Verdict: Mostly accurate, but it oversimplifies and overstates some points.

Here’s a fact check:

What is well supported

• Vertical nail ridges (running from the cuticle to the tip) are very common and often become more noticeable with age. They are usually harmless.
• Nutritional deficiencies can contribute to nail changes in some people. Deficiencies in iron, vitamin B12, folate, zinc, and protein are more commonly linked to nail abnormalities than vitamin A alone.
• Some medical conditions (such as eczema, psoriasis, thyroid disease, kidney disease, diabetes, or inflammatory conditions) can be associated with nail changes, although ridges alone are not enough to diagnose these conditions.
• Seeing a healthcare professional is appropriate if nail changes are new, severe, or accompanied by other symptoms.

What is misleading or overstated

• “Ridges mean you’re low in vitamin A, protein, calcium, or iron.”
  This is too simplistic. Most nail ridges are not caused by nutritional deficiencies. A doctor would consider your overall health, diet, medications, and other symptoms before suspecting a deficiency.
• “Deep ridges may indicate kidney disease or diabetes.”
  Nail changes can occur with chronic illnesses, but ridges by themselves are not a reliable sign of kidney disease or diabetes. Those conditions are diagnosed using medical history, examination, and laboratory tests—not nail appearance alone.

When to see a doctor

Consider medical evaluation if you notice:

• A sudden change in one or more nails
• Deep horizontal grooves (called Beau’s lines), especially if they appear suddenly
• Nails that become very brittle, thickened, distorted, or separate from the nail bed
• Dark brown or black streaks that weren’t caused by an injury
• Redness, swelling, pain, pus, or warmth around the nail
• Nail changes along with symptoms such as fatigue, weight loss, numbness, or other unexplained health problems

What you can do

• Eat a balanced diet with enough protein, iron, and other essential nutrients.
• Keep nails moisturized if they’re dry or brittle.
• Avoid frequent trauma, picking, or harsh chemicals.
• Stay hydrated, although dehydration alone is not a common cause of nail ridges.

Bottom line

Most vertical ridges are a normal part of aging and aren’t a cause for concern. While nutritional deficiencies and certain medical conditions can sometimes affect the nails, ridges alone rarely indicate a serious illness. If nail changes are sudden, severe, or accompanied by pain, discoloration, or other symptoms, it’s a good idea to have them evaluated by a healthcare professional.