Two people of the same chronological age can have completely different life expectancies and quality of life. The difference lies in biological age. And unlike the number in your passport, biological age is something you can actually influence.
What is biological age?
Aging is a complex process driven by a range of factors. Two people of identical chronological age, meaning age based on date of birth, can have very different life expectancies and quality of life based on their biological age. Our genetic material (our DNA), our cells, and our tissues are exposed to constant wear from internal and external stressors. Over time this damages our DNA and reduces the number, or causes the death, of important cellular structures such as the mitochondria, where our energy is produced.
Your biological age is therefore your estimated age based on how old and damaged your tissues, organs, and DNA are.
Why does it matter to lower your biological age?
Aging is the most important risk factor for all chronic diseases, including diabetes, cardiovascular disease, cancer, and dementia. By slowing the pace of your biological aging, you have the opportunity to reduce your risk of these conditions and increase the number of healthy years in your life.
How is biological age measured?
There is no standardized, scientifically validated, and broadly accepted method or biomarker today that determines an individual's biological age. There are, however, a number of approaches that can be used to estimate it.
One is to estimate biological age visually, based on posture, muscle mass, movement patterns, and signs of aging such as gray hair and wrinkled skin. Another is to assess cognitive ability. A third is to evaluate an individual's vulnerability or morbidity through self-reported scoring of a range of physical symptoms.
Telomere length
Work has long been under way to develop biomarkers that can be measured in blood or saliva and provide information about an individual's biological age. One method available today is to measure telomere length. The DNA strand in our cells is organized into a set of chromosomes, and at the end of each chromosome sit telomeres, which protect the DNA strand during cell division. The shorter our telomeres, the faster we age, because cells eventually stop dividing once telomere length becomes short enough.
Epigenetic clocks
Additional methods for estimating biological age are based on what are known as age calculators. The most thoroughly studied has been developed by Dr Horvath and his team, based on the epigenetic clock theory of aging.
Epigenetics studies how various factors influence our genes and their expression in our cells. One of the most important mechanisms for regulating which genes are switched on or off in a cell is DNA methylation. This means that a methyl group, consisting of one carbon atom surrounded by three hydrogen atoms, binds to the DNA strand and thereby regulates gene activity. When several methyl groups accumulate on the DNA strand, the gene's activity decreases. When methyl groups are removed, the gene is switched on. Put simply, you want the good genes (for example those that counteract cancer growth) switched on and the bad genes (for example those that drive inflammation) switched off.
Horvath's DNAmAge epigenetic clock estimates biological age by measuring the age of the DNA methylation pattern at hundreds of sites along the DNA strand. Some parts of our DNA become more methylated as we get older, while others become less methylated.
A faster biological clock. Higher risk.
Marioni et al., Genome Biology 2015. Four cohorts, n=4,658, adjusted hazard ratio per 5 years of DNAm age acceleration vs chronological age.
How can you influence your biological age?
It may sound like a tired refrain, but most likely through your lifestyle choices. Epigenetic processes, which control which genes are switched on and off in our cells, are mainly influenced by external factors. The majority of these are related to lifestyle.
Some epigenetic processes can change quickly, but it is repeated lifestyle choices over time that matter most.
What is interesting is that these epigenetic changes through DNA methylation can happen relatively quickly. Methylation is constantly under way inside your cells, and at every moment decisions are being made about whether methyl groups should be added or removed from the DNA strand. So if you choose to sleep properly one night, eat unsalted nuts instead of chips as a snack, take a walk, or take time to relax with yoga or deep breathing, you contribute to the repeated lifestyle choices that, over time, likely matter most.
The opposite, of course, also applies. Poor sleep, excessive alcohol intake, and a visit to a fast-food restaurant can have a negative effect on DNA methylation.
Even though changes can happen quickly, it is the lifestyle choices you make repeatedly and over time that have the greatest impact on your future health and biological age. During cell division, epigenetic changes can persist and continue to drive disease processes in the cells. The remarkable thing is that, by changing your lifestyle, you can likely slow down and possibly reverse these processes through sustained healthy diet and lifestyle choices.
So far only a small number of studies have been published examining the influence of lifestyle factors on biological age. One recent study shows just how adaptable we are, and that in a short time (8 weeks) we can affect our health.
Treatment protocol, 8 weeks
The protocol used for the intervention group in the Fitzgerald study.
- 3 servings of liver per week
- 5–10 organic, free-range eggs per week
- 120–170 grams of animal protein per day from grass-fed, organically raised sources
- 500 ml dark leafy greens per day (spinach, kale, chard; not iceberg or romaine lettuce)
- 500 ml cruciferous vegetables per day (broccoli, cauliflower, kale, brussels sprouts, arugula, watercress, kohlrabi)
- 500 ml vegetables of varying color per day, to taste and in season (not potatoes or corn)
- 1–2 beets per day
- 4 tablespoons of pumpkin seeds per day
- 4 tablespoons of sunflower seeds per day
- 2 servings of berries or low-glycemic fruit per day (apple, pear, orange)
- At least one of the following per day: ½ tsp rosemary, ½ tsp turmeric, 2 cloves of garlic, or 2 cups of green tea
- Choose organic ingredients where possible
- Drink plenty of water
- Avoid eating between 7 pm in the evening and 7 am in the morning
- Include healthy oils (olive oil, flaxseed oil or pumpkin seed oil, coconut oil)
- Avoid all products with added sugar, candy, dairy, grains, and legumes
- Avoid all foods in plastic packaging
- Take 2 capsules of probiotics containing Lactobacillus plantarum per day
- At least 30 minutes of exercise at 60–80% of maximum heart rate, 5 days per week
- Sleep an average of at least 7 hours per night
- Deep breathing exercise, 5 minutes, twice daily
- Fitzgerald K, Hodges R, Hanes D, et al. Potential reversal of epigenetic age using a diet and lifestyle intervention: a pilot randomized clinical trial. Aging. 2021;13(7):9419–9432. PubMed
- Marioni RE, Shah S, McRae AF, et al. DNA methylation age of blood predicts all-cause mortality in later life. Genome Biology. 2015;16:25. PubMed
- Horvath S. DNA methylation age of human tissues and cell types. Genome Biology. 2013;14:R115. PubMed