What do brittle nails tell you about your health?

As I’ve said before, your nails can reveal a heck of a lot about your general state of wellness, your digestion and your nutritional status.

You don’t always have to do expensive lab tests to uncover important information about how your body is working.

In the last article, we looked at the relationship between horizontal nail ridges, vitamin B1 deficiency, and symptoms such as fatigue, nausea, digestive problems and irritability.

In this one, we’re exploring some of the reasons why you might develop brittle nails – nails that crack and break easily.

In my experience, brittle nails can reflect several damaging nutrient deficiencies and digestive problems.

Brittle nails and biotin deficiency

Biotin, which is also known as vitamin H and vitamin B7, is a really important nutrient.

First of all, it is critical for optimal fetal development, which says a lot. Biotin is also really important for DNA and gene expression, which also says a lot.

It is involved with the metabolism of protein, amino acids and collagen, which is why your skin, nails and hair can be affected by biotin deficiency.

Because of its role in skin, hair and nail health, we might even call it an important “beauty nutrient”.

The picture below depicts brittle, cracked nails, which can result from biotin deficiency.

rittle nails

Other signs and symptoms of biotin deficiency

A related problem is where you get peeling and damage to the nail cuticle, as shown in the picture below.



Biotin’s role in skin, hair and nail health are confirmed when we look at some of the other symptoms of deficiency:

  • Hair loss and alopecia
  • Dermatitis and skin rash
  • Mild anemia
  • Difficulty balancing (ataxia)
  • Seizures

We’re more concerned with the subtle symptoms here, as things like seizures obviously require medical attention.

Food sources of biotin

Two forma of biotin are found in food:

  1. Free biotin found in plants
  2. Protein-bound biotin found in animal foods

Your body has the ability to use either of these forms, however the free version is more readily absorbed as it does not need to be converted into a bioavailable form.

Foods high in free biotin include:

  • Sunflower seeds
  • Green peas and lentils
  • Walnuts and pecans
    • Nuts, seeds, grains and legumes can be irritating to the digestive tract, which may make them poor choices for some people
  • Carrots, cauliflower and mushrooms
  • Avocados

Protein-bound biotin is found in the following foods:

  • Organic, free-range/pastured eggs yolks (one of the very best biotin sources)
  • Organ meats such as liver and kidneys
  • Dairy products such as milk, butter and cheese (ideally organic raw milk from grass-fed cows)
    • Dairy products can be very problematic for some folk
  • High quality seafood

Interestingly, eating raw eggs can lead to biotin deficiency because a protein called avidin in the egg white actually interferes with biotin absorption. Cooking the egg white resolves this problem.

Gut bacteria produce biotin

Your gut bacteria are quite efficient at producing certain vitamins and it has been suggested that low friendly bacteria levels may contribute to nutrient deficiencies.

Biotin is one of the nutrients produced by gut bacteria (others include B12,  B6, folate and vitamin K).

“Taken together, these findings show that the majority of Bacteroidetes, Fusobacteria, and Proteobacteria genomes contain the essential roles for biotin biosynthesis.


How do biotin deficiencies develop?

As with all nutrient deficiencies, the usual suspects combine to produce biotin deficiency…

  • Excess usage by the body due to stress
  • Inadequate intake due to poor diet
  • Inadequate digestion and absorption

Furthermore, if the friendly bacteria levels in your gut are not optimal, you may also find yourself deficient in biotin and other B vitamins.

Thus, when thinking about poor nail health, hair loss and skin problems, it’s really, really important to consider your digestive health.

Lab tests for biotin deficiency

Unlike some of the other B vitamins, and nutrients such as vitamin D, it’s not easy to test biotin levels.

This is because there aren’t any ways (to my knowledge) that you can directly measure biotin in the blood. Thus, doctors simply don’t consider it.

The most reliable indicators of biotin status are impossible to pronounce…

  • Reduced propionyl-CoA carboxylase activity in peripheral blood lymphocytes
  • Reduced levels of holo-methylcrotonyl-CoA carboxylase and holo-propionyl-CoA carboxylase in lymphocytes.

Nonetheless, despite these silly long words, biotin status can be checked with functional medicine testing. And you can do it at home.

Organic acids test (simple home urine test)

An excessively high urinary level of another unpronounceable chemical – β-Hydroxyisovalerate – is a great indicator of biotin deficiency.

It’s an easily accessible test. You can do it at home along with 70+ other markers in the organic acids test.

It’s the best starting point if you want to check your biotin level.

Stool Testing

How could a stool test provide information about biotin levels (or any other nutrient, for that matter)?

Well, it’s not about measuring the nutrient per se. Instead, it’s about assessing whether you can digest food and absorb nutrients properly.

If your stool test shows weakened digestion, and/or lots of inflammation in your gut, then you need to fix this first.

There’s no point taking expensive supplements if you’re just going to poop them out.

Furthermore, a stool test is going to give you insight into your good bacteria levels.

If these friendly bacteria levels are low, it’s very much worth taking appropriate action steps to top them up and maintain a healthy gut microbiome.

After all, they make biotin and other nutrients for you.

Research findings on biotin supplementation for brittle nails

Studies support the use of biotin supplementation in restoring nail health. A review at Oregon State University’s Micronutrient Information Center has summarised these studies.

“The finding that biotin supplements were effective in treating hoof abnormalities in hoofed animals suggested that biotin might also be helpful in strengthening brittle fingernails in humans. Three uncontrolled trials examining the effects of biotin supplementation (2.5 mg/day for several months) in women with brittle fingernails have been published. In two of the trials, subjective evidence of clinical improvement was reported in 67%-91% of the participants available for follow-up at the end of the treatment period. One trial that used scanning electron microscopy to assess fingernail brittleness reported less fingernail splitting and a 25% increase in the thickness of the nail plate in patients supplemented with biotin for 6 to 15 months.”


In my opinion, while supplementation seems to be effective, I think it’s much more important to make sure you deal with the underlying reasons why biotin deficiency may have developed.

This usually means correcting your diet and optimising your digestive health.


Where to start

I realise all this information can be a little confusing, so let’s simplify.

First, check your nails – do they have horizontal ridges? Indeed, do they peel and crack easily?

If so, something is going on.

Look at your diet.

Clean it up.

Eat less processed food and more whole, unprocessed natural food (organic if possible, as you will get more nutrients into your body this way).

Regarding lab testing, it’s going to depend on your individual situation.

If you experience digestive symptoms such as heartburn, acid reflux, bloating, constipation, loose stools, gas, etc. then a stool test is the best starting point.

If your digestion feels pretty good, then having someone interpret your blood work in detail (more detail than just a medical interpretation) is a great starting point.

If you’re not feeling well, do something, because doing nothing isn’t going to resolve a damned thing and the solution could be really simple.

Our job is to help you get better, sooner, so if you’d like some assistance to cut through the noise and confusion, consider one of the options below.

Click here if you’d like more about getting stool test done, or to order one.

Click here if you’d prefer to schedule a 60min consultation where we can review your case and help you plot a course of action.

Whatever you do, don’t do nothing, and remember that the path to optimal health may be simpler than you think.

All my best,