Understanding Vitamins

Featured Image Vitamins

Vitamins are organic compounds that perform a number of functions in the body and support various metabolic processes such as hair growth, immunity, energy transfer, digestion, and repair. Vitamins are classified as “micronutrients” (just like minerals) and are substances we all need to live and achieve optimal health, immunity, and basic functioning. That said, there’s no one-diet-fits-all approach when it comes to a fitness client’s micronutrient needs.

Here’s what you need to know and what to look for when providing nutritional guidance (that is within your scope) to your clients.

Types of Vitamins

Vitamins, aside from being categorized as micronutrients – meaning we need them in trace amounts (as opposed to macronutrients), are further divided into water-soluble and fat-soluble.

Water-soluble vitamins include vitamin C and the large group of B vitamins. These vitamins are dissolved in water and are absorbed both passively and actively in the body via membranes in the GI tract. These vitamins are not readily stored (like fat-soluble vitamins). This means, we need to consume these types of vitamins more often.

Fat-soluble vitamins include vitamins A, D, E, and K.  These vitamins, unlike their water-soluble counterparts, are mostly absorbed passively in the GI tract. They are bound to dietary fat, which underscores why the consumption of healthy dietary fat is necessary to transport these nutrients. Fat-soluble vitamins are also stored in fatty tissues in the body – this means they can build up in toxicity if an individual consumes too much of any one of them. Vitamin D is an interesting one that can be obtained not only from diet, but from sun exposure.

Factors that Impact Absorption of Vitamins

There are several factors that impact the absorption, digestion, and overall consumption of vitamins. For example, some micronutrients lose their potency through various cooking processes. Those types of nutrients are better absorbed when eaten in their raw state. Also, other micronutrients are best absorbed when they are consumed with other foods or when their structure is broken down first (via crushing or cutting).

Here’s one practical example. Tomatoes contain a substance called lycopene. The body can be more readily absorb this nutrient when tomatoes are consumed in a cooked fashion as opposed to eating them raw. The same is true for many of the carotenoids that you find in yellow, orange, or red plants, like peppers for instance.

However, a basic rule one can adhere to is that water-soluble vitamins are more readily absorbed from raw foods, and fat-soluble vitamins are best consumed from cooked foods. Bear in mind, some foods are high in both types of vitamins, so it may behoove us all to enjoy a mixture of fresh salads and roasted vegetables. Many folks believe eating seasonally for the weather will feed the body appropriately: summer is better for raw, while winter is better for cooked.


Fitness Nutrition Coach


The biggest points to remember when thinking about vitamins are the following:

  1. No single diet is best for every person
  2. Keep the big picture in mind
  3. Not every individual needs the exact same amount of vitamins
  4. Vitamin requirements are influenced by various factors such as biological sex, age, medication use, activity levels, stress, injury, pregnancy (or menstruation), energy intake, or illness.

Nutrition, including vitamin consumption, is highly personalized. This is the take-home message. Like exercise, too much of a vitamin, or not enough of one, can result in various health problems that our clients should be aware of. Our next blog will review the major vitamins, and how their respective excesses and deficiencies can impact health outcomes.


 Beradi, J., Andres, R., St. Pierre, B., Scott-Dixon, K., Kollias, H., DePutter, C. (2018). The Essentials of Sport and Exercise Nutrition, 3rd Edition.


Dr. Erin Nitschke, NFPT-CPT, NSCA-CPT, ACE Health Coach, Fitness Nutrition Specialist, Therapeutic Exercise Specialist, and Pn1 is a health and human performance college professor, fitness blogger, mother, and passionate fitness professional. She has over 15 years of experience in the fitness industry and college instruction. Erin believes in the power of a holistic approach to healthy living. She loves encouraging her clients and students to develop body harmony by teaching focused skill development and lifestyle balance. Erin is also the Director of Educational Partnerships & Programs for the NFPT. Erin is an editorial author for ACE, IDEA, The Sheridan Press, and the Casper Star Tribune. Visit her personal blog at belivestaywell.com