before or after calcium-rich foods such as dairy, leafy greens, or canned fish with bones, or calcium supplements.

Calcium absorbs best in smaller doses of 500 milligrams or less, spread across the day, says Lamees Hamdan, M.D., an integrative medical doctor. Calcium citrate can be taken with or without food.

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

You may want to think twice before your next 'all-at-once' vitamin-taking routine (Getty Stock Images)

Iron and zinc

Iron and zinc also clash as they 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.

The expert recommends taking iron with food, just not with calcium, and keeping it separate from zinc.

Zinc is usually best on an empty stomach, since certain foods interfere with absorption, and if it causes nausea, a small snack is fine.

Avoid foods rich in calcium, iron, or fibre when you take them, Margulies adds.

Copper and zinc

High doses of zinc can reduce copper absorption and, over time, that can lead to copper deficiency.

Copper-rich foods such as shellfish, seeds, nuts, and organ meats can help balance this, but regular blood tests are important.

If you need both, experts recommend separating them by at least two hours. Both can be taken on an empty stomach, too.

"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.

Some vitamins seriously clash when taken together (Getty Stock Images)

Calcium and magnesium

Calcium and magnesium compete for absorption in the digestive system, meaning that, when taken together in high doses, they can cause bloating or diarrhoea, says Dr Connor.

Take them separately, with at least a two-hour gap.

Calcium works well in the morning, especially calcium carbonate with food, while Magnesium suits the evening, thanks to its calming effects.

Vitamin B12 and vitamin C

Vitamin C creates an acidic environment, and large doses can degrade vitamin B12 before it does its job.

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

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

Before starting any supplement, even a natural one, check with your healthcare provider, as this helps avoid interactions with medications, especially blood pressure drugs, thyroid medication, and anticoagulants, Dr Connor says.

"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."