Nutrition strategies from recent firefighter work studies go far beyond “an apple a day”

If you’ve spent a couple seasons on the fireline, it's probably happened to you: a sore throat after working a long shift; fatigue that doesn't improve with rest; a cold or similar virus that stays long after the incident has terminated. For many wildland firefighters, such symptoms are simply part of the job. But do they have to be?

A few years ago, the U.S. Forest Service Missoula (Mont.) Technology and Development Center (MTDC) conducted a number of studies addressing wildland firefighter health and safety. Its final report gave wildland firefighters and their supervisors information for preventing injuries and illness — and maybe even death — on the fireground.

Between 30 and 50 percent of personnel visits to first-aid stations in fire camps each season are for upper respiratory problems, including coughs, colds and sore throats. The MTDC study identifies a number of factors that influence those symptoms: fatigue, exhaustion, stress, inadequate energy and nutrition, dehydration, smoke inhalation and sleep deprivation. But the study did not stop there. Researchers obtained skin tests, blood tests and salivary immunoglobulin tests to further illuminate why wildland firefighters experience a high rate of upper respiratory problems, and whether such problems can be prevented.

The Secret’s in the Saliva
The secretory immune system of the upper respiratory tract’s mucosal tissues is considered the body’s first line of defense against pathogens. Salivary immunoglobulin A (sIgA) inhibits attachment and replication of pathogens, preventing their entry into the body. Numerous studies have shown that sIgA decreases significantly after prolonged, intense physical effort. When sIgA values remain low, the body experiences a period of decreased immunity during which viruses and bacteria can gain a foothold.

One of the more significant studies proving the relationship between low sIgA values and poor immunity involved marathon runners. Researchers found that as many as 25 percent of the runners experienced an upper respiratory tract infection within two weeks of running a marathon. After longer races, more than 50 percent experienced similar infections.

Noting the similarity in physical output between marathoners and wildland firefighters (particularly hotshot crews), MTDC researchers carried out similar studies on the fireground — and produced some dramatic results. The researchers took saliva samples from hotshot crews just prior to and immediately after a 14-hour shift, as well as before their shift the following day. The firefighters’ sIgA values fell from 76.9 picograms (pg) per minute before the shift to 14 pg/min after the shift, but the values recovered by the start of the next shift. When firefighters worked a 24-hour shift, however, their immune response did not recover as well the following morning; in fact, their sIgA levels stayed low for five additional days of work.

Testing Fatigue
In conjunction with the salivary testing, researchers conducted several fatigue studies. They recorded firefighters’ heart rates before and after the tested work periods and found a direct correlation: When fatigue levels rose, immune system function fell. The greater the fatigue level, the lower the immune system level. Together, these studies reveal three concepts about fatigue and immunity:

• While initially depleted, the immune systems of wildland firefighters are able to recover after shifts with moderate energy expenditure;
• After longer and more difficult shifts, however, firefighters’ immune systems are unable to recover; and
• Immune function progressively declines with consecutive days of hard work.

Throughout the study, the fatigue index was inversely related to immune function.

Boosting Immunity
The researchers’ next question was obvious: How could wildland firefighters apply the results of the studies to reduce the long-term stress on their immune systems? Knowing that rest was a key factor in immune response, they decided to explore ways to use nutrition to create better work-recovery rates.

When the researchers investigated the effects of carbohydrate supplementation on work output, fatigue and immune function in wildland firefighters, they concluded that carbohydrate supplementation improves blood glucose levels, increases energy expenditure and work rate and reduces fatigue, especially later in a work shift. The sIgA levels of firefighters who received supplemental carbohydrates fell significantly less and recovered better after work shifts. In effect, the carbohydrate supplements provide energy for working muscles, the brain and the nervous system.

Study Recommendations
The immunity and fatigue studies produced several recommendations for maintaining your immune system during fire season:

• Establish good sleep habits to help ensure you’re well rested before deployment. Sleep deprivation compromises immune function.
• When you’re on the line, get seven to eight hours of sleep each night. How many times have you hung out and chatted with other crew members until the wee hours of the night, only to get up before dawn to start the next day? Then you wonder why you get sick a few days into the fire. Now you know!
• Use short (less than 20 minutes) and long (more than 90 minutes) naps whenever possible.
• Avoid excessive exposure to smoke.
• Consider taking days off the line when you experience upper respiratory symptoms “below the neck” (fever, deep cough, muscle aches, nausea and diarrhea).

PHOTO KIRK KEOGH Eating regular, balanced meals — both on and off the fireline — can significantly improve your immunity.

In addition, the studies led to the following recommendations for firefighters’ eating habits both before and during deployment:

• Eat regular meals, and use liquid and solid carbohydrate supplements. Suggested solid carbohydrates include beans, corn, rice, potatoes, whole grain breads and pasta.
• Eat at least two to four servings of fruits and three to five servings of vegetables daily (more when you’re on the fireline).
• Keep your fat intake low, because high-fat diets suppress immune function. No more than one-third of the fats you consume should be saturated and/or hydrogenated fats.
• During periods of weight loss or when you can’t get the recommended servings of fruits and vegetables, take a daily vitamin and mineral supplement.
• Stay hydrated. Firefighters need one liter of fluid for each hour of work. Drink before, during and after work. Use carbohydrate and electrolyte drinks (energy drinks) for one-third to one-half of your fluid needs (the balance should be supplied by water). For a list of energy drinks tested in the study, see the sidebar on p. 17.
• Consume one-third to one-half of an energy bar or candy bar during each hour of hard work. For a list of energy bars tested in the study, see the sidebar on p. 17.

Put Nutrition to Work
It’s time we take a closer look at how nutrition affects our well-being in the field. Simple strategies such as getting more rest (when given the opportunity) and ensuring adequate carbohydrate intake (liquid and solid) will offer us a better chance of good health and a safer fire season.

For further information regarding these studies go to www.fs.fed.us/eng/t-d.php?link=pubs, then go to the Safety and Health link and search for Report 8 (publication #0451 2802).

Dennis Childress has been with the fire service for more than 30 years and currently serves with the Orange County (Calif.) Fire Authority. A lecturer, author and instructor, he sits on the executive board of the Southern California Fire Training Officer’s Association and also represents the California Fire Service on NFPA 1500 and 1561.