Can nutrition improve athletic performance?


If you want to become faster, stronger, and more flexible, the food that you eat matters.

Optimal nutrition is the key to peak performance. Food provides essential nutrients necessary to build, repair and maintain a strong body.

Exercise adaptations are built on a sound training regimen and generally occur over a period of weeks.

Changes in diet can be implemented quickly and can have an immediate effect on how your body performs and repairs.

Evaluating specific biomarkers in your blood can help to identify nutritional inadequacies, which can explain why you may not be performing at your peak.

Some important nutrient biomarkers include:

Complete Blood Count (CBC) – A CBC gives important information about the kinds and numbers of cells in the blood, specifically red blood cells, white blood cells and platelets.


A CBC helps to identify causes of weakness, fatigue and bruising.  It also helps diagnose conditions such as anemia and infections, and can identify if oxygen transfer to muscles and other organs is compromised (e.g. low hemoglobin).

Many athletes who over-train have anemia and problems with their immune systems, such as recurrent infections.

A CBC can also identify potential vitamin B12 and folic acid deficiencies.

B12 can be low in those athletes who are vegetarian and don’t supplement. A deficiency in this vitamin can adversely affect energy and performance. B12 injections can be helpful for these patients.



Iron is essential for the immune system and energy. Low levels can also affect mood and heart rate. I like to measure iron by ferritin level, which is an indication of iron storage.

Iron is commonly low in female athletes and vegetarians. Supplementing with iron is only recommended for those with deficiencies or for menstruating women.

Iron rich foods include meat, dark leafy greens, nuts and beans.Heme sources of iron (i.e. from meat) is better absorbed than non-heme (from plants) iron.

Iron is best absorbed when taken in conjunction with a source of vitamin C (e.g. peppers, greens, broccoli, cauliflower, fruit).

Creatine kinase (CK) is a type of enzyme that is located in several tissues throughout the body, including muscle. In normal conditions, there is a small amount of creatine kinase circulating in the blood, but when muscle damage occurs, CK leaks from the damaged cells and the amount of CK in the blood can rise substantially. Blood levels of CK can act as an indicator of muscle damage and the extent to which you may be over-training.

To help repair muscle damage and reduce high levels of CK, it is helpful to increase consumption of protein (e.g. chicken, fish, grass-fed beef, eggs) and reassess your training practices.

Vitamin D and calcium – Low levels of each of these nutrients can increase the risk of low bone mineral density and stress fractures. Calcium plays an integral role in the growth, maintenance and repair of bone tissue, regulation of muscle contraction, nerve conduction, and normal blood clotting.

Vitamin D is essential for bone health because your body needs it to absorb calcium. It also regulates the development and maintenance of the nervous system and of skeletal muscle (among its many other important functions). Low levels of vitamin D are endemic in the Pacific Northwest. I often recommend patients have their levels checked.

Dairy products like yogurt and cheese, as well as leafy green vegetables and dried beans, are rich in calcium .

To increase your vitamin D level, either spend some time in the sun (5-30 minutes of exposure on arms, legs, back or face without sunscreen, depending on skin color, two times per week). If that’s not possible (as it’s often not where we live), eat more fatty fish (such as sardines, mackerel, and salmon), egg yolks, butter, beef liver, cheese, and fish oil.

Some foods, such as milk, yogurt, cereal, and orange juice are fortified with vitamin D, but it is ideal to eat whole foods that are natural sources whenever possible. Supplements are necessary if someone is found to have a vitamin D level (25(OH)D) of less than 30 ng/mL.

BUN (Blood Urea Nitrogen) and creatinine are indicators of kidney function. A blood urea nitrogen (BUN) test measures the amount of nitrogen in your blood that comes from the waste product urea. Urea is made when protein is broken down in your body. It is secreted out of your body through urine.

A BUN test is done to see how well your kidneys are working. If your kidneys are not able to remove urea from the blood normally, your BUN level rises. Heart failure, dehydration, or a diet too high in protein can also make your BUN level higher.

A BUN-to-creatinine ratio can help to identify dehydration.

BUN and creatinine can help determine if you need to increase your fluids as well as adjust protein intake, which is often consumed in excess by athletes due to misconceptions of optimal requirements.

The general protein recommendations for athletes range from 1- 1.8 g/kg body weight, depending on the type of activity. More is not better.




What does a healthy diet look like for an athlete?

The Basics:

Carbohydrates, proteins and fats provide the energy necessary to maintain body functions at rest and during activity.



Carbohydrates primarily come from vegetables, fruits, legumes and grains. Carbohydrates can be classified according to how they affect one’s blood sugar. A high glycemic carbohydrate (e.g. refined cereal, Gatorade) will lead to a rapid increase in blood sugar whereas a low glycemic carbohydrate (e.g. yogurt, legumes) has more of a stabilizing effect on blood sugar. Carbohydrates are responsible for energy, fat metabolism and sparing muscle protein. The types of carbohydrates an athlete should consume depends on the energy requirement of the sport (i.e. aerobic or anaerobic)

Protein is found both in animals, grains and plants. Animal proteins are classified as being “complete” and as such are optimal in terms of repair and recovery. Protein functions as part of our immune system, hormones and fuel when muscle glycogen (carbohydrate) is depleted. Protein is especially important for repair as well as stabilizing blood sugar levels.

Fats or lipids, are found in both and animals and plants. They are classified according to their chemical make-up or degree of saturation. Fat is the most energy dense nutrient. It is an ideal fuel source for lower intensity or endurance activities. Other functions include: nerve transmission, vitamin transport and organ cushioning. Research shows that optimum health can be achieved by a diet higher in omega 3 fats e.g. cold water fish and monounsaturated fats such as olive oil. I recommend using extra virgin olive oil for salad dressing and low heat cooking and walnut, almond or coconut oil for moderate heat cooking. Avoiding trans fats and partially hydrogenated oils is important for general health. In my observation, many popular snacks contain a combination of these unhealthy fats, along with sugar and artificial ingredients. These snacks are poor choices for recovery and repair and are major causes of obesity and other chronic health conditions.


In general, it is recommended that athletes consume approximately 55% carbohydrates, 30% fat and 15% protein of their total caloric intake.

General Recommendations to improve athletic performance

  • Emphasize whole foods (preferably local, seasonal and if possible organic)
  • Pre-exercise nutrition should be 4-6 hours before practice/game and should consist primarily of low glycemic sources. If a game is in the early morning, then dinner the prior night should meet these criteria. Pre-exercise nutrition is important for maximizing glycogen (carbohydrate) storage in muscle. An additional snack is recommended 30-60 minutes prior to the practice/game
  • Moderate-high glycemic foods should be consumed every 20 minutes during exercise to reduce muscle protein breakdown.
  • Moderate-high glycemic foods are also the foods of choice after exercise and should be consumed within 30 minutes after a practice/game in order to minimize muscle catabolism (breakdown) and maintain anabolic state. This helps to support recovery and immune function
  • A post exercise meal 1-2 hours after practice/game should consist primarily of low glycemic sources
  • Stay hydrated throughout the day and especially before/during/after games and practices. For activities under 90 minutes, water is the best choice. Vitamin drinks and other colorful concoctions are superfluous and can damage your teeth. Coconut water is a healthy option for electrolyte replacement and hydration
  • Take a multi-vitamin/mineral (with iron if you are anemic or menstruating)
  • Sleep 8-9 hours per night


For specific sports nutrition recommendations or to have you blood bio-markers assessed to identify why you may not be optimally performing, please contact my office for more information.

Dr. Lecovin and his wife Stephanie (a registered dietitian) are available for group lectures on sports nutrition and meal planning to improve athletic performance.

About the Author

Dr. Geoff LecovinNaturopathic Physician/Chiropractor/Acupuncturist/Certified Strength and Conditioning Specialist/Corrective Exercise Specialist/Performance Enhancement Specialist/Certified Sports Nutritionist/View all posts by Dr. Geoff Lecovin