How epigenetic alterations affect aging
Of all the factors that affect how we age, epigenetic alterations might be the most complex. Scientists are only just beginning to explore the cause and effect of aging on DNA alterations. Do we age because our cells change, or do our cells change because we age? Here’s what we know about what epigenetic alterations are, and how they relate to our bodies getting older. Most importantly, we’ll look at what we can do to delay epigenetic alterations and lead longer, healthier lives.
What are epigenetic alterations?
Almost all our cells contain DNA. It’s the blueprint for making us. Our DNA is bundled into groups of related code called genes, that determine how each part of our bodies develops and forms. For example, we have a gene for hair color, eye color, our height, and so on. Our genes are “read” by proteins, which build molecules according to the instructions in our DNA. The information our genes contain, and how it applies to new cells, is called “gene expression,” and the process of reading them is “transcribing.”
One of the ways that DNA is sorted into genes is through epigenetic markers. These are like punctuation in the DNA code, and tell cells how and when to read genes. There are two kinds of epigenetic markers, chemical and protein. Some are hereditary, while others accumulate over our lives as a result of diet and lifestyle.
Sometimes accumulated markers can become hereditary. A study on “Maternal high fat-diets and insulin-sensitivity in second-generation mice” found that epigenetic alterations that mice accumulated from their diets were passed on to their children and grandchildren. This resulted in decreased insulin sensitivity in the following two generations. When it comes to how our genes are processed, we are what our grandmothers ate.
As we age, so do our epigenetic markers. When this happens it is known as epigenetic alteration. Sometimes the cells formed by epigenetic alterations are the wrong cells entirely, and sometimes they’re the right cell but badly mutated. Either way, this isn’t good for us. Epigenetic alterations are factors in all kinds of age-related degenerative diseases and cancers.
Epigenetic changes aren’t the same as DNA mutations, which is another factor in aging. Epigenetics relate only to changes in how our DNA is read, that don’t affect the actual DNA sequence. The good news is because our DNA remains unchanged, epigenetic alterations could be reversible. It’s something that many researchers are studying, looking for a way to undo these alterations to prevent cancer and degenerative diseases.
The role of epigenetics and aging
Aging is characterized by epigenetic change. That means that there is a strong relationship between the two processes. Getting older contributes to the development of epigenetic alterations. One way this likely happens is through metabolic processes.
Getting energy from food involves a lot of complex chemical reactions. These create waste byproducts that affect our bodies at a cellular level. Heightened metabolic activity causes inflammation, which in turn is associated with epigenetic alterations. Therefore one of the ways we can slow this natural aging process is by eating a calorie-restricted diet.
The three pillars of epigenetic regulation
So how else are epigenetic alterations caused? There are three primary factors that affect epigenetic regulation. These are DNA methylation, histone modification, and noncoding RNA species.
Methyl groups are an alkyl that comes from methane, and are used to turn gene expression on or off by attaching to DNA. Hypomethylation is the state of losing methylation, and this activates gene expression. Hypermethylation is the opposite, when methylation increases and gene expression turns off.
Getting older is a known factor in methylation of different parts of the body. Certain genes, such as those that suppress tumors, become hypermethylated as we get older, meaning our risk of cancer increases as we age. A 2012 study of “Distinct DNA methylomes of newborns and centenarians” found that levels of DNA methylation could be predicted by our age. This suggests that methylation is a fundamental and inevitable process that we all go through.
While methylation might be unavoidable, we could be able to slow down this process and live longer, healthier lives. Research shows that certain vitamins and minerals are required for methylation. Getting enough of them into your diet can help support your DNA and avoid premature epigenetic alterations. Most important, according to current research, are the B-vitamins folate (B9), B12, and B6, and a similar nutrient called choline.
We can get B-vitamins from supplements, and also through our diets. Eating more salmon, eggs, milk, leafy greens, legumes, and fortified cereals can help replenish these vitamins. This is especially important for B-vitamins because our bodies can only store B12. The others have to be regularly replenished.
The second factor that affects epigenetic alterations is histone modification. Histones are proteins that our bodies use to store our DNA. Think of them like a spool, with DNA wrapped all around them. If the spool breaks, the DNA becomes unraveled and tangled, leading to damage.
Histones commonly break down during aging. In fact, histone loss occurs in all kinds of organisms, from humans all the way down to yeast cells. Histones can be affected by the enzymes used to transcribe genes, and especially by methylation. DNA attaches to histones through electrostatic attraction. Methylation can produce a positive charge that breaks that attraction, leading to the DNA unraveling.
A study on the “Interrelationships between energy metabolism and epigenetic control of gene expression” found that different diets can affect histones and cause more modifications than aging alone. Although researchers are still looking for the exact cause and effect relationship between diet and histones, high-fat and low-protein diets can result in significant histone changes. As with methylation, a calorie-restricted diet may have a positive impact in delaying these alterations. This isn’t surprising, because low-calorie diets also affect methylation, which is one of the primary factors affecting histone modification.
Noncoding RNA species
If DNA is the instruction manual for building our bodies, RNA is the substance that reads the instructions. RNA converts DNA information into proteins, which then form the molecules to build our bodies.
“Junk DNA” is the common term for all the bits of DNA that we don’t use to build our cells, but its proper name is noncoding DNA. Surprisingly, that’s most of our DNA — up to 98% of all the genetic information we carry. Noncoding RNA (ncRNA) is similar to noncoding DNA, and it is the name for all the RNA that doesn’t get translated into proteins.
That doesn’t mean that noncoding RNA is completely inert. Studies show that ncRNA plays a role in regulating gene expression. Abnormal cnRNA expression patterns occur in some cancers, Alzheimer’s disease, and autism, as well as other conditions. When ncRNA is functioning properly, it may act as a tumor suppressor and help process signals between cells.
The science of ncRNA is relatively new, and few of the tens of thousands of identified ncRNA types have been fully explored. That means we aren’t sure how best to support healthy ncRNA function and avoid mutations. However the fact that the diseases linked to ncRNA are triggered by metabolic changes and external damage such as that caused by UV light, pollution, and tobacco smoke, indicate that these factors have a role in causing ncRNA mutations.
How to delay premature epigenetic alterations
We can’t avoid alterations to epigenetic markers completely. Too many are caused by the normal functions our bodies have to perform in order for us to live. However we can help prevent the premature onset of these alterations by regulating what we eat. Consuming a wide range of vitamins, minerals, and other nutrients as part of a calorie controlled diet can help keep our cells functioning and allow us to live longer, healthier lives.