Which vitamins do I need? Everything you need to know about intake, functions, and how much you need

Without vitamins, your body simply can’t function properly. You might not notice it right away, but a lack of essential micronutrients can affect your energy levels, immune system, recovery, skin, sleep—and even your mood. And that’s not even counting your athletic performance.

Time to take a closer look at this nutritional foundation. What exactly are vitamins? How many are there? Which ones do you really need? And how are they absorbed in your body?

In a nutshell

Vitamins are essential to your health. There are 13 you need to get from food or supplements. Some are fat-soluble, others water-soluble—and that affects how your body absorbs them. Want to know how this works, which vitamins you need daily, and what they do for you? Keep reading!

What are vitamins?

Vitamins are organic compounds your body needs in small amounts to function properly. They don’t provide energy like carbs, proteins, or fats, but they’re critical for key processes, such as:

• Cell function
• Immune defense
• Bone health
• Oxygen transport
• Mood and mental performance

Most vitamins can’t be made—or not in sufficient amounts—by your body. That means you have to get them from your diet. If you eat a limited range of foods, experience stress, follow a strict diet, or deal with digestive issues, you’re more likely to develop deficiencies.

How many vitamins are there?

There are 13 essential vitamins your body needs to stay healthy. “Essential” means you must get them through food or supplements because your body can’t (fully) produce them on its own.

They fall into two main categories:

Fat-soluble vitamins

• Vitamin A
• Vitamin D
• Vitamin E
• Vitamin K

Water-soluble vitamins

• Vitamin C
• The eight B vitamins (B1 through B12)

Together, the B vitamins form the B-complex, though each one has a distinct role in your body.

What do vitamins do?

Think of vitamins as small but mighty switches that keep your body running. Without them, your energy production slows down, your immune system weakens, and you just don’t feel like yourself.

Here’s what each type of vitamin can do for you:

• Vitamin A – The beauty booster for your skin and eyes, and a champion for your immune system. Found in liver, carrots, and dark leafy greens.
• B-complex vitamins – Your personal energy managers. They support energy production, nerve function, and mental clarity. Found in whole grains, meat, eggs, and nuts.
• Vitamin C – An antioxidant powerhouse. It supports immunity and improves iron absorption. Think citrus fruits, kiwi, and bell peppers.
• Vitamin D – Crucial for strong bones and immunity. Since sunshine isn’t always guaranteed, especially in Northern climates, many people supplement it.
• Vitamin E – The bodyguard for your cells, thanks to its antioxidant strength. Found in nuts, seeds, and plant-based oils.
• Vitamin K – Keeps your blood clotting and bones healthy. Found mainly in green vegetables.

Fat-soluble vs. water-soluble: What’s the difference?

Fat-soluble vitamins (A, D, E, K)

• Absorbed in the small intestine along with dietary fats
• Stored in the liver and body fat
• Don’t need to be consumed daily, but excess amounts from supplements can pose a risk

Overview:

• Vitamin A – Supports eyes, skin, and immune function
• Vitamin D – Regulates calcium levels, key for strong bones and mood
• Vitamin E – Protects your cells as an antioxidant
• Vitamin K – Important for blood clotting and bone strength

Water-soluble vitamins (B-complex & C)

• Not stored in large amounts
• Excess is flushed out through urine
• Need to be replenished daily through diet or supplements

B-complex roles:

• B1 (Thiamine): Energy metabolism & nerve function
• B2 (Riboflavin): Energy production & skin health
• B3 (Niacin): Releases energy and supports skin
• B5 (Pantothenic acid): Hormone production & fat metabolism
• B6 (Pyridoxine): Protein metabolism & hormone regulation
• B8 (Biotin): Maintains healthy hair and skin
• B9 (Folic acid): Key during pregnancy for fetal development
• B12 (Cobalamin): Essential for nerves and red blood cell production

How are vitamins absorbed?

Vitamin absorption starts in the gastrointestinal tract.

• Water-soluble vitamins dissolve in fluid, are absorbed in the small intestine, travel
  through your bloodstream, and any excess is excreted in urine.
• Fat-soluble vitamins bind to fats in your diet and are absorbed via the lymphatic
  system.

Tip: To get the most out of fat-soluble vitamins like A or D, always take them with a source of healthy fats—such as a vitamin D supplement alongside a meal containing nuts or oily fish.

How much do you need per day?

The recommended daily intake (RDI) varies per vitamin and per individual. Factors such as age, gender, lifestyle, diet, pregnancy, and health status all play a role.

Examples:

• Vitamin C: Around 75 mg for adults—but smokers may need more
• Vitamin D: About 10 micrograms per day—yet many people benefit from supplements, especially in winter

Organizations like the EFSA and national nutrition centers provide guidelines. But above all, listen to your body. Low energy, poor recovery, or a limited diet may be signs that supplementation could help—ideally discussed with a healthcare professional.

How to get enough vitamins

The key is a varied and balanced diet. Focus on:

• Fresh vegetables and fruit
• Whole grains
• Nuts, seeds, eggs, and fish

Supplements are not a substitute for healthy food, but they can be a helpful addition—especially for:

• Vitamin D in darker months
• Vitamin B12 if you eat plant-based
• Higher needs due to stress, sports, or recovery

Also, consider how you take your vitamins

• Fat-soluble ones like A, D, E, and K should be taken with some dietary fat
• Water-soluble ones should be taken daily

And always pay attention to your body: fatigue, dull skin, poor sleep, or muscle twitches may point to a deficiency. In that case, you might also want to check your protein intake—vitamins don’t work in isolation.

Vitamins fuel your body from within

You don’t have to be a health fanatic to take vitamins seriously. Start with the basics: eat well, stay aware, and know what your body needs. If you have specific goals or notice signs of deficiency, the right supplement can make a big difference.

Health doesn’t start with perfection—it starts with awareness.