Why healthspan is the new focus of geroscience
“Life is short, and the older you get, the more you feel it. Indeed, the shorter it is.” This quote by actor Viggo Mortensen sums up how many people feel when they reach middle age and beyond. They start to realize how important it is to use the time they have wisely, and also that they best heed their body’s physical cues lest they want to hobble around all day after intense physical exertion.
At the same time, life is long. As noted in a documentary titled The Healthspan Imperative, the human race has enjoyed an unprecedented increase in lifespan over the last century. Through advances in medical science, many can expect to live life well into their 80s, 90s, and beyond.
But this increase in longevity has not come without consequences. A substantial part of life now occurs over the age of 65, when the risk for frailty and disease increases exponentially. Eighty-six percent of older adults have at least one chronic health condition, such as hypertension, coronary heart disease, diabetes, cancer, arthritis, hepatitis, weak or failing kidneys, asthma, and/or COPD (chronic obstructive pulmonary disease).[1] Moreover, 60% of older adults are battling two or even three of these conditions.
Aging and its diseases are inseparable, as these diseases are manifestations of aging.
To address this “Silver Tsunami” of disease and disability there is an increasing focus on healthspan, a term that refers to the period of life spent in good health and free from the chronic diseases and disabilities of aging.[2],[3] Healthspan research is based on the concept that chronic, age-related conditions, including heart disease, cancer, and dementia, all share the same trigger: aging itself.[4],[5],[6] As one researcher puts it, “Aging and its diseases are inseparable, as these diseases are manifestations of aging.”[7] Thus, if we can slow down the underlying processes that define aging, such as oxidative stress and inflammation, we should be able to delay the development of many diseases.[4]
While the definition and measurement of healthspan needs refinement, there is broad agreement that delaying the onset of disease, and expanding the period of life spent in good health, is of the utmost priority.[3] Some groups are searching for drugs that can inhibit key biological pathways, while others are investigating the influences of lifestyle and nutrition.
The New England Centenarian Study, the largest comprehensive study of centenarians in the world, found that individuals who reach the age of 100 and beyond manage to delay disability towards the very end of their lives.[8],[9],[10] By studying their genetics and habits, we may be able to glean the secrets behind their long and healthy lives. While genetics plays an important role in healthspan,[11],[12] the main attributes that healthy elderly people share is that they have very good lifestyle choices, as discussed below.
Lifestyle is a key determinant of aging
Many of us have the capacity to make it into our early 90s, without chronic disease, by adopting healthy habits.[9],[13],[14] One study found that people ages fifty and older who had never smoked and were not obese, and who consumed alcohol moderately, delayed the onset of disability for up to six years as compared to the population overall.[15] And another study showed that people aged 70 to 90 years who adhered to a Mediterranean diet, were physically active, refrained from smoking and consumed alcohol moderately, had a 50% reduction in mortality from all causes.[16]
Social connections and intellectual activities strongly influence healthspan. Even though they are more commonly associated with psychological effects, their physiological effects are also substantial.[17] Individuals living in so-called Blue Zones, areas around the world where centenarians are concentrated, have not only healthy lifestyles but also strong social networks.[9]
In a small town in Minnesota (Albert Lea; population 9000) where Blue Zone practices were implemented – including a central community walking path, which not only encourages daily activity but also is a place where one runs into friends and neighbors, and improving food selections at restaurants and grocery stores – there was a 3.2-year increase in life expectancy after only 18 months, and health care costs dropped by 40%.[9]
Physical activity is essential
“Developing ways to limit sedentary time and increase activity at any level could considerably improve health and reduce mortality,” say the authors of a 2019 study.[18]
Skeletal muscle mass and strength decline as we age, but the rate of decline is greater in those who are sedentary.[19] Muscle weakness is associated with a significantly increased risk of metabolic syndrome,[20] heart disease,[21] Alzheimer’s disease,[22] and all-cause mortality and disability.[23],[24] Regular exercise can help stave off a large number of age-related conditions.[25],[26],[27]
Together with physical activity, it’s important to consume enough dietary protein.[28] Aging muscles develop anabolic resistance, which means they do not respond as well to the presence of essential amino acids.[29],[30] Consuming high-quality proteins, such as fish, soy, and whey protein, helps support muscle protein synthesis as we age.[31],[32],[33]
Consuming high-quality proteins, such as fish, soy, and whey protein, helps support muscle protein synthesis as we age.
What do healthy centenarians eat?
Calorie restriction has been in the news as a possible strategy to increase lifespan and delay disability.[34],[35] Although maintaining a healthy body weight is desirable, extreme calorie restriction seems to impair the body’s ability to fight infections and to heal from injury.[34] Healthy centenarians maintain a low-normal body weight by eating moderately, for example by putting down their forks when they are 80% full, and by moving more.[9],[36]
Most healthy centenarians consume plant-based dietary patterns that include a variety of fruits, vegetables, legumes, nuts, and whole grains, and often include fish.[37],[38] Such diets provide high levels of dietary fiber, antioxidants, unsaturated fatty acids, polyphenols, and vitamins, all of which help reduce the risk for age-related diseases and disability.[39],[40],[41],[42]
A study of adults aged 49 years and older found that participants with the highest dietary fiber intakes had the greatest odds of aging healthfully, compared to those consuming low fiber diets.[43] “These findings suggest that increasing intake of fiber-rich foods could be a successful strategy in reaching old age disease-free and fully functional,” say the authors. Even in midlife, healthy dietary changes (increasing vegetables and fruits, improving quality of fats, decreasing sugar and salt) were found to be associated with a reduced risk of dementia.[42]
Dietary fiber exerts its benefits, in large part, by keeping the gut microbiota healthy. As we age, the numbers of beneficial bacteria and overall diversity decline, while harmful species proliferate.[44],[45],[46] This imbalance (dysbiosis) contributes to leaky gut, inflammation, and immune dysfunction,[47],[48] and increases the risk of various age-related diseases.[49],[50],[51] Several types of dietary fibers serve as prebiotics— substances that induce the growth or activity of microorganisms that enhance the wellbeing of their host.[52],[53] In addition to a high-fiber diet, supplemental prebiotics, probiotics, or synbiotics (prebiotic/probiotic combinations) are often used to support the microbiome.[54],[55],[56]
Dietary fiber exerts its benefits, in large part, by keeping the gut microbiota healthy.
The importance of micronutrients for healthy aging
Insufficient levels of micronutrients, including vitamins B12, C, D, E, iron, and zinc are relatively common in older adults.[57],[58],[59] Even on the Mediterranean diet, for example, 80 to 90% of adults do not meet recommended intakes for vitamin D.[60],[61] Nutrient absorption also can decline due to an age-related reduction in stomach acid.[62],[63],[64] Among other problems, low absorption contributes to vitamin B12 deficiency, anemia, and peripheral neuropathy.[65],[66]
Vitamin and mineral deficiencies in older adults are related to increased risks of disability and age-related diseases.
Vitamin and mineral deficiencies in older adults are related to increased risks of disability and age-related diseases.[67] Although many nutrients are important for healthy aging, some of the most notable include:
Vitamin D: Vitamin D is believed to be a primary anti-aging nutrient due to its numerous positive effects in laboratory, animal, and human studies.[68],[69],[70],[71] Vitamin D levels decline with age,[72] and low levels are associated with an increased risk for osteoporosis,[73],[74] respiratory infections,[75] metabolic syndrome,[76] heart disease,[77],[78] breast cancer,[79] and Alzheimer’s disease.[80] Since many adults (not just the elderly) are chronically deficient in vitamin D, supplementation may reduce these risks.[81],[82],[83]
Antioxidants: Cellular antioxidant levels decline with age.[84],[85] A Japanese study of more than 2000 older women found that diets with high amounts of antioxidants and high protein levels may be an effective strategy for frailty prevention.[86] Antioxidant nutrients such as vitamin E (tocopherols and the corresponding tocotrienols)[87] and coenzyme Q10 (CoQ10) seem to be particularly important for aging muscles and the heart.[88],[89] Growing evidence also supports a role for additional antioxidant nutrients, including lutein, zeaxanthin, and astaxanthin, in the support of eye health and vision.[90],[91],[92]
Omega-3 fatty acids: Omega-3 polyunsaturated fatty acids, which are associated with heart health,[93] help support the brain during aging.[94] Individuals who consume diets enriched with omega-3 fatty acids have a reduced risk of Parkinson’s and Alzheimer’s disease.[95] The authors of the latter study advised that “supplementation needs to be a part of a global lifestyle intervention and has to take place in the early stages of the disease, when a benefit may be detected.”
B vitamins: Low vitamin B12, B6, and folate levels increase blood homocysteine levels, thereby increasing the risk for stroke.[96] In fact, brain vitamin B12 levels decline nearly threefold with advancing age.[97] Low B12 and folate levels can also increase the risk for cognitive impairment.[98],[99] Intervention trials in older individuals with cognitive impairment have shown that B vitamin supplementation not only lowers homocysteine, but markedly slows the rate of brain atrophy and cognitive decline.[100],[101],[102],[103] Research also suggests that these B-vitamin-dependent effects can only be realized if there are adequate levels of omega-3 fatty acids.[104]
Summary
Life is short, but it also can be very long! The lessons learned from centenarians show that lifestyle, including diet and exercise, is a major determinant of healthspan. Targeted nutritional interventions can not only prevent overt deficiencies, but may also help ward off physical and physiological decline as we age. Nutrients that have been directly linked with healthy aging include high-quality protein, fiber, vitamin D, antioxidants, omega-3 fatty acids, and B vitamins.
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