Selenium may reduce risk of syndrome linked to heart disease and diabetes; Animal study affirms mineral’s ability to block mercury impacts
by Craig Weatherby
Selenium is a metallic mineral that forms a critical part of the body’s internal antioxidant network.
This is because selenium is an essential component of an antioxidant enzyme called glutathione peroxidase
As such selenium is needed to control the oxidizing free radicals generated by normal metabolism and by pollutants and starchy, sugary foods.
Free radicals promote inflammation, so selenium is also needed to control this silent driving force behind heart disease, dementia, cancer, and diabetes.
According the U.S. National Institutes of Health, rates of death from major cancers is lower among people with higher blood levels or intake of selenium (NIH 2008).
The U.S. NIH makes this salient point about selenium and heart disease: “… it is the oxidized form of low-density lipoproteins (LDL, often called ‘bad’ cholesterol) that promotes plaque build-up in coronary arteries. Selenium is one of a group of antioxidants that may help limit the oxidation of LDL cholesterol and thereby help to prevent coronary artery disease.” (NIH 2008)
Given its role as an antioxidant, anti-inflammatory agent, it is not very surprising that a new study from Spain finds a link between higher selenium levels and reduced risk of metabolic syndrome.
Metabolic syndrome: The body’s own “cluster bomb”
According to the American Heart Association, more than 50 million Americans have metabolic syndrome (MetS).
This cluster of physiological characteristics is linked to increased risk of developing cardiovascular disease, stroke, and type 2 diabetes.
MetS is defined as having three or more of a half-dozen metabolic risk factors:
- Abdominal obesity (excessive fat tissue in and around the abdomen).
- High blood triglycerides, low HDL cholesterol and high LDL cholesterol: a state that fosters plaque buildups in artery walls.
- Elevated blood pressure.
- Insulin resistance or glucose intolerance (the body can’t properly use insulin or blood sugar).
- Pro-thrombotic state that promotes dangerous clots (e.g., high fibrinogen or plasminogen activator inhibitor–1 in the blood).
- Selenium in Vital Choice seafood
The adult RDA ranges from 55 to 70 micrograms (mcg), and the Upper Intake Level is 400 mcg per day (NIH 2008).
Micrograms selenium per 100 gm (3 oz)
- Canned Albacore Tuna
- Mackerel (Atlantic)
- King (Chinook) Salmon
- King Crab
- Silver (Coho) Salmon
- Sockeye (Red ) Salmon
Source: USDA Agricultural Research Service Nutrient Data Laboratory
- Pro-inflammatory state (e.g., elevated C-reactive protein in the blood).
The syndrome is very real and is largely responsible for the epidemic of cardiovascular disease and diabetes that’s exploding throughout the developed and developing worlds.
We’ve reported research that points to dietary patterns and food factors that appear to promote or deter MetS; to learn more, simply search our newsletter archive for “metabolic”.
And encouraging new research from a Spanish scientific team suggests that selenium may help prevent MetS.
Selenium may ease onset of metabolic syndrome
Researchers from Spain’s University of Navarra found that people’s selenium levels appear to regulate their body levels of a marker for increased risk of metabolic syndrome, called serum complement factor 3 (C3).
For their study, the Spanish team recruited 100 healthy young adults (average age of 21).
They recorded the subjects’ lifestyle patterns and blood pressure, and took finger nail samples to measure selenium levels (Puchau B et al. 2008).
The researchers found that higher C3 levels were linked to several key components of MetS, including body mass index (BMI), waist circumference, blood glucose levels, and blood triglyceride levels.
Their key finding was that higher selenium levels were associated with lower C3 levels.
As they wrote, “These findings suggest a possible role for selenium intake in the modulation of C3, [which] may be an early marker of metabolic syndrome ...”
Seafood is uniquely rich in selenium
Most people accumulate sufficient selenium from the small amounts in grains and most other plant foods.
Brazil nuts are the richest food source of selenium, but their selenium content varies widey, and eating too many can produce unsafe body levels.
Otherwise, animal foods are the richest sources, but seafood averages twice as much selenium as beef or chicken (NIH 2008).
And, unlike standard meats from factory farmed livestock, wild seafood is rich in omega-3s and low in omega-6s.
Together with an abundance of selenium, their desirable fat profiles make wild fish and shellfish much better choices than meats for discouraging development of MetS.
Better yet, selenium appears to blunt the health impact of mercury very substantially. This evidence-based hypothesis was affirmed by an animal study published last year in which selenium protected young rats from the ill effects of high mercury intake (Ralston NV et al. 2007).
Selenium's mercury-binding property may explain why the best-designed study of the effects of eating copious amounts of ocean fish found no adverse health effects in children. (See “Mercury-Fighting Mineral in Fish Overlooked in Heated Debate” and “Fight Over Mercury Risks Muddied by Bad Science”.)
The U.S. recommended daily allowance for selenium ranges from 55 to 70 micrograms (mcg) for people aged 14 or older, while the recommended Upper Intake Level is 400 mcg per day (NIH 2008).
So when you think of foods that deliver potent antioxidants, don’t forget fish. Without ample selenium, your body’s antioxidant defenses will be hobbled, leaving you open to silent, gradual harm.
- Choi AL, Budtz-Jørgensen E, Jørgensen PJ, Steuerwald U, Debes F, Weihe P, Grandjean P. Selenium as a potential protective factor against mercury developmental neurotoxicity. Environ Res. 2008 May;107(1):45-52. Epub 2007 Sep 12.
- Office of Dietary Supplements, National Institutes of Health (NIH). Dietary Supplement Fact Sheet: Selenium. Accessed on line Noember 23, 2008 at http://ods.od.nih.gov/factsheets/selenium.asp
- Puchau B, Zulet MA, González de Echávarri A, Navarro-Blasco I, Martínez JA. Selenium intake reduces serum C3, an early marker of metabolic syndrome manifestations, in healthy young adults. Eur J Clin Nutr. 2008 Nov 5. [Epub ahead of print]
- Ralston NV, Blackwell JL 3rd, Raymond LJ. Importance of molar ratios in selenium-dependent protection against methylmercury toxicity. Biol Trace Elem Res. 2007 Dec;119(3):255-68.