Cholesterol as a Sign of Malnutrition and Increased Mortality
As a dietitian and healthcare provider, most of us are taught that for cholesterol, high is bad and low is good. We are seldom concerned with cholesterol unless it exceeds 200 mg/dL. It is rarely discussed that cholesterol, or rather low cholesterol, can be an indicator of malnutrition and increased mortality in the older adult. Perhaps this is something new to you as well. Let’s dig into malnutrition and the role of cholesterol in both malnutrition and mortality risk.
What is Malnutrition?
Malnutrition is defined as: “Inadequate intake of protein and/or energy over prolonged periods of time resulting in loss of fat stores and/or muscle stores, including starvation related malnutrition, chronic disease or condition-related malnutrition and acute disease or injury-related malnutrition (1).” In other words, malnutrition is what happens when someone does not get the nutrition they need and overtime they start losing both muscle and fat stores.
Malnutrition in the older adult comes with many grave consequences- from loss of independence, increased risk of falls, increased hospitalization, and increased risk of mortality. It is estimated that 35-65% of hospitalized older adults in Europe and North American are malnourished (2). We are currently seeing unprecedented growth in the older adult population with the aging of the baby boomers. With this trend we will likely see even more older adults both at risk for and with malnutrition.
What Causes Malnutrition in Older Adults?
Malnutrition is often multifactorial and complex. It is something that occurs over time and very seldom pops up overnight. The cause of malnutrition varies from individual from individual, but there are often overarching themes in the cause of malnutrition in older adults.
The most common causes of malnutrition in the older adult are dietary restrictions, catabolic illness, blood loss, poor appetite, dysphagia, polypharmacy, malabsorption issues, psychosocial issues including loss of loved ones and loneliness, dementia, and even simply a nutrition-related knowledge deficit (3). Frequently it is not just one of these causes, but it is multiple causes that lead to malnutrition.
Take, for example, an older adult who lives alone and has no living family. They take many medications and have a poor appetite. Their new medical provider sees they have heart disease in their diagnosis list and recommends they start a low sodium diet. The older adult cuts out all salt because they want to be healthy, but then nothing tastes good- considering they have a poor appetite to start with and have no one to eat with… they may simply not eat. The result over time is unintended weight loss and subsequent malnutrition. It’s a story all too common in the older adult.
How is Malnutrition Diagnosed?
Dietitians play an important role in the identification and diagnosis of malnutrition. In 2012 the Academy of Nutrition and Dietetics (Academy) and the American Society for Parenteral and Enteral Nutrition (ASPEN) recommend that a standardized set of diagnostic characteristics be used to identify and document adult malnutrition in routine clinical practice (4). This is something that all dietitians should be incorporating into their practice.
In a consensus statement, it was recommended that identification of two or more of six specific characteristics were necessary for the diagnosis of adult malnutrition. These characteristics include: insufficient energy intake, weight loss, loss of muscle mass, loss of subcutaneous fat, localized or generalized fluid accumulation, and diminished functional status as measured by hand-grip strength (4).
You may notice that the last four characteristics are all physical findings. This is also why it is so important that dietitians learn and implement the nutrition focused physical exam into their everyday practice. You may also notice that no labs are used in the diagnosis of adult malnutrition.
In the past, albumin was used as an indicator of malnutrition. But we know that albumin is a poor indicator of malnutrition due to the long half-life and because other factors, not related to nutrition, can impact albumin. Age, declining liver function, inflammation, hydration, and medical issues can all have an impact on albumin (3). Sometimes medical providers will still use albumin as an indicator for malnutrition, but this should not be used.
While we don’t use labs in the identification and diagnosis of malnutrition per ASPEN/Academy, it is interesting to note that cholesterol may be an indicator of malnutrition and may be a predictor of mortality. Historic cholesterol levels must be considered when evaluating the risk for malnutrition along with utilizing the guidelines for the assessment of malnutrition per the consensus statement from ASPEN and the Academy. Let’s look more into the research on cholesterol, malnutrition, and mortality risk.
Cholesterol and Malnutrition
In 2017 a systematic review and meta-analysis investigated blood biomarkers associated with risk of malnutrition in older adults. Researchers looked at 111 studies representing 52,911 older adults in a variety of care settings from homes to hospitals. This study found that BMI, hemoglobin, and total cholesterol are all useful for the identification of malnutrition in older adults (5). Interesting, right?
One of the reasons we don’t use albumin in the identification of malnutrition is that so many different variables outside of nutrition can affect this lab value including acute disease. What’s interesting is that total cholesterol was not found to be sensitive acute disease status. Researchers even concluded that total cholesterol was useful in the identification of malnutrition even in the presence of chronic inflammation (5).
So, at what level did researchers find cholesterol could indicate a malnutrition risk? Researchers concluded that “hypocholesterolemia”, serum cholesterol levels less than 160 mg/dL, reflected a malnutrition risk. Researchers were quick to emphasize that biochemical markers are just one indicator of malnutrition. But the reality is that we could be underdiagnosing malnutrition in older adults if we are not considering this biochemical marker (5).
What this large study is telling us is that low total cholesterol can indeed be an indicator of malnutrition in older adults. In order for us to be sure we are identifying and treating malnutrition in all older adults, this biochemical marker may be one more tool in our toolbox for assessing the older adult.
Cholesterol and Mortality Risk
Cholesterol isn’t just an indicator of malnutrition, but it is also an indicator of increased mortality risk in the older adult. So often the focus on cholesterol is on high cholesterol, or hypercholesterolemia, and lowering cholesterol levels to decrease mortality risk. But let’s look at what the research has to say about hypocholesterolemia and mortality risk.
A 2005 prospective cohort study looked at 2,277 community dwelling Medicare recipients age 65 and older. Researchers wanted to investigate the relationship between cholesterol and the risk of all cause death in older adults without dementia (6).
What researchers found was that hypocholesterolemia was a strong predictor of mortality in the nondemented older adult. They suggest that hypocholesterolemia may be a surrogate of frailty or subclinical disease. They acknowledged that more research was needed to fully understand these associations (6).
What was interesting about this study was that researchers found that older adults with the lowest levels of cholesterol were twice as likely to die as those in the highest levels (6). It makes you wonder why we don’t put as much focus on low cholesterol as much as we do high cholesterol, especially when low cholesterol can be just as deadly or even more so in older adults.
In 2012 another study investigated the role of cholesterol and mortality risk in the older adult. This 12-year cohort study followed 800 older adults. This research also found higher mortality among older adults with low total cholesterol. Of note they found no positive associations between hyperlipidemia and all-cause mortality (7).
This study made a point to exclude underweight and premature mortality to really put the focus on cholesterol. They found a positive association between total cholesterol <170 mg/dl and mortality even after these two items were excluded (7). Researchers encouraged more research in this area so we can continue to get a better understanding on what is going on.
What do we do with this information?
While more research may be needed to understand why cholesterol is associated with malnutrition and mortality, this is something that we can use now in clinical practice. When conducting a thorough nutrition assessment with the older adult, consider the role of low cholesterol in your assessment.
We know that like so many other indicators of health, there is a u-shaped correlation between cholesterol and mortality (8). There are health risks at both end of the spectrum. Interpretation of cholesterol is more complex than simply saying “lower is better.”
To wrap things up, let’s summarize what we have learned. Cholesterol is a biochemical marker frequently utilized in healthcare systems and a measure that most dietitians use in their practice. When working with older adults, practitioners need to consider the role of low cholesterol on malnutrition and mortality risk. Along with a comprehensive nutrition assessment, cholesterol can be used as one more tool to help the practitioner identify risk and tailor interventions to best meet the needs of the older adult.
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2. Fávaro-Moreira NC, Krausch-Hofmann S, Matthys C, et al. Risk factors for malnutrition in older adults: a systematic review of the literature based on longitudinal data. Advances in nutrition. 2016 May 9;7(3):507-22.
3. Niedert K, Carlson, M. Nutrition Care of the Older Adult. Chicago, IL: Academy of Nutrition and Dietetics; 2016.
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7. Cabrera M, Andrade S, Dip R. Lipids and All-Cause Mortality among Older Adults: A 12-Year Follow-up Study. Scientific World Journal. 2012; 2012.
8. Tsabar N, Press Y, Rotman J, et al. The low indexes of metabolism intervention trial (LIMIT): design and baseline data of a randomized controlled clinical trial to evaluate how alerting primary care teams to low metabolic values, could affect the health of patients aged 75 or older. BMC health services research. 2018 Dec;18(1):4.