If you're trying to conceive, are already pregnant, breastfeeding or just want to maintain a healthy diet, understanding how vitamins work is an essential first step.
Vitamins are nutrients that our bodies need in small amounts to function properly, most of which we get from our food (especially fruits and vegetables).
Important minerals, which work in a similar way, include calcium, phosphorus, potassium, sodium, chloride, magnesium, iron, zinc, iodine, chromium, copper, fluoride, molybdenum, manganese, and selenium.
The amounts of vitamins and minerals, such as folate and vitamin D, that you need may change over your lifetime, meaning that additional supplements may be required at specific points.
But with so many variables involved, it is often hard to know how long to wait to assess the effects of a new vitamin you've added into your routine.
The short answer is: it depends on the type of vitamin you take and your current level of that particular supplement. It could be a few weeks to a few months before you see the full results, especially if you start from a low baseline.
However, the more deficient you are in a particular vitamin, the more quickly you will feel some kind of change.
Of course, many vitamins will begin to have an effect on your body soon after you take them, but each substance will need to build up before you can see or feel a physical difference. Read on for more detailed information about the timeframe for common supplements.
Water soluble vitamins vs fat soluble vitamins: what's the difference?
All vitamins can be classified as either water-soluble or fat-soluble, which refers to how they are stored in the body. The major fat-soluble vitamins are vitamins A, D, E and K, while vitamin C and the B group vitamins (including folate) are water-soluble.
Being able to differentiate between these can be helpful when it comes to figuring out dosage and timings because fat-soluble vitamins can be stored in the liver and fatty tissues of the body [1].
This means most people are less likely to be deficient in fat-soluble vitamins because the body is able to maintain a backup supply.
To prevent excessive build-up, watch the quantities of fat-soluble supplements you consume because extremely high levels of these substances can cause health problems.
Water soluble supplements are the faster-acting of the 2 types, thanks to the ease with which they can enter the bloodstream.
On the other hand, any surplus water-soluble vitamins will be rapidly flushed out of the body, so taking too many vitamin C tablets rarely results in any negative side effects [2].
Plus, if you are deficient in a water-soluble vitamin, you may be able to feel the effects much more quickly as they are rapidly absorbed into the body.
How are vitamins processed by the body?
The distinction between the 2 main types of vitamins determines how they are processed.
Fat-soluble vitamins are usually found in animal fats, vegetable oils, dairy foods, liver and oily fish, as well as in vitamin supplements. Minerals are mostly absorbed into the body in a similar way to either fat or water-soluble vitamins and are just as important to keeping well.
When consumed, the intestine absorbs fat-soluble vitamins and then releases them into fatty tissue throughout the body or stores them in the liver until needed.
Because the body can store these substances, you don't need to have them every day, but regular consumption is recommended to maintain the desired levels.
On the other hand, water-soluble vitamins can be ingested by eating fruit and vegetables, grains and milk and dairy foods. This can also be supplemented with vitamin tablets.
Whether consumed in food or as a supplement, water-soluble vitamins are absorbed into the bloodstream during digestion and then carried directly to the part of the body where they are needed.
Excess vitamin supply is flushed out when you urinate. The body can only process a small quantity of these at a time, so you need to eat them almost daily.
How does your body use vitamins?
Each vitamin serves a particular purpose, but all are essential nutrients for a healthy body.
Whether consumed in food or as tablets, vitamins start in the digestive tract, travelling from the mouth through the oesophagus into the stomach, where they are broken down by stomach acids.
The nutrients then move to the small intestine, where the water-soluble vitamins are picked up by molecules that transport them directly into the bloodstream. The fat-soluble vitamins are further broken down by bile acids and carried to the liver and fatty tissue.
From their final destinations, vitamin D can strengthen bones, while vitamin B12 helps keep nerve and red blood cells healthy which results in increased energy levels and brain function.
Vitamins C and E can prevent cell damage and vitamin A can slow the effects of macular degeneration (a common eye disorder that causes blurred vision). Vitamin K helps make proteins that are needed for blood clotting and strong bones [3].
Folate is unique because it helps with the development of a baby's brain, skin and spinal cord. Although folate is water soluble, people's ability to absorb folic acid (the most common form included in a prenatal supplement) varies.
In this case, methylated folate can be a good substitute [8]. Zinc and selenium have also been shown to have a positive effect on sperm health, making them a worthwhile investment when trying to conceive [9].
Do vitamins take effect immediately?
Water soluble vitamins such as B vitamins can start to work almost immediately, but it's unlikely that the effects will be physically noticeable for at least a few hours. The effect will be even faster if you are severely deficient, but it could take weeks or months to restore the human body to healthy levels.
Fat-soluble supplements will generally have more subtle effects over time.
Additionally, certain nutrients work faster when paired with other substances that increase vitamin absorption, sometimes referred to as bioavailability. These combinations include iron and vitamin C, as well as vitamin D and calcium [4].
How long do vitamins take to work?
Certain vitamins are more easily absorbed than others, meaning it is difficult to provide an exact timeframe.
Generally speaking, water-soluble vitamins work within days, while fat-soluble vitamins can take weeks or months. Some only need to be taken for a limited time period before feeling the beneficial effects, but the dose and duration will depend on why you're taking supplements.
Key vitamins for particular physical or dietary factors may only need to be taken for a limited time. These include folate, which should ideally be taken for 3 months before conception and during the first 12 weeks of pregnancy and B12, which may be low in people who don't consume animal products.
The sun is the best source of vitamin D. For most people in Australia, vitamin D levels are maintained through incidental sun exposure while you're out and about. In summer, a few minutes outdoors is enough [7].
Vitamin D, which can be absorbed from food as well as sunlight, is harder to come by during the winter months, especially for older people. In this case, a vitamin supplement can be recommended.
How do you know when vitamins are working?
The easiest way to tell that a specific nutrient is working is that your body goes back to its normal functioning levels.
One of the most common symptoms of vitamin deficiencies is low energy, so you may be able to feel a difference in your levels of fatigue after a few days or weeks of taking supplements [5].
Other supplements, like folate and iron during pregnancy, have effects that cannot be seen or felt at all.
The best place to start is by making sure you eat a balanced diet, but if you find that supplements are necessary it is worth taking them for a couple of months before judging the effects.
Signs of a serious nutritional issue include brittle hair and nails, mouth ulcers, bleeding gums, brain fog, impaired eyesight and scaly patches or discoloured skin [6].
It is highly recommended that you consult a doctor if you notice any of these symptoms. In the case of diagnosed deficiencies, your doctor will conduct comprehensive nutritional testing to monitor your health.
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