Assessing Yourself for Malnutrition When Thru-Hiking

Failure to Meet Increased Daily Energy Demands

With consideration to thru-hiking and malnutrition, we’re mostly focused on the energy imbalance created from not taking in as much energy as the body needs, to pull off the enduring work of the hiking venture. The below table provides the six pillars of malnutrition exclusively from environmental circumstances (does not apply to malnutrition from injury, or acute or chronic illness, or inflammatory conditions) based on the American Society for Parenteral and Enteral Nutrition and the Academy of Nutrition and Diatetic’s Characteristics Recommended for the Identification and Documentation of Adult Malnutrition. In order for a diagnosis of malnutrition to occur, two of the six conditions must be met:

Condition	Moderate	Severe
Reduced Energy Intake	<75% of estimated requirements over 3 or more months	<51% of estimated requirements for 1 or more months
Weight Loss	5% loss over 1 month; 7.5% loss over 3 months	over 5% loss over 1 month; over 7.5% loss over 3 months
Subcutaneous Fat Loss (around the eyes, in the tricep region, fat over the ribs)	Mild	Severe
Muscle Mass Loss (temples muscles, pecs and deltoid muscles, muscles on the back of the hand before the main knuckles, muscles of upper back between the shoulders, or even thighs and calves)	Mild	Severe
Fluid Accumulation (arms or legs, scrotum or vulva, in the abdomen)	Mild	Severe
Reduced Grip Strength	May not be noticeable	Reduced

6 Clinical Features Involved in Malnutrition (2 must be present for a diagnosis of malnutrition)

Failure to take in enough energy to meet the increased daily requirements of this type of dedicated hiking is of utmost concern. The hiker should have a good estimate of what their daily needs will be to avoid under eating.

I have a day hiking calculator that provides an estimate of total daily energy needs and calories burned on the trail, based on minutes spent on different trail conditions. You can try to game the calculator for thru-hiking by adding your pack’s weight to your weight in the appropriate input field, or just use the calculator as intended, then add a few hundred kcal to the end result to take into account the extra burden of the pack. That might get you a ballpark idea, but keep in mind I haven’t back tested the calculator for thru-hiking, so proceed at your own risk.

You should also know you daily protein requirements, which are significantly increased in a thru-hiking venture. Read my article on protein requirements for hiking to get an understanding on how to calculate your needs for this macronutrient, based on the International Society of Sports Nutrition recommendations. Again, similar to my calculator, the discussion of whole food intake of protein is based on day-hiking (i.e. stuff you probably aren’t going to carry on a thru-hike), but the numbers and calculations still apply.

Signs of Vitamin Deficiencies for Thru-Hiking

In a lot of cases, when daily energy needs rise as they do when you go on a long haul, so do daily vitamin intake requirements. Further, in hotter environments, several water soluble vitamins can get flushed out with sweat, especially for those hikers not yet acclimated to the heat (see my article, Sweat, Mineral, and Micronutrient Losses Related to Hiking in Higher Temperatures). I’m adding higher probability vitamin deficiencies to this table, regarding thru-hiking, based solely on the idea that these can manifest in a relatively short period of time after reduced intake or accelerated elimination. Of everything on the table, I’d be firstly concerned about vitamin C, as not only can it be sweated out, but the process of sweating is dependent upon it.

Vitamin	Time to Symptoms of Deficiency After Inadequate Intake	Common Symptoms
Vitamin C	8 to 12 weeks	starts with irritability & anorexia, then progresses: poor wound healing, gum swelling, small dots of bleeding under mucous membranes in mouth, or on skin around hair follicles, bruised splotches on skin
Thiamine – Vitamin B1	3 to 4 weeks	starts with irritability & anorexia (from nausea/vomiting) & short term memory difficulties, then progresses: loss of sensation in hands/feet/arms/legs, or feeling of tingling ‘pins and needles’, and loss of arm/leg reflexes, calf pain and leg weakness, involuntary side to side eye muscle tremor, fever, abnormal gait, and eventually, progressively worsening thinking impairment, and heart failure.
Niacin – Vitamin B3	2 to 9 months	pellagra – starts with diarrhea, then progresses to sun sensitive dermatitis, then further progresses to cognitive impairment, then death
Folic Acid – Vitamin B9	8 to 16 weeks	starts with headache, dizziness, shortness of breath, pale skin; other symptoms include nausea/vomiting, diarrhea, weight loss, tiredness, fatigue and lethargy,

Possible Vitamin Deficiencies To Look For When Thru-Hiking

Low Probability Vitamin Deficiencies When Thru-hiking

There are some vitamins whose onset of deficiency symptoms takes so long to present, after a dietary disruption of a healthy nourished adult, that such is not applicable to thru-hiking related deficiency for most hikers. However there are some long-haulers that can stay out on the Appalachian Trail, or equivalent, for over half a year, so I’ll provide a little info below, in terms of time to onset of symptoms:

Riboflavin – B2: It takes past 9 months of Riboflavin cessation to induce a laboratory observation of deficiency, and a longer period of time to induce signs and symptoms.
Pyridoxine – B6: Based on washout studies, B6 levels in the blood can fall below normal range in 3-6 weeks after a restrictive diet, as it has a half life of around 1 month. However, B6 levels in the muscle, where most of the body’s store of the vitamin exists, stay relatively unchanged during this period.
Cyanocobalamin – B12: It can take several years for a B12 deficiency to present, as the body has such a vast store. Thus for the healthy thru-hiker, this one is irrelevant.
Biotin: It can take several months to develop a biotin deficiency. In one case study of a patient needing IV nutrition, because a large portion of their intestine had been surgically removed, it took 6 months to develop biotin deficiency. So the chance of developing this deficiency on the trail seems small, and would have to occur under extreme conditions, like a hiker taking anticonvulsants or oral contraceptives, who experiences months of trail related diarrhea, in which the gut bacteria, responsible for some internal biotin synthesis, is severely disrupted. Or perhaps a vegan hiker, with gut bacteria disrupting chronic diarrhea, that doesn’t have access to a daily vitamin.
Vitamin A: It takes 4 months for an adult with normal vitamin A stores in the liver to develop clinical symptoms of a deficiency after removing such from the diet, based on its EAR. Vitamin A’s Estimated Average Requirement (EAR) is the “estimated daily intake required to meet physiologic needs and maintain “minimal acceptable liver reserves”, which are estimated to be 0.07 μmol (20 μg) vitamin A (retinol)/g liver. This concentration is assumed to prevent clinical signs of deficiency, maintain adequate plasma vitamin A concentrations, allow biliary excretion of vitamin A, and protect an individual consuming a vitamin A–deficient diet against clinical signs of deficiency for 4 months”.
Chromium: It takes 3 years to develop a chromium deficiency based on 3 case studies of patients reliant on long term parenteral nutrition. In another study, subjects being fed a chromium poor diet for 14 weeks did show marginal increases in blood glucose, but such was only low single digit increases (mg/dL) at fasting and after eating, and not clinically significant (still within normal range).
Pantothenic Acid: This one is pretty ubiquitous in plant and animal foods. Pack some tuna and sunflower seeds and your good. The only way you’re going to get a pantothenic acid deficiency is if you are so severely malnourished that you shouldn’t/couldn’t be hiking.

Examine Yourself Head To Toe

Some of these you may need a mirror, a selfie camera on a phone, or hiking buddy to help you with.

Weight Loss

I went over the numbers in the energy demands failure section above. Definitely look for loss of muscle and subcutaneous fat; especially in the temples and the neck, as it’s just easy to see in those spots. Look for muscle loss on the back of your hands. Also, does your shoulder look thin and square shaped from you deltoid being wasted? Are your ribs sticking out more from loss of fat?

Loss of Strength

Lower extremity (read leg) weakness could indicate a Thiamine B1 deficiency.

Fluid Accumulation

As previously stated, we’re looking for fluid in the arms or legs, scrotum or vulva, and/or in the abdomen. This could mean a loss of blood proteins from lack of energy/protein intake, or a Thiamine B1 deficiency.

Hair Exam

Hair Loss = protein, B12, or Folic Acid deficiency
Brittle Hair = biotin deficiency
Change in Hair Color = zinc deficiency
Dry Hair = vitamin A and/or E deficiency
Hair That’s Easily Plucked Out = protein and/or biotin and/or zinc related deficiency
Hair That Has a Corkscrew Appearance = vitamin A and/or C

Skin Exam

Peeling Skin = riboflavin deficiency
Tiny, Unraised, Round Red Bleeding Spots on Skin = vitamin A and/or C deficiency
Hair Follicle Bleeding Spots on Skin = vitamin C
Super Dry, Scaly, Itchy Skin That Has Bran-like Peeling = essential fatty acid
Bruising From Bleeding Underneath Skin = vitamin C and/or K
Unusual Pigmentation, with Cracked and Crusting Skin = niacin deficiency
Dry, Goose Bump-like, Acne-like Skin = Vitamin A
Red, Blister-like Clusters Near Mouth, Nose Openings = zinc deficiency
Poor Wound Healing = vitamin A and/or C and/or zinc and/or iron deficiency

Eye Exam

Abnormal Spots on Whites of Eyes = vitamin A deficiency
Dry, Scaly White Part of Eye = vitamin A deficiency
Redness/Inflammation in Outer Corners of Eyes = riboflavin deficiency
Night Blindness = vitamin A deficiency

Mouth and Lips Exam

Redness/Inflammation/Cracks in Outer Corners of Lips = B complex and/or iron and/or protein deficiency
Swollen, Inflamed Tongue = niacin and/or folic acid and/or vitamin B12
Magenta, Vampire-like Tongue = riboflavin deficiency
Gum Bleeding and Inflamed with Loose Teeth = vitamin C deficiency

Hands & Arms, Feet & Legs Exam

Joint Pain = vitamin C deficiency
Calf Pain and Leg Weakness = B1 deficiency

Mental Status/Nervous System Exam

Drooping Eyelids and Weak/Paralyzed Eye Muscles That Keep Eye Movement From Syncing Like Normal = B1 deficiency
Tingling Feeling in Hands/Arms, Feet/Legs = B1 and/or B12 and/or biotin deficiency
Decreased Ability to Feel Vibration and Body Position = B12 deficiency
Anxiety/Depression/Hallucination Together = niacin deficiency
Memory Problems = B12 deficiency
Loss of Leg Deep Tendon Reflex = B1 and/or B12 deficiency

Disclaimer: Nothing in this article should be construed as medical advice; only you, your doctor, and nutritionist can give you personally crafted medical advice.

References

Observations on Induced Riboflavin Deficiency and the Riboflavin Requirement of Man; The Journal of Nutrition, Volume 25, Issue 4, April 1943, Pages 361–377

Effects of Dietary Depletion of Riboflavin: One Figure; The Journal of Nutrition, Volume 39, Issue 3, November 1949, Pages 357–373

Dietary Reference Values for vitamin B6

Response of vitamin B-6 content of muscle to changes in vitamin B-6 intake in men; The American Journal of Clinical Nutrition, Volume 53, Issue 6, June 1991, Pages 1436–1442

Biotin and Other Interferences in Immunoassays and Biotin Deficiency Science Direct magazine style page

Biotin Deficiency Symptoms and Causes

Isoniazid-associated pellagra during mass scale-up of tuberculosis preventive therapy: a case-control study; The Lancet Global Health, May, 2022

Dermatologic Manifestations of Pellagra, Medscape.com

Folate Deficiency

Folate Deficiency Clinical Presentation

Vitamin A isotope dilution predicts liver stores in line with long-term vitamin A intake above the current Recommended Dietary Allowance for young adult women, Am J Clin Nutr. 2013 Nov; 98(5): 1192–1199

Storage of vitamins and minerals – Hepatitis C Trust

Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc, Institute of Medicine (US) Panel on Micronutrients. Washington (DC): National Academies Press (US); 2001

Effects of exercise on chromium levels. Is supplementation required?, Sports Med 1997 Jun;23(6):341-9

Pantothenic Acid Fact Sheet for Health Professionals – NIH

Zinc Deficiency and Clinical Practice; JMAJ, August 2004—Vol. 47, No. 8 359; Journal of the Japan Medical Association (Vol. 129, No. 5, 2003, pages 613–616).