Do you bruise easily? Why this common sign could be a brain health warning after 40

Nutritionist Estefanía Álvarez has some staggering statistics: of every ten patients who walk into her clinic, seven are deficient in vitamin K.

She describes the generally less talked-about vitamin as essential for everything from blood clotting to calcium regulation. In short, it’s the key to a healthy heart and strong bones – but its benefits don’t stop there. 

Vitamin K is also instrumental in warding off heart attacks, strokes, and type 2 diabetes, while protecting against bone fractures, Alzheimer’s disease and the general wear and tear of ageing. 

The ‘hidden’ vitamin K sources: From leafy greens to fermented fridge staples   

The good news is that you can obtain the nutrient naturally through food. “There are two distinct forms [of the vitamin],” details clinical nutritionist Elisa Blázquez.

“You’ll find vitamin K1 in abundance in green leafy vegetables, such as spinach, chard, broccoli, kale or parsley. Vitamin K2 is found in fermented foods like natto (fermented soy) and mature cheeses, as well as grass-fed butter, egg yolks, and organ meats like liver. 

“While K1 is vital for healthy blood clotting, K2 is the real hero for your heart and bones.”

5 ways vitamin K protects your body after 40

Before we look at the warning signs of deficiency, let’s break down exactly what vitamin K can do for your health: 

1. It protects against ‘stiff’ arteries (heart attack and stroke). 

Essentially, if your vitamin K levels are topped up, your arterial health will be significantly better, especially once you hit 40. But why? “Without enough vitamin K2, calcium can settle in the arteries rather than being directed to the bones,” explains Blázquez. “This encourages atherosclerosis, increasing the risk of heart disease and strokes.” 

In fact, its perfect partner is vitamin D: “Many vitamin D supplements now come with added vitamin K,” notes Álvarez. “While vitamin D helps the body absorb calcium, vitamin K ensures that calcium actually reaches the bones instead of lingering in the arteries.” 

2. It helps ward off type 2 diabetes.

Vitamin K helps regulate our insulin sensitivity and metabolises glucose (sugar) so we can use it for energy rather than letting it build up in the bloodstream, reducing the risk of type 2 diabetes. “Studies suggest that healthy levels of vitamin K2 can improve the function of the pancreas’ beta cells, which produce insulin,” says Blázquez. She also highlights its anti-inflammatory benefits, which help reduce insulin resistance. 

3. It helps protect against fractures and osteoporosis.

“Vitamin K activates a protein called osteocalcin, which ‘glues’ calcium to the bone matrix,” says nutritionist Álvarez. “This is a crucial step in preventing osteoporosis and bone fractures.” In fact, its role in bone density is so significant that some countries already include it in official treatments to help improve quality of life and prevent breaks in older patients.

4. It may lower risk of neurodegenerative diseases. 

Several studies have linked low vitamin K levels to a higher risk of cognitive decline. Thanks to its potent anti-inflammatory and antioxidant properties, it helps keep the brain sharp. “It’s essential for the synthesis of sphingolipids – fats that are fundamental for healthy brain cell structure,” says Blázquez. By protecting neurons from oxidative damage, vitamin K may help stave off diseases like Alzheimer’s and Parkinson’s.

5. It can protect against cellular ageing.

As an antioxidant, vitamin K fights off the free radicals and inflammation that lead to oxidative stress. “This stress plays a major role in cell deterioration, loss of skin elasticity and other age-related conditions,” Blázquez points out. “By maintaining good levels of vitamin K, you are effectively supporting cellular longevity.” 

Is your bruising a warning sign? How to spot a vitamin K deficiency

You can’t always check your vitamin K levels with a standard blood test. “Because concentrations are so low, they tend to fluctuate based on your diet, gut health and liver metabolism,” warns nutritionist Blázquez. “Plus, because the vitamin is stored in the liver and fatty tissue, it’s harder to detect in the bloodstream.”

So, how can you tell if you’re running low? According to Álvarez, you should keep an eye out for these tell-tale signs: 

• Frequent bruising
• Cuts that take a long time to stop bleeding 
• Bone weakness 

Who should take a vitamin K supplement?

It’s important to note that any decision to supplement should be made by your GP on a tailored, case-by-case basis. It also comes with specific contraindications: “While it’s safe for most people, it can interfere with certain blood-thinning medications like warfarin,” warns Blázquez. “Because vitamin K helps blood clot, it can counteract the effect of anticoagulants.”

That said, a daily dose of between 90 and 120 mcg (micrograms) might be recommended for those with osteoporosis, cardiovascular issues, or insulin resistance. It’s also worth considering “if you’ve been on a long course of antibiotics, as these can hinder your body’s ability to absorb the vitamin,” Blázquez adds.

You may also need a boost if you have digestive issues that affect how you process nutrients. “Conditions like IBD (Inflammatory Bowel Disease), Crohn’s, or IBS can disrupt the absorption of vital vitamins and minerals,” explains the nutritionist. 

Finally, because vitamin K is fat-soluble, it’s best taken alongside healthy fats – such as a drizzle of olive oil, nuts, or avocado – to ensure your body can actually use it.  

About the experts:

• Estefanía Álvarez is a clinical nutritionist and health researcher specialising in metabolic health, weight management, and the use of nutrition to prevent chronic disease. 
• Elisa Blázquez is a leading clinical and integrative nutritionist specialising in anti-inflammatory diets, hormonal health, and the use of personalised nutrition to treat chronic conditions and promote long-term well-being.