The Beginners Guide to Vitamins & Multivitamins


Vitamins, especially multivitamins, are extremely popular dietary supplements.

In fact, the National Institute of Health reports that more than half of Americans take multivitamins.

Many people take them for increased energy, a stronger immune system, or to make up for nutritional gaps in their diet.

Because of their popularity, there is an overwhelming number of options to choose from, and a lot of things to consider before deciding which formula to buy.

This detailed guide to vitamins provides an in-depth view of what you should be taking and why, as well as the best way to incorporate them into your daily routine.

Understanding the Basics of Multivitamin Supplements

Multivitamins usually contain essential vitamins and minerals in one supplement. Every formula is created differently, with a different combination of nutrients. They come in a variety of formats, including liquids, powders, gummies, pills, capsules, and chewable.

Some formulations also contain other nutrients like omega-3 fatty acids, probiotics, amino acids, and herbs in addition to vitamins and minerals. There’s no specific guideline or standard formula for what a multivitamin supplement must contain.

Each individual manufacturer chooses its own ratio of nutrients and which ones to include. That’s why it’s so important to do your research before making a decision about which multivitamin to purchase.

The Three Most Common Types of Multivitamins

Although there are many different types of multivitamins on the market, these three are the most common.

Once Daily Vitamins

Once-daily formulations are basic multivitamins that are meant to be taken once each day. They usually contain the basic minerals and vitamins required for health in the recommended daily amounts, or DRIs (Daily Recommended Intake). Once-daily vitamins are often created in formulations that are meant to meet specific nutritional needs, such as prenatal, children’s, senior, men’s, or women’s specific formulas.

Megadose Vitamins

Megadose multivitamin formulas generally contain higher amounts of nutrients than the DRIs. They also include other nutrients like herbs. These formulas are usually targeted to meet the increased nutritional requirements of certain health conditions, to boost immunity, or increase energy levels.

Specialized Multivitamin Formulas

Specialized vitamin formulas are similar to megadose formulas, but they’re more targeted to specific health goals or health conditions. These formulas generally include additional ingredients such as herbs, probiotics, and more.

Deciding which type of multivitamin you should take all comes down to your personal needs. While a basic once-daily vitamin can help to fill in some of the nutritional gaps in your diet, megadose or specialized vitamins can do more to help you meet specific health goals, such as increased energy, a stronger immune system, or relieve the symptoms of certain health issues.

No matter which type of multivitamin formula you choose, big-name industry experts at SmartyPants Vitamins recommend choosing organic vitamin formulas that are free of additives and other contaminants.

Common Nutrients Found in Multivitamins and What They Do

Although every brand is formulated differently, they will generally contain some combination of 14 vitamins and minerals. Here’s an overview of each one and how they affect the body.

  1. Vitamin A: Vitamin A supports the immune system and the health of your bones, skin, and eyes.
  2. Vitamin C: Vitamin C is well known for its ability to boost the immune system, but it’s also an important antioxidant that protects against premature aging. It also improves the absorption of iron into the bloodstream.
  3. Vitamin D: Vitamin D is essential for healthy bones. It also strengthens the immune system and reduces inflammation.
  4. Pantothenic Acid: This vitamin is needed to convert food into cellular energy and making red blood cells.
  5. Vitamin E: Vitamin E protects the cells against inflammation and promotes heart health.
  6. Riboflavin: Riboflavin is essential for proper cell growth, development, and function. It helps the body metabolize drugs, fats, and other substances. It also increases energy production.
  7. Thiamin: Thiamin is necessary for converting food into energy for the cells and it also supports cellular function and growth.
  8. Vitamin B6: Vitamin B6 helps the body metabolize proteins and convert food into energy for the cells.
  9. Niacin: Niacin helps the body convert food into energy for the cells and supports the synthesis of cholesterol and fatty acids.
  10. Vitamin B12: This vitamin boosts energy production. It’s also essential for the formation of red blood cells and a healthy brain.
  11. Folic Acid: Folic acid is especially important for women of childbearing age because it may prevent birth defects. It also supports the body’s ability to metabolize amino acids.
  12. Zinc: Zinc is a mineral that promotes the healing of wounds and boosts the immune system.
  13. Iron: Iron is necessary for transporting oxygen throughout the body and creating new red blood cells. It also supports metabolism.
  14. Calcium: Calcium is necessary for strong bones and muscles.

Vitamin D3: What Does it Do? How Much Should I Take Daily?

vitamin d3Vitamin D3, otherwise known as Cholecalciferol, or “the sunshine vitamin”, is a unique vitamin produced by the skin when exposed to sunlight.

Although naturally produced by the body, people often take extra amounts of vitamin D3 to enjoy its many health benefits.

In fact, it can also be found in foods, and consumed as part of a healthy diet of fish, cheese, and eggs. In the US, some foods, such as milk, have extra vitamin D3 added to them.[1]

With all this in mind, let’s take a look at vitamin D3, what it is, its benefits, and how it differs from other kinds of vitamins.

What is vitamin D3?

Vitamin D3 is a type of vitamin D that is produced by the skin when exposed to UVB light. The vitamin is then converted in the liver into a chemical known as calcifediol, which is the storage form of the vitamin.

From there, calcifediol is then converted into calcitriol within the kidneys. As a result of this process, the body can increase its uptake of calcium.[2][3]

What does vitamin D3 do?

Vitamin D3 is an important component in the healthy growth of bones and a deficiency of the vitamin can lead to brittle or misshapen bones.

In children and younger adults, healthy amounts of vitamin D3 can prevent rickets and osteomalacia. For older adults, a healthy intake of vitamin D3 protects against osteoporosis.

Aside from the maintenance and growth of bones, the vitamin has other roles in the body, such as the modulation of cell growth and neuromuscular and immune function. Vitamin D3 is also known to help reduce inflammation.[4]

As vitamin D3 is produced as a result of exposure to sunlight, it is often the case that people living in colder climates suffer from vitamin D3 deficiencies.

People can also suffer from a deficiency of vitamin D3 if they are older, are breastfeeding, are overweight, or have darker skin.

What are the benefits of taking vitamin D3?

With so many people susceptible to vitamin D3 deficiencies, a range of products and supplements are available on the market.

With this in mind, let’s explore some of the many benefits of taking vitamin D3 on a daily basis:

  • Insulin control: Vitamin D3 stimulates the pancreas and triggers the process that produces insulin.[5]
  • Heart disease: Research has shown that vitamin D3 can lower the chances of heart disease development.[6]
  • Flu: Studies have shown that healthy amounts of vitamin D3 can help in the fight against flu.[7]
  • Type 1 diabetes: One study found that regular vitamin D3 intake in infants reduced the risk of type 1 diabetes by 78%.[8]
  • Depression: It is thought that vitamin D3 may play a crucial role in combating depression.[9]
  • Weight loss: Studies have shown that vitamin D3 could have a pivotal role in weight loss.[10]

These are just some of the many claimed and studied benefits of taking vitamin D3 supplements, but there are many more, both explored, and still under study.

How much vitamin D3 should you take per day?

If you are worried about a vitamin D3 deficiency in your own body, as stated, there are supplements and vitamin products available on the market.

The only way to truly know whether you have a deficiency of vitamin D3 is by having a blood test, however.

In these tests, healthcare providers measure the storage form of the vitamin (calcifediol), and anything under 12 ng/ml is considered to be deficient.

The recommended daily allowance for a healthy and fully-grown adult is 600 IU (15 mcg). For adults over the age of 70, the recommended daily allowance is 800 IU (20 mcg). This also happens to be the same allowance for women who are pregnant or breastfeeding.

What is the difference between vitamin D and D3?

As you’re probably aware, there are different types of vitamin D, the most common of which are vitamin D2 and D3.

Originally, there was also vitamin D1, but after study, it was discovered to be a mixture of compounds, rather than a pure form of vitamin D.

As vitamins D2 and D3 are the most important to the human diet, here we shall discuss the differences between them.

Interestingly, the main difference between vitamin D2 and D3 is that vitamin D2 (ergocalciferol) is sourced from plants, while D3 is sourced from animals. As vitamin D2 is cheaper to produce, it is often found in fortified foods.

This does come at a trade-off, however, as research suggests that vitamin D2 is less effective at raising blood levels of vitamin D than vitamin D3.

What are the main sources of vitamin D3?

Aside from the vitamin D produced by exposure to sunlight, there are a great many sources of vitamin D3 in foods.

Some of the most popular and well-known sources include:

  •       Oily fish (such as tuna, mackerel, and salmon)
  •       Fish oil
  •       Liver
  •       Egg yolk
  •       Butter

Aside from the above-mentioned foods, vitamin D3 is often found in fitness supplements and nootropics. In fact, according to some health and fitness websites, like, vitamin D3, while not common, can sometimes be found as a natural fat burning and/or testosterone boosting ingredient.

The Importance of Vitamin D3

Vitamin D3 is an important part of a healthy lifestyle and offers a wide range of benefits, from bone maintenance, through to the prevention of diseases and poor mental health.

As vitamin D3 is primarily produced by the body when exposed to sunlight, this means that not everyone will have the desired levels of vitamin D3 in their body. The only way to find out whether a person has healthy levels of vitamin D3 is to take a blood test.

If you find that you are deficient in vitamin D3, you can increase your intake of certain foods, especially fish (such as tuna, salmon, and mackerel), or take specially designed supplements to help improve and sustain vitamin D3 levels.

Remember to try and get out and enjoy life in the sun, as vitamin D3 can go a long way in helping you enjoy a comfortable and healthy lifestyle.

Reading the Label on Your Multivitamins

The labels on multivitamins contain a variety of abbreviations based on Dietary Reference Intakes, or DRIs. These values are based on what a healthy person needs for each specific nutrient on a daily basis. Here are the three most common values you’ll see and what they mean.

  • RDA: RDA stands for Recommended Daily Allowance. This indicates the average amount of daily intake a healthy person needs of that specific nutrient to meet their nutritional needs.
  • AI: Adequate Intake is a value that’s used for a nutrient that doesn’t have enough scientific evidence to designate a specific RDA. The AI listed is set at a level that is assumed to be adequate for nutritional needs.
  • UL: UL indicates the Tolerable Upper Intake Level of the nutrient without causing adverse side effects.

The %Daily Value, or DV, listed on your multivitamin label is based on these three values. In simplest terms, it tells how much of each nutrient a serving of that particular multivitamin will contribute to your nutritional needs for the day.

Where to Buy Multivitamins

You can find multivitamins almost anywhere, even drug stores and grocery stores. However, you will usually find higher quality vitamins at health food stores and through independent supplement companies online. High-quality multivitamins are available over-the-counter, but doctors may also prescribe specific formulations at certain stages of life.

Why You Need to Take a Multivitamin Every Day

No matter how good your diet is, it’s very difficult to meet optimal nutrition levels each day through diet alone. Being chronically deficient in certain nutrients can take a major toll on your health. For example, the effects of prolonged calcium deficiency include osteoporosis and an increased risk of bone fractures as you age.

Potassium deficiency increases your risk of kidney stones and high blood pressure. Vitamin D deficiencies lead to inflammatory problems and a weakened immune system. And, finally, low iron intake causes anemia which can affect brain function, immune function, and more.

Other common nutrient deficiencies include magnesium, Vitamins A, C, and E, and choline. Taking a multivitamin everyday addresses these possible deficiencies. Although a multivitamin cannot make up for eating a poor diet, it can help to prevent deficiencies that could lead to serious health problems. It’s a simple step that can have a major impact on your health.

Incorporating Vitamins into Your Daily Routine

One of the first things you’ll notice when you begin comparing labels on multivitamins is that each manufacturer has their own recommendations for when to take them. There really isn’t one specific time that’s better than another, so you should do some experimenting to find what works best for you.

Some people do best when they take them with a meal to avoid an upset stomach. Others believe taking them on an empty stomach improves absorption. You could also split up the dose and take half in the morning and half in the evening.

You should keep in mind that certain nutrients, especially B vitamins, boost energy levels. That means they could keep you awake if you take them right before bed. Some vitamins can interact with or decrease the effectiveness of certain medications. Always consult with your doctor before you start taking them if you take medication.

Differences Between Multivitamins for Men, Women, and Kids

Although all humans need the same nutrients for optimal health, some vitamins and minerals are required in different amounts for men, women, and kids. Men require more zinc, magnesium, choline, and vitamin K than women do. Additionally, women’s nutritional requirements fluctuate at certain stages of life, such as during pregnancy and after menopause.

On the other hand, kids are more susceptible to negative side effects from mega doses of certain nutrients because of their small size. For these reasons, it’s best to choose a multivitamin that’s formulated for your age and gender.


As you can see, there are a lot of good reasons to take a multivitamin. There are literally hundreds of them to choose from, so it’s important to do your research and choose one that’s geared toward your individual needs. Don’t hesitate to consult with your doctor or with the manufacturer if you have questions or concerns.


[4] Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: National Academy Press, 2010.

About Shannon Clark

Shannon holds a degree in Exercise Science and is a certified personal trainer and fitness writer with over 10 years of industry experience.

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