A number of products, including diets, drugs and supplements, are promoted to have anti-aging properties. Unfortunately, the hype is often undeserved. Here, I review the most famous products aimed at delaying the aging process and the misconceptions in which most--but not all--are based. Future anti-aging therapies and some advice on healthy lifestyles is also included.

Caloric Restriction Hormonal Therapies Antioxidants Telomere-Based Therapies Stem Cells ALT-711 Future Therapies The Not-So-Secret Guide to a Long, Healthy Life Conclusions

Keywords: ageing, anti-oxidants, anti-aging pill, anti-aging products, antiaging, biomedical gerontology, elderly, eternal youth, growing young, healthy aging, old age, rejuvenation, science of longevity

I will be clear from the start: presently, there is no proven way to delay, even if slightly, the human aging process (Olshansky et al., 2002; Hayflick, 2004). Although companies, and often journalists and admittedly scientists too, like to tout whatever-anti-aging-product-is-currently-in-the-news as the "fountain of youth" or the "holy grail", the truth is we do not know of any way to even slightly delay the aging process, much less stop or reverse it (which is what the "fountain of youth" and the "holy grail" are all about). Unfortunately, understanding why a given anti-aging intervention is fantasy rather than science often requires time to gather the scientific data, which not everyone is willing or capable to do (Warner et al., 2005). If you are visiting this website to learn more about anti-aging science and longevity, rather than find out about the latest anti-aging trends in Hollywood, then the discussion below is for you.

It is important to note that it is possible to delay some of the many effects of aging. For example, if you avoid unprotected exposure to the sun, you can delay skin aging. Similarly, a balanced diet can lower the incidence of heart disease. Given the complexity of aging, however, delaying the onset of a single age-related disease cannot scientifically be considered as equivalent to delaying the aging process as a whole (Hayflick, 2004). Just because a given product or lifestyle delays the onset of a particular age-related change or pathology does not mean it delays aging, in the same way that antibiotics used to treat opportunistic infections in patients with AIDS, even if they preserve health, are not targeting the ultimate cause of AIDS which is HIV. As such, my aim in this essay is to discuss interventions in the context of whether they can delay the aging process rather than one of its many consequences.

There are also ways of living longer. Following all that motherly advice like regular exercise and adequate nutrition can make you live longer (Holloszy, 2000), as discussed further below, and any therapy that ameliorates mortality from a specific disease will increase longevity. Still, living longer does not necessarily mean that the fundamental process of aging has been slowed down. Living a healthy life will lower your mortality across the entire lifespan, even if there is no impact on aging and age-related changes. For example, longevity increased roughly 50% in the past century and yet there is no evidence people age slower; we live longer now mostly because deaths caused by infectious diseases have gone down (Hayflick, 1994, pp. 84-88). This important distinction holds true for animal studies. Royal jelly and fish oil can significantly increase the average lifespan of mice (Jolly et al., 2001; Inoue et al., 2003), and yet that does not mean that aging has been delayed by these treatments; all it means is that these nutrients are healthy. Therefore, a great deal of care is necessary when interpreting life-extension studies and there is a lot of controversy in what represents delayed aging.

So how can we determine whether a given intervention delays aging? Based on my definition of aging, a given intervention to be accepted as anti-aging must demonstrate that the onset or pace of multiple age-related changes, including pathologies, is delayed. In addition, while accurately quantifying the rate of aging is impossible, one method to estimate the rate of aging is to calculate the rate at which mortality increases with age and so determining whether a given intervention delays this rate can also help determine if the aging process was delayed (de Magalhaes et al., 2005). Any intervention that fails to meet these criteria cannot be considered as truly anti-aging, even if it extends average lifespan or delays a given age-related change. This debate concerning what anti-aging means is the major source of confusion concerning anti-aging medicine and is often used by companies and even scientists to mislead the public. Certainly, some products pitched as anti-aging may be healthy and/or may soften the effects of aging. For example, a given anti-wrinkle cream may ameliorate one particular effect of aging (wrinkles), but it will not impact on any other aging sign. Importantly, an anti-wrinkle cream will not increase longevity much less delay the mortality acceleration with age and hence its effects on aging will be so superficial that scientifically I do not think it can be considered as anti-aging.

To complicate matters even further, because studying aging in humans is extremely expensive and time-consuming, it is virtually impossible to test whether a given intervention or product delays aging in humans and thus testing whether a product impacts on aging is usually done in animal models. Because animals may or may not be representative of human biology, interpreting the life-extending effects of products in animals must be done with caution. Even studies in animals might be artifacts of particular experimental conditions. For example, one of the largest increases in lifespan (44%) by a product was obtained by feeding worms a synthetic antioxidant called EUK-8 (Melov et al., 2000). Other scientists, however, failed to reproduce these results (Keaney and Gems, 2003), even though EUK-8 was shown to increase antioxidant levels (Keaney et al., 2004), which suggests that possibly very peculiar conditions are necessary for this particular product to increase lifespan.

As detailed elsewhere, senescence.info is not a medical website. It is a website about aging, namely about the whole aging process with a special emphasis on human aging, and thus the following products are interpreted in view of their potential impact on the human aging process as a whole. Hopefully, I can demystify some of hype surrounding these products and, based on scientific evidence, help clarify what they can and cannot do. In the same way I find it crucial to highlight progress and potential in aging research and the possibility (no matter how distant and difficult) of curing aging, it is equally important to fight false publicity, particularly in a field with such a fraudulent past like aging research. Given the numerous products in the recent past thought to be useful and later proven to have negative side-effects (e.g., fen-phen and ephedra), and the lack of clinical studies for most anti-aging products, discussing the scientific evidence is vital.

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Anti-Aging Medicine: Current Therapies from the Science of ...