When was the last time you paid attention to your nails aside from keeping them trimmed? While looking at your nails from time to time is normal, they actually provide a window to your current health. In a HuffPost article, aging and genetics expert David Sinclair, Ph.D., explains what your nail growth can tell you about your aging process, and the basis for his hypothesis, which was published way back in 1979.1
Nail Growth Is a Hidden Marker of Aging
The 1979 study referenced by Sinclair, published in the Journal of Investigative Dermatology,2 examined how the rate of nail growth declines over a person’s lifetime and what this means for aging.
• The link between aging and nails — Researchers at the Orentreich Foundation for the Advancement of Science followed the linear nail growth of 192 women and 79 men, ages 10 to 100, to determine how aging impacts this biological process. The findings revealed a consistent and predictable decrease in nail growth speed over a lifetime, with a clear connection to overall physiological aging and metabolic slowdown.
• Nails grow faster when you’re younger — The study found that human nail growth reaches its peak in the late 20s before gradually slowing down at a rate of about 0.5% per year. By the time a person reaches 100, their nail growth rate has declined by roughly 50%.
• Nail growth of men and women are different — Men’s nails initially grow faster than women’s, but once they reach 80 years old, women’s nails surpass men’s in speed. The research also showed that external factors like temperature, illness and nutrition influence nail growth, providing further insight into its role as an indicator of health and aging.3
One striking aspect of the study was the discovery of long-term nail growth cycles. The researchers observed alternating seven-year periods where nail growth either slowed gradually or declined sharply, showing that aging is not a simple linear process but follows a rhythm influenced by deeper biological mechanisms. This means that if your nails suddenly grow much slower than usual, you’re likely in a phase of accelerated biological aging.4
• Environmental and lifestyle factors play a role — The study found that nail growth rate responds to changes in temperature. When skin temperature was kept at 32 degrees Celsius (89.6 degrees Fahrenheit), nails grew at a rate of 2.0 millimeters (mm) per week.
When skin temperature dropped to 16 degrees C (60.8 degrees F), growth plummeted to just 0.08 mm per week. This suggests that colder temperatures slow circulation and metabolism, directly impacting nail growth. If your hands and feet are always cold, it not just discomfort — it’s a sign your circulation isn’t supporting optimal tissue regeneration.5
• Chronic conditions play a role — Conditions that impair circulation, such as diabetes and congestive heart failure, were associated with slower nail regeneration. Even minor infections temporarily reduced nail growth, highlighting how the body prioritizes vital functions over non-essential processes when under stress. If your nails have stopped growing or have become unusually brittle, it’s a likely sign of an underlying health issue that needs attention.6
• The role of hormones — The study noted that pregnancy accelerates the rate, likely due to increased blood flow and metabolic activity. Conversely, hypothyroidism — a condition where the thyroid gland underproduces hormones — was linked to significantly slower nail growth. If your nails are growing unusually slow, a thyroid imbalance might be a factor.7
A unique aspect of this study was Its inclusion of beagles as an aging model. Dogs, like humans, experience a decline in nail growth as they age, but their rate of decline is five times faster due to their shorter lifespan.
This cross-species comparison reinforces the hypothesis that nail growth rate is a fundamental marker of biological aging, not just a cosmetic concern. Whether human or canine, slower nail growth signals reduced cellular energy and metabolic function.8
Your Daily Activities and Habits Also Influence Nail Growth
In addition to what was discussed already, the researchers explored the impact of daily habits on nail growth.
• Activities that contribute to faster nail growth — Typing, playing piano or using hand tools were associated with slightly faster nail growth. The researchers hypothesize that movement and circulation-enhancing activities help sustain healthy nail regeneration.
• Activities that slow down nail growth — In contrast, smoking, which constricts blood vessels and reduces oxygen delivery, was linked to slower nail growth. If you want stronger, healthier nails, improving circulation through activity and eliminating harmful habits is key.9
Despite being published in 1979, the information provided here demonstrated that nails provide a measurable, non-invasive way to assess aging at a cellular level. While wrinkles and gray hair are the most visible signs of getting older, the rate at which your nails grow provide another indicator of your current metabolic health. By monitoring changes in your nail growth, you’ll have an idea into your body’s aging trajectory, allowing you to take action to support better health and longevity.10
Your Nails Reveal More Than Just Age
Moving forward to a more contemporary study published in the Indian Journal of Dermatology in 2011, researchers examined how aging affects the structure, color and overall health of nails in older adults. Researchers analyzed 100 individuals aged 60 and above, assessing common nail changes associated with aging and their potential connections to broader health issues.
• Nails weaken as a part of aging — The findings highlighted how nails progressively weaken, change color and develop ridges as part of the natural aging process. Additionally, the study identified nail disorders that become more prevalent in older adults, such as fungal infections and brittle nail syndrome.11
• The common denominator — The research found that 98 out of 100 participants exhibited at least one noticeable nail change. The most common included a dull, pale and lusterless appearance, affecting 73% of the group.12
• Other changes in nail health among the elderly — Examples include increased brittleness, thickening of the nail plate and the development of prominent ridges. Surprisingly, many participants were unaware of these changes until pointed out, suggesting that nail health often goes unnoticed despite its clear connection to aging and overall wellness.13
• A shift in nail composition — The study revealed that calcium levels in aging nails increased, while iron levels decreased. This imbalance affects nail hardness and flexibility, making them more prone to cracking and splitting.
Additionally, the nail bed — the tissue beneath the nail plate — undergoes changes with age, including blood vessel thickening and reduced elasticity. These structural shifts contribute to slower nail growth and a greater likelihood of nail abnormalities.14
Lunula visibility, which is the small, crescent-shaped area at the base of the nail, also decreased with age. While the lunulas are most seen on the thumbs, their visibility declined significantly in participants over the age of 70.15
This reduction is linked to diminished nail matrix function, meaning the cells responsible for nail growth become less active. When lunula visibility fades, it may indicate slowed cell turnover and reduced nail regeneration. If your lunulas have disappeared over time, it could be a subtle sign that your body’s metabolic processes are slowing down.16
Unseen Physical Changes That Occur in Nails
According to the researchers, surface texture changes were another major concern, which was brought on by different factors.
• A sign of an underlying deficiency — The study found that 85% of participants developed pronounced longitudinal ridges, which run from the base to the tip of the nail.17 According to a report from News-Medical.net, longitudinal ridges indicate an underlying nutrient deficiency.18
Additionally, 33% of participants experienced rough nails, 23% had transverse ridges (horizontal indentations), and 15% developed lamellar splits, where the nail layers peel apart. If you’ve noticed deep grooves or peeling, your nails are likely losing essential structural proteins as you age.19
• Temperature fluctuations affect nail health — Brittle nails were particularly widespread, affecting 40% of men and 26% of women in the study. Toenails were more commonly impacted than fingernails, likely due to increased pressure and friction from footwear. However, some participants exhibited brittleness in both hands and feet.
The researchers theorize that repeated cycles of hydration and dehydration, exposure to harsh soaps and chronic nutritional deficiencies contribute to this fragility. If your nails frequently split or break, it likely indicates that your diet lacks key nutrients needed for keratin production and nail strength.20
• Aging thickens nails — Onychauxis, a condition that thickens the nail plate, was also observed in 23% of participants. This issue was most common in the toenails, particularly the big toe, where pressure and reduced circulation contribute to excessive keratin buildup. Thickened nails are more difficult to trim, often leading to discomfort and an increased risk of fungal infections.21,22
How to Strengthen and Restore Aging Nails
If your nails have become brittle, slow-growing or thickened, it’s a sign that your body isn’t getting what it needs for proper cell regeneration. Addressing the root causes of nail aging means improving circulation, and ensuring your body has the right nutrients to build strong, healthy nails. Here are my recommendations:
1. Improve circulation to your hands and feet — Blood flow is what delivers oxygen and nutrients to your nails. If your nails are slow-growing or brittle, poor circulation is a potential culprit. To boost blood flow, keep your hands and feet warm, especially in colder weather. Cold temperatures slow circulation, which reduces nail growth.
In addition, move your fingers and toes frequently throughout the day. Typing, playing an instrument or even massaging your hands improves blood flow. Get regular movement — walking, stretching and even simple hand exercises help keep blood flowing to your nail beds.
Likewise, avoid smoking because it constricts blood vessels and reduces the oxygen supply to your extremities. For more information on the damaging effects of smoking, read “How Cigarette Smoke Weakens Lung Immunity and Fuels Chronic Inflammation.”
2. Support your nails with the right nutrients — Your nails are made of keratin, a protein that relies on key vitamins and minerals for strength and flexibility. To help in this regard, I recommend the following nutrients:
• Collagen — Adding collagen-rich bone broth to your diet provides amino acids that strengthen nails. As noted in Harvard Health Publishing, collagen is an important structural protein found in nails, as well as tendons, cartilage and your bones.23
• Biotin (vitamin B7) — This B-vitamin is necessary for keratin production. Pastured eggs and grass fed beef are great natural sources.
• Iron — According to the American Society of Hematology, iron-deficiency anemia causes nails to become brittle. If you’re experiencing this, increasing your iron intake through your diet will help. However, don’t go overboard because excess iron also threatens your health. For an in-depth guide on balancing your iron levels, read my article “High Iron Levels Threaten Bone Health and Increase Fracture Risk.”
• Magnesium — Essential for protein synthesis, magnesium ensures your body properly build nail tissue. Good sources of magnesium include potatoes, broccoli, bok choy, grass fed milk and white rice.
3. Prevent nail dehydration and structural damage — As nails age, they become drier and more prone to breaking. Keeping them hydrated and protecting them from unnecessary damage is key to maintaining their flexibility and strength.
Start by avoiding excessive water exposure when doing chores, such as washing the dishes. To protect your nails, wear gloves. Another strategy is using high-quality natural oil on your nails to lock in moisture.
Avoid synthetic lotions that contain alcohol. I also recommend minimizing the use of nail polish and harsh removers — acetone-based removers strip away natural oils, leaving nails brittle.24
4. Avoid hidden toxins in your diet — Certain foods contain toxins that accelerate nail aging by damaging keratin and reducing your body’s ability to build strong nails. That said, minimize your intake of vegetable oils like canola, soybean and sunflower oil. These are loaded with linoleic acid, which contributes to oxidative stress and weakens nail structure.
5. Address other underlying metabolic issues — Your nails reflect your metabolic health. If they are growing slow, ridged or excessively thick, it’s a sign that your body’s energy production is compromised. To start, check your thyroid function. Slow-growing nails are a common sign of hypothyroidism. On the other end of the spectrum, hyperthyroidism is characterized by brittle nails.25
Also, ensure you have an adequate protein intake, which is around 0.8 grams of protein per pound of lean body weight. One-third of this should be from collagen sources. Avoid fasting for extended periods. While short fasting windows can be beneficial, prolonged fasting slows metabolism and can negatively impact nail growth.
Frequently Asked Questions About the Link Between Nail Health and Aging
Q: How do my nails indicate how well I am aging?
A: Your nails provide a reflection of your current aging process. Research shows that nail growth slows by about 0.5% per year, and by the time you reach 100, your nails grow 50% slower than they did in your 20s. If your nails have become brittle, slow-growing or thickened, it indicates poor circulation, nutritional deficiencies or metabolic imbalances affecting your overall health.
Q: What causes my nails to become brittle and develop ridges as I age?
A: Aging nails lose their flexibility and strength due to changes in keratin structure, reduced blood circulation, and nutrient imbalances. Studies show that calcium levels in nails increase while iron levels decrease, making them more prone to cracking and splitting. Additionally, the nail bed thickens with age, reducing elasticity and slowing growth. Longitudinal ridges are often linked to deficiencies in key nutrients such as biotin, magnesium and iron.
Q: How can I improve my nail growth and strength naturally?
A: Improving circulation, optimizing nutrient intake and avoiding harmful dietary and environmental factors are key to maintaining strong nails. Keeping your hands and feet warm, staying active and avoiding smoking boost blood flow to your nails. Boosting collagen, biotin and iron levels help reinforce nail structure. Avoiding excessive water exposure, harsh nail products and toxic vegetable oils further protects your nails from damage.
Q: Are there any lifestyle habits that speed up or slow down nail growth?
A: Habits that improve circulation, such as typing, playing instruments and regular exercise help sustain healthy nail growth. On the other hand, smoking, exposure to cold temperatures and poor diet slow nail growth by restricting blood flow and reducing nutrient absorption. If you’ve noticed your nails growing slower than usual, adjusting these habits can make a difference.
Q: Why do my toenails get thicker with age, while my fingernails become more brittle?
A: Thickened toenails, a condition called onychauxis, occur due to increased keratin buildup from pressure, friction and reduced circulation in the feet. Fingernails, on the other hand, are more exposed to hydration-dehydration cycles, chemical damage from soaps and nail products and nutrient depletion, making them more brittle over time.
Strengthening both requires improving circulation, consuming nutrient-dense foods and reducing exposure to damaging chemicals and environmental stressors.
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