Why Do We Need Vitamins & Minerals?

Do you take a multivitamin?

If you do, do you know why you take it?

Vitamins and minerals serve so many purposes for everyday living and athletic performance.

In this post, we take a look at two unique individuals:

  • An active older woman
  • A teenage basketball player
  • Myself!

These are case studies from Sports Nutrition for Health Professionals (2nd. Ed.) as I work through further educating myself about nutrition.

Becoming a Fitness Nutrition Specialist will help you develop expertise in all areas of nutrition education and promotion that are within the scope of practice for health and fitness professionals.

Case 1: Adele, The Active Octogenarian

Adele is an 85-year-old woman who is relatively new to physical activity. After her husband died last year she committed to a fitness program to help her maintain her independence. She participates in water fitness classes five days per week, trains with a personal trainer 2 hours per week, and attends yoga for one hour to days per week.

Adele tells you that her doctor told her that she is at risk for calcium and vitamin D deficiency and that she should make sure to get recommended amounts of the nutrients.

Explain the importance of calcium and vitamin D for older adults.

Why Is Calcium So Important?

Calcium is beneficial for older adults because it helps maintain strong bones and teeth. Those are the two areas in which calcium is mostly found in the body. Calcium has a number of other positive functions related to muscles, nerves, and blood vessels.

What Does Vitamin D Do?

Vitamin D also contributes to strong bones because it helps the body absorb calcium. The vitamin is known to help move muscles, helping to carry out vital functions within the nerves and the immune system in staving off bacteria and viruses. 

What are the recommended calcium and vitamin D intakes for Adele? Make a list of foods that she could consume to meet these daily needs.

Recommended IntakeFoods
Calcium1,200 mgDark green leafy vegetablesMilk, yogurt, cheeseSardinesMost grains
Vitamin D75 mgCitric fruits and vegetablesFatty fishOrgan meats

Adele could meet her Vitamin D needs through food intake, sunlight, or supplementation. What are the risks and benefits of each of these options?

Risks Benefits
Food IntakeVitamin D from fortified milk is poorly absorbed Eating whole, nutrient-dense foods
Sunlight Skin cancerNo supplementation needed
SupplementationPriceLack of regulationOveruse Ease of consumption

How would Adele know if she has a calcium or vitamin D deficiency?

Calcium Deficiency

At 85, Adele should be concerned about not getting enough calcium. Women older than 50 years are among the groups of people who don’t get enough calcium. 

Plus, “postmenopausal women because they experience greater bone loss and do not absorb calcium as well,” says the National Institutes of Health. “Sufficient calcium intake from food, and supplements if needed, can slow the rate of bone loss.”

Vitamin D Deficiency

The NIH is very specific when it comes to a vitamin D deficiency: Get a blood test. “In general, levels below 30 nmol/L (12 ng/mL) are too low for bone or overall health.”

Adele also shares with you that most of her friends get vitamin B12 shots to prevent or treat vitamin B12 deficiency. She tells you that she prefers not to take a supplement but she is concerned about getting enough of the vitamin because she heard that low levels are “bad news.”

Vitamin B12 Deficiency

What are the symptoms of vitamin B12 deficiency? How long does it take for the symptoms to develop?

Vitamin B12 (cobalamin) is important to us because it:

  • Keeps our nerve and blood cells healthy
  • Makes DNA. 

Many older adults struggle to absorb vitamin B12 because of their decreased food intake. Not being able to could result in many possible conditions, such as:

  • Tiredness and weakness
  • Balance issues
  • Depression
  • Confusion
  • Plus more.

What is the recommended level of vitamin B12 intake for Adele?

Adults are recommended 2.4 micrograms of vitamin B12.

What is the rationale behind vitamin B12 shots for older adults?

Shots are a way to supplement vitamin B12 intake. 

Make a list of foods that are high in vitamin B12. 

  • Liver & kidney
  • Milk
  • Eggs
  • Fish
  • Cheese
  • Muscle meats
  • Fortified breakfast cereals

Case 2: Brian, the High School Basketball Player

Brian is a 15-year-old high school basketball player. He is 6’2” and 180 lb. He tells you his mom has been telling him that he needs to eat better.

Appreciating that teens do not always consume a balanced diet, you decide to look up what is considered to be the “typical” teenage diet. You learn that the typical teen diet is characterized by an abundance of sweetened beverages, French fries, pizza, and fast food. It typically lacks adequate fruits, vegetables, low-fat dairy products, whole grains, lean meats, and fish. This makes for a diet very high in fat, saturated fat, trans fat, and added sugar too low in calcium; iron; zinc; potassium; vitamins A, D, and C; and folic acid. 

You are not surprised to find that Brian is no exception. When you ask him what kinds of foods he typically eats, he tells you that he knows that he has an overall lousy diet but that he is motivated to eat better because he knows it will help improve his basketball game. 

You are especially concerned about Brian’s micronutrient intake.

Fill in the following table. What “superfoods” are good sources of more than one of the micronutrients? 

NutrientRecommended Intake for Brian Good Food Sources Appropriate For Client
Calcium1,300 mg(Same as Adele)
Iron11 mgLean meat, poultry, fish, dried beans, veggies
Zinc11 mgLean meats, eggs, whole grains
Potassium3,000 mgFruits, veggies, milk, yogurt
Vitamin A900 mcg RAE Leafy greens, fortified breakfast cereals, fruits
Vitamin D15 mcg(Same as Adele)
Vitamin C75 mgCitrus fruits
Folic Acid400 mcg DFEVeggies, fruits, nuts, beans, peas, fortified breakfast cereals

Brian asks you how eating a more balanced diet with sufficient amounts of the nutrients listed in the table might affect his athletic performance. For each of the nutrients listed in the following table, briefly summarize the nutrients importance as it relates to exercise. 

NutrientRole In Exercise
CalciumSupports strong bones and muscle movement for weight-bearing and resistance exercises
IronDelivers oxygen to working muscles
ZincAssists in healing wounds and bolsters immune system
PotassiumAssists in blood pressure regulation and supports bone calcium
Vitamin ASupports vision and helps organs properly function
Vitamin DMoves muscles 
Vitamin CHelps protect cells from damaging effects of free radicals developed during digestion
Folic AcidMetabolizes amino acids

Train Yourself

Meeting Nutritional Needs

Based on your gender, age, activity level, and dietary habits, for which micronutrients do you think that you may not meet recommended intakes? For the nutrients you listed, what are the recommended daily intakes for you?

I’m a 31-year-old male who works out, on average, five days a week. 

I track my food with MyFitnessPal. The app doesn’t track all micronutrients, but here’s what it does track:

MicronutrientMy IntakeRecommended Daily Intake For My Age & Gender
Sodium996 mg2,300 mg (this is the max recommended amount)
Potassium2,397 mg3,400 mg
Vitamin A59%900 mcg RAE
Vitamin C137%90 mg
Calcium219%1,000 mg
Iron75%8 mg

Plan a one-day menu for yourself that would include the recommended amounts of the nutrients you posted above.

I won’t create a full menu here, but here are some foods to increase potassium and iron (vitamin C was covered earlier):


  • Fruit
  • Milk
  • Yogurt 
  • Lentils
  • Kidney beans


  • Lean meat, poultry, fish
  • Nuts and some dried fruits
  • Iron-fortified breakfast cereals and breads

Cooking for Optimal Nutrition

Consider how you select, store, and prepare fruits and vegetables. How could you select, store, and prepare fruits and vegetables differently to optimize the amount of micronutrients you consume? 

I often get frozen mixed veggies and berries, and pull them out of the freezer when I’m ready to use them. That has been a strategy that’s worked very well for me. 

I’m also able to get to a store every few days to buy fruits and veggies that are on sale. 

Photo by William Felker on Unsplash