How long does it take for vitamins to work? One day, two weeks, three months, or maybe longer? When it comes to feeling the benefits, there’s no single answer, thanks to a variety of factors that impact vitamin absorption – from the type of supplement you’re taking to the ways certain nutrients interact with each other in the body.
To get some clarification on the matter, we spoke with Dr Luke Pratsides, lead GP at online healthcare clinic Numan; Dr Carrie Ruxton, dietician at the Health & Food Supplements Information Service; and Clarissa Lenherr, nutritionist for personalised healthcare service Bioniq:
How long does it take for vitamins to work?
On a biological level, vitamins are absorbed ‘in a matter of hours’ and have ‘immediate metabolic effects – for example, acting as antioxidants to protect cells, or as intermediary substances involved in making hormones,’ explains Dr Ruxton.
However, there are a number of factors that can impact their efficacy and prevent your body from absorbing them fully – or at all:
1. Deficiency levels
If you’re extremely deficient in a particular vitamin or mineral, it could take longer to rectify the deficiency. Alternatively, you may require a higher dose in order to help you recover to those levels faster, says Dr Pratsides.
‘If you are taking them because you have been diagnosed as deficient in a specific vitamin or mineral that is causing a side effect like tiredness, it can take much longer to build back up to optimal levels than if you are just taking them on a precautionary basis,’ he says.
2. Type of supplement
Vitamins taken in liquid form will often have a faster effect than a capsule, explains Lenherr. ‘This is because the body has to break down the capsule to extract the vitamins inside,’ she says.
Capsules and tablets contain limited doses, ‘which means they may not be able to accommodate as much of the supplement,’ while liquid and powder formats may be less effective due to the way they are made.
‘Liquid and powdered supplements are limited in that when mixing certain vitamins and minerals together, they can block their absorption, and there is no way of separating them physically unless you take two separate supplements,’ Lenherr adds.
Granulated supplements, meanwhile, ‘allow for many nutrients and minerals to be delivered together without blocking absorption,’ she says, since the nutrients are separated out.
3. Water vs fat-soluble vitamins
Certain nutrients are fat-soluble, such as vitamins A, D, E and K, says Lenherr. ‘This means they require fat to be absorbed and this can be achieved by mixing these nutrients with a fat in the capsule or liquid, or through taking them with food,’ she says.
‘Fat-soluble vitamins are stored in the body and therefore may not need as high or regular doses as water-soluble vitamins.’ Water-soluble vitamins, meanwhile, dissolve in water and are easily absorbed into tissue, ‘which means they may have a slightly faster effect,’ Lenherr says.
4. Nutrient pairings
Many vitamins and minerals are interrelated in how they work, says Dr Pratsides. ‘A good example of this would be the relationship between vitamin D and calcium,’ he says. ‘Vitamin D helps your body absorb calcium, so if you have low levels of vitamin D, you will struggle to maintain a healthy calcium level without high intake of calcium-rich foods.’
That’s not the only example. Plant-based iron is best absorbed when paired with vitamin C, and vitamin B6 relies on zinc to function optimally, while curcumin (the key compound in turmeric) is very poorly absorbed unless taken with piperine, which increases absorption by 2,000 per cent.
This pairing system works both ways. For example, zinc and copper compete with one another for absorption in the small intestine. ‘When paired together in a supplement, you may end up with less copper absorption, as the recommended intake for zinc is higher than copper,’ says Lenherr.
5. Lifestyle and habits
Certain lifestyle factors and habits, such as drinking alcohol and smoking, can cause malabsorption and require a higher intake to maintain an equilibrium.
Caffeine can block the absorption of certain nutrients such as vitamin B6, calcium, iron and magnesium, advises Lenherr. ‘Time caffeine intake to 45 minutes before or after any supplements,’ she suggests.
6. Health issues
Certain health issues can also impact absorption. ‘Some people cannot absorb certain vitamins due to gut disease like coeliac or inflammatory bowel disease or because they lack hormones like intrinsic factor – which is crucial in B12 absorption,’ says Dr Pratsides.
Alternatively, they directly increase your body’s requirements. ‘Obesity increases the inflammatory response, which increases the requirement for anti-inflammatory nutrients such as long chain omega-3s,’ says Dr Ruxton.
What are signs that vitamins are working?
This is dependent on each and every person and which vitamin combination they are taking, says Lenherr. ‘It is also dependent on age, gender, digestive health, pre-existing levels, diet, pre-existing medical conditions and more,’ she says.
It’s more helpful to look for signs of deficiencies, which vary depending on which supplement you’re deficient in. ‘It is unlikely that you will feel or see anything if you’re nutritionally replete – however, you will notice signs of fatigue, poor skin or nails if chronically lacking nutrients and these are all signs to look out for,’ says Dr Ruxton.
Individual vitamins vs multivitamins
Which is better? Generally speaking, unless you’re trying to combat a specific deficiency, a multivitamin is your best bet.
Taking several different supplements singularly in pill format can cause nausea and other adverse side effects, says Lenherr. ‘A multivitamin blended into granules will release active ingredients into the blood stream during a sustained period to enhance absorption in the body,’ she says.
While you may not necessarily need all the vitamins within, ‘it shouldn’t cause any major issues as the majority of excess supplementation will be excreted,’ says Dr Pratsides.
How long should you wait before switching vitamins
Three months should be long enough to assess whether you feel any benefits. But again, it depends on why you’re taking vitamin supplements in the first place, says Dr Pratsides – i.e. whether you’ve been diagnosed as deficient in a specific vitamin, or you’re just taking them as a precaution. ‘Ultimately everyone is different, and regular testing will help to assess the impact the supplementation is having,’ he says.
If you stop taking the vitamins but don’t ensure that you have a healthy, balanced diet, blood levels of nutrients will decrease, says Dr Ruxton. ‘Correcting low blood levels can take anywhere from a few weeks to several months,’ she says. ‘For example, 90 per cent of women of childbearing age don’t have adequate blood folate levels, while a third have low iron stores – this can’t be fixed in a few days.’
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