How can we be certain that an anti aging diet works? The answer to this question will involve quite a bit of discussion and thought; we will attempt to keep it simple and concise. In brief, the truth that an anti aging diet works involves the following 4 considerations:
1. Determining what is an "anti aging" diet is.
2. Understanding the difference between anecdotal and scientific data and how this relates to the question.
3. Considering the additional factors.
4. Understanding what the data really tell us.
What is an "anti aging diet?"
For purposes of our discussion, we will define an anti aging diet as one that, over time, ameliorates the negative effects of aging. Thus we would expect an anti aging diet to affect, at least in a limited sense, the underlying aging processes and outcome.
What is the difference between anecdotal and scientific data and how does this relate to the question?
We live in a society that generally confuses anecdotal and scientific data. "It works for me," "When I eat this I feel better," and "I ate that and had a bad reaction" are all anecdotal statements. Anecdotal data are information that is gathered on a catch-as-catch-can basis. They are highly subjective data based on our day-to-day observations and experience. The problem is that a) anecdotal data may not be true and b) anecdotal data from one person may not be relevant or true for another person.
Anecdotal data may not be true. Anyone can say, "It works for me," when it doesn't, or "When I eat this I feel better," when they don't, or "I ate that and had a bad reaction," when they didn't. If a person really desires to make a certain point, he or she may well fabricate the anecdote to support their preconception. Whenever someone makes a claim, we should ask, "How do we know that this is a true statement?" In the case of anti aging diets, just because someone supports the claim or declares that the diet has helped them, these claims, in and of themselves, do not establish veracity.
Anecdotal data from one person may not be relevant or true for another person. Even when anecdotal data are true, the generalizations that they support, or attempt to support, may not be relevant. "It works for me, so it will work for you" or "I ate that and had a bad reaction so you shouldn't eat it" are each statements that draw generalizations from the anecdotes. Even if the specific statements are true, the generalization may or may not be; stated differently, the anecdote in and of itself does not prove the generalization (that it will truly impact everyone because it impacted some specific individual).
In contrast to anecdotal data, scientific data are gathered in a planned and appropriate fashion. Planned, in that we have established the experimental plan before hand; scientific data are not gathered in a catch-as-catch-can fashion. Appropriate, in that the data collected are sufficient to substantiate the claim; scientific data, unlike anecdotal data, can be generalized if the foundation of the scientific study is appropriate. Stated another way, scientific data are rigorously planned and statistically appropriate to answer the question at hand. Here are some considerations on using the scientific method to determine if anti aging diets work:
1. People generally (and hopefully, I might add) live so long that it is difficult to plan and execute a prospective study to determine if anti aging diets work. Thus the bulk of data on anti aging diets have been obtained with mice or rats, based on the measurement of factors that are believed to be related to a longer life (eg., better blood pressure, lower cholesterol), or done retrospectively using population statistics to determine if a given factor is important for longevity.
2. The experiment to establish the veracity of an anti aging diet needs to be well controlled, meaning that one set (or cohort) of individuals would be on the anti aging diet while the other cohort would not be on the diet. Again, it is easier to do this using a model animal, such as mice.
3. In the experiment, additional factors that might have an impact on longevity also need to be controlled. The study population needs to be selected or controlled in some fashion such that the data are not confounded by other factors. Again, mice are far easier to control than humans. More on this below.
The Confounding Factors:
Aging is a complex affair and an anti aging diet is only a part of the story in longevity. Other factors, as mentioned below, influence aging and well being. In total, these factors, along with a healthy anti aging diet, should result in a longer life. Here is a condensed list of additional factors:
1. Genetics. Some families are comprised of progeny that live long; others of those that tend to die at a younger age. Other families tend to be composed of overweight individuals, still others of those who are prone to disease, such as heart disease or diabetes. Diet and exercise can influence "bad genes" but these things may not totally eliminate genetic issues.
2. Risk Taking. Some people seem to be driven to take risks and do things that may result in an early death. It is important to have a life that adequately challenges you, but there is a point at which taking risks may not be healthy.
3. Supplement use. There are many vitamins, supplements, and micro nutrients that may well impact how a person ages and even how long that person lives. Many of these may be a part of any well balanced diet but it might be prudent to supplement your diet with supplements.
4. Exercise. Numerous studies have shown that people who exercise tend to live longer and more healthy lives.
5. Relationships. Other studies have shown that people who are involved in daily, meaningful relationships tend to live longer and more healthy lives.
6. Spiritual Life. The items above can be controlled in a study that utilizes mice. It is not possible to do this, however, with regard to spiritual life. Nevertheless, there are retrospective data that support the hypothesis that a person's spiritual life, in general, does impact his or her health and longevity.
What Do the Data Really Tell Us?
For the above reasons, there are few direct, solid, prospective experimental data showing that anti aging diets extend lifespan in humans. Virtually all of the prospective data that directly measures longevity comes from animal models, and animal model data may or may not apply to humans. There are prospective data in humans measuring factors that are believed to be related to longevity and there are much retrospective data from large human populations that seem to indicate that diet, along with the additional factors listed above, do influence longevity. But the statistics and population selection are complex and sometimes difficult to understand for these retrospective studies. Thus, it is easy to rely on anecdotes in our quest to determine if anti aging diets work. This is something that we must resist if we desire to understand what is known regarding anti aging diets and what is mere speculation. Unfortunately, speculation tends to be rampant and truth elusive.
