Have you seen the movie The Martian? I highly recommend it. The premise is that an astronaut called Mark Watney goes with a team to Mars, gets left behind and has to survive.
I love semi-disaster stories and even better when it's Matt Damon playing the main character. Now, according to the book, Watney had lots of vitamins and mineral supplements to supplement his diet. But if he hadn't had those supplements, there are certain elements that he could have become deficient in that could have led to severe health problems.
Let's explore some of the metal elements - nutritional elements - that you might want to take with you if you were on a mission to Mars.
I think that most people will be surprised to learn that copper is so critical to our body systems. It is especially important in the company of iron and zinc. Many health care providers understand that if you use zinc you should use copper, but don’t truly understand why. Zinc will upregulate the synthesis of a copper binding ligand which indirectly antagonizes the absorption of copper in the GI tract. As a result, more copper is bound in the mucosal cells and prevented from entering circulation.
There was a fun case (not fun for the patient though) of a woman who was using a zinc- containing dental adhesive (>2 tubes per week) for her dentures, which caused her to develop copper deficiency symptoms. Copper is not common in the body; our body contains about 1.4-2.1 mg Cu/kg of body weight. It is concentrated in the liver, muscle and bone and it’s involved in mitochondrial functions as well as anti-inflammatory and antioxidant functions via superoxide dismutase. Copper is needed for blood vessel formation, heart health, and collagen and connective tissue growth and is also required for neurotransmitter synthesis.
Deficiency symptoms are mostly hematological (microcystic anemia) and neurological. Microcytic anemia is the result of low copper levels causing a deficiency of ceruloplasmin, which is needed for iron absorption in the digestive tract. Few iron supplements contain copper, but this is a great mechanism to understand if you are constantly fighting someone’s iron deficiency anemia.
Low copper is also now associated with, and in some cases becoming a treatment for, atherosclerosis, ALS, and osteoporosis. Too much of a good thing is problematic however, with copper excess as a known cause of Wilson's disease where it can cause cirrhosis, increased skin pigmentation, eye changes, and diabetes, but new research is also investigating high copper as a problem in epileptics, Alzheimer’s disease, and cancer (ovarian, breast, gastric, bladder, and leukemia). Research into therapies to chelate copper and also to replace copper for disease management is ongoing.
- Estimated average requirements 0.7 mg/day; RDA 0.9 mg/day
- RDA pregnancy 1 mg/day
- Lactation 1.3 mg/day
- Upper limit (UL) of safety is 10 mg/day; Europe’s UL is 5 mg/day
Testing magnesium level is tricky as normal serum values are found to be inadequate. That’s why we test it in a whole blood spot collection as it provides an RBC (red blood cell) magnesium level.
Amazing magnesium fact: it's the third most common element in sea water behind sodium and chloride. It's the 4th most common element on earth and you'll be glad to know that if you go Mars, it's extremely common on that planet. Phew, no worries there, you just have to dig it up.
Magnesium is one of the most common elements in the human body, concentrating in the bones, brain and heart, but essential in all cells and used in over 600 enzymatic reactions. Anything from synthesizing proteins, to activating vitamin D, to metabolizing dopamine and glutamate requires magnesium. It’s been found useful for numerous clinical conditions such as hypertension, migraines, insomnia and leg cramps. And we are commonly deficient – about 2-15% of the population. It causes cramping in all muscles, the heart being the most important, tremors, hypertension, and neuromuscular and metabolic dysfunction.
Through our diet, we get magnesium from spices, nuts, grains, cocoa (my favorite source) and vegetables (particularly dark green leafy veggies). But high or low protein diets can inhibit absorption, and people on proton pump inhibitors are commonly deficient. Levels are also commonly lower in people with diuretic usage or kidney problems.
Medications often deplete magnesium, but some medications actions may also be inhibited by magnesium. The body contains approximately 22-26 g of magnesium (vs. copper’s average of 100 mg) – mostly in the skeleton. But testing it is tricky as normal serum values are found to be inadequate. That’s why we test it in a whole blood spot collection as it provides an RBC (red blood cell) magnesium level. In fact, only when you are severely depleted do serum levels drop.
- RDA (diet + supplementation): 400-420 mg/day for men; 310-320 mg/day for women
- Adult upper limit of tolerability is 350 mg/day (level at which no diarrhea or GI complaints will occur)
- Toxicity has occurred at 5,000 mg/day
Ok, so selenium isn't a metal, but it is a mineral and we really need it for the voyage. Astronauts living at the International Space Station have found that cells secrete large amounts of inflammatory cytokines and express more than 1000 different genes from being at microgravity, not to mention the exposure to space radiation; all of this creates significant oxidative stress and inflammation. The longer the voyage, the more reactive oxygen species (ROS) damage occurs which actually gets worse upon returning to earth’s gravity.
Selenium is an amazing antioxidant through the actions of selenocysteine and selenomethionine. Selenocysteine is critical in glutathione peroxidase, but is known to contribute to 25 selenoproteins at this time. Selenium is also critical in 3 iodothyronine deiodinases making selenium one of our important thyroid nutrients. In fact, selenocysteine or selenomethionine is found in high concentrations in areas that experience high ROS – sperm, thyroid, liver, kidney and muscles. Selenium is found in Brazil nuts, grains, seafood, organ meats, poultry and dairy products. You can also find it in garlic, onions, and broccoli if the soil is rich in selenium, which is thankfully plentiful in Martian dirt. Low levels of selenium are likely a contributor to rapid aging, as well as immune dysfunction, thyroid dysfunction, and cancer. High blood levels of selenium may decrease blood sugar control.
- RDA: 55 mcg adults; 60 mcg pregnancy; 70 mcg lactation
- Tolerable upper limit 400 mcg/day
- Toxic level 800 mcg/day
Zinc on Mars apparently warranted a news headline in 2011. So, you might be able to find it if you look hard enough, but this is one that you might want to bring with you. Zinc deficiency is estimated to affect up to 2 billion people worldwide. People with the genetic disorder acrodermatitis enteropathica, alcoholics, or those who have severe burns, prolonged diarrhea, or are on total parenteral nutrition or certain medications can become severely low. Milder deficiencies are common with children, people with malabsorption or malnutrition, strict vegetarians or vegans, or older individuals. I personally saw a patient with profound zinc deficiency who was many years post gastric bypass.
Zinc is needed for over 300 enzyme conversions just like magnesium. We also know that zinc plays a critical role in regulating genes and cell signaling (remember zinc fingers in hormone receptors? Yup, they contain actual zinc). So zinc impacts almost every system in the body including the immune system.
If you are deficient, immune dysfunction and growth restriction, failure to thrive, and neurological impacts on children may occur. Clinically, there are several exciting paths that zinc research is investigating including using it as treatment for: athletic training, copper chelation protocols, immune regulation, macular degeneration, diabetes, diarrhea, atherosclerosis, and child development in developing countries. So, when packing your food for Mars, consider packing shellfish, red meat, eggs, grains, nuts and legumes. Non-meat sources are less bioavailable due to their phytate contents, so pack extra. Note, intranasal zinc treatments have been known to cause an individual to permanently lose their sense of smell, so caution here.
- RDA: 11 mg/day men; 8 mg/day women
- Toxicity levels: Single dose of 225 mg or more will induce vomiting. Symptoms of nausea, diarrhea, sweating, weakness and rapid breathing can also occur. Major toxicity is caused by copper deficiency
- Upper tolerable limit: 40 mg/day
There is no doubt that if we ever do undertake a trip to Mars, careful nutritional guidance is going to be needed to prevent severe deficiencies. If you bring nothing else along, pack some nuts. The trip is going to take a while.