nutrition

Should I Take Vitamin D Once a Day or Weekly? Build a Science-Backed Routine

Dr. Carla Montrond Correia ND, CNS

Medically reviewed by

Dr. Carla Montrond Correia ND, CNS

6 min read

a photo of a woman stretching out her arms on a balcony in the sunlight

Most of us are insufficient in vitamin D. Supplements help but how often should you take vitamin D to get the most benefits from this essential micronutrient?

Many people are at risk of a vitamin D deficiency for multiple reasons. Vitamin D packs a lot of benefits and is an essential part of healthy body functions. If you’re trying to make sure you get enough vitamin D, you may be wondering what the best approach is. Some people wonder if they should take a higher dose of vitamin D less frequently, or if they should take lower doses more regularly. Here, we’ll explore the benefits of vitamin D, the different dosage options available, and where to begin if you think you may have a deficiency.

Benefits Of Vitamin D

Vitamin D, sometimes called the sunshine vitamin, is vital to our health. This micronutrient is necessary for our bodies to absorb calcium and phosphorus; ingesting adequate amounts of vitamin D and calcium will help keep our bones strong. Vitamin D also helps support the functions of our immune system. Vitamin D is typically made by the body when our skin is exposed to the sun. Spending around 15 minutes out in the sun, without sunblock or a significant amount of clothing, exposes the skin to UV B radiation, which is used by the body to create vitamin D.

However, adequate sun exposure can be difficult for a number of reasons. Our busy lives can keep us indoors, weather or pollution can block out the necessary rays of sun, and the melanin in our skin, which acts as a natural sunblock protectant, can interfere with the absorption of UV B rays. Some people who live in parts of the world where the sun’s rays are less intense may also suffer from inadequate levels of vitamin D. And, before you think that you get enough sunlight at work by sitting by a sunny window or due to your car ride in the sun, it’s important to know that most windows block out most of the UV B radiation needed to synthesize vitamin D.

For these reasons, many people rely on a vitamin D supplement to keep them from becoming deficient. Because vitamin D is a fat-soluble vitamin, it is recommended that you take it with a meal that contains foods high in healthy fats. This will ensure that your body absorbs it into your bloodstream properly.

Vitamin D Supplementation

If you’re unsure about whether you’re deficient or not, take a look at your lifestyle first; if you’re still uncertain, your primary care physician can test your blood to ensure you’re getting enough vitamins. When starting a vitamin D supplement, the biggest key to success is to be consistent. Many people find that taking their supplements with a meal is helpful; it’s already something they do every day, and it’s not too difficult to add one more small step to a daily routine.

Vitamin D Supplement Dosage

Once you’ve discovered whether you have a vitamin D deficiency, it’s time to consider your approach to supplements. Some people take a vitamin D supplement every day, either as part of a multivitamin routine or an independent supplement. Others only want to take it once or twice a week. What matters most is knowing where your body’s baseline levels of vitamin D are (at least, where they should be if you aren’t experiencing a vitamin D deficiency!) and reaching those base levels before increasing your vitamin D levels.

The recommended dietary allowance for vitamin D is 600-800 IUs (international units) or 15-20 mcg (micrograms). Generally, doses of 1,000-2,000 IUs or 25-50 mcg are considered adequate maintenance doses; this will ensure that you’re meeting your base levels, plus a little extra! The upper recommended limit is 4,000 IUs or 100 mcg per day. Any more than this without professional guidance could put you at risk of overdoing it.

So what does science say? This study found that taking a 1-2,000 international unit (IU) dose once or twice a week didn’t really change participants’ vitamin D levels. For less frequent dosage, a higher amount is recommended. Overall, though, studies show that the best results come from taking vitamin D as part of a daily regimen, with dosage at the recommended level.

What Happens If You Take Too Much Vitamin D?

Many people think that a higher dose leads to more benefits, but that isn’t always the case. Taking too much of a vitamin supplement can have detrimental effects on your health. As for vitamin D, elevated levels in the body can cause a few problems. The biggest is that it can increase your body’s levels of calcium, causing you to absorb too much. This can cause nausea, vomiting, and frequent urination. Over time, you may also experience bone pain or kidney issues. Fortunately, to reach that level of toxicity, you would need to take a dosage of around 60,000 IUs – far more than any doctor would recommend.

Best Time To Take Vitamin D For Optimal Absorption

As mentioned earlier, the most important part of your vitamin routine is consistency. Vitamin D is best taken alongside a meal, but which meal is entirely up to you. The reason you should take your vitamin D supplements with a meal is that it’s a fat-soluble vitamin; it is absorbed in fat, moved through the body and stored like fat, and our bodies keep a supply of vitamin D in our tissue, to be accessed when needed. For the best results, taking vitamin D daily with a meal that contains healthy fats (such as fish, lean meats, nuts, and oil) is recommended.

Potential Side Effects And Contraindications

There are no known side effects to taking recommended doses of a vitamin D supplement. Taking a higher dose less frequently without being directed to do so by a medical professional can cause side effects. Children, older people, and those who are pregnant or breastfeeding should consult their healthcare provider before taking a vitamin D supplement. Consult your doctor before beginning any new vitamin routine or making any changes to the routine you’re already on, especially if it involves significantly higher doses of a vitamin. As a general rule, it’s important to follow the recommended dosage of any vitamin you consume, unless otherwise directed by a doctor.

Other Sources Of Vitamin D

The best source of vitamin D is sunlight. However, as we’ve explored, this can be a challenge to attain. Enjoying some time outside on a sunny day will help your body get some vitamin D, but it may not be enough, particularly in the winter months. If you want to increase the amount you’re getting, try adding in some egg yolks, fatty fish, beef liver, or fortified foods like milk, juice, and cereal.

Mushrooms are an option for one kind of vitamin D, but they only contain D2, not D3. Since your body needs both to function properly, you will need to supplement accordingly. Additionally, mushrooms do not contain enough of either type of vitamin D to be sufficient on their own. Vegetarians and vegans will need to consider other options to keep their vitamin D levels balanced. Care/of offers both a traditional vitamin D supplement and a vegan formula to help ensure you get enough of this micronutrient.

Final Takeaways

Vitamin D is necessary for our health, especially our bone health and immune system. While it is possible to take enough vitamin D once a week to keep yourself balanced, the best results were found to be a lower dose (1,000-2,000 IUs or 25-50 mcg ) taken daily. Taking vitamin D consistently with a meal containing healthy fats will ensure that your body absorbs it properly.

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