What is a Vitamin Deficiency That Causes Muscle Aches & Tiredness?

Vitamin D is most widely known for keeping the bones strong. This vitamin allows you to absorb calcium and blocks the release of parathyroid hormone, which contributes to thin and brittle bones. Vitamin D also keeps your immune system healthy and ensures proper muscle function.

The Harvard T.H. Chan School of Public Health notes that vitamin D isn't just a nutrient that you get from food; it's also a hormone that your body can make (with exposure to the sun). That's why it's so important to overall health.

Reviews in Endocrine and Metabolic Disorders in May 2017 describes vitamin D deficiency as a "pandemic" and "global health issue" whose effects "cannot be understated." According to the journal report, vitamin D deficiency affects more than one billion people worldwide. Vitamin deficiency symptoms are often nonspecific. Deficiency in vitamin D doesn't just cause uncomfortable symptoms like:

• Muscle aches and weakness
• Tiredness and chronic fatigue
• Inflammation
• Insomnia
• Depression
• Anxiety
• Increased frequency of colds and infections

It's also associated with chronic health problems, including:

• Heart disease
• Autoimmune disorders
• Cancer
• Type 2 diabetes
• Neurological disorders (multiple sclerosis)
• Cavities
• Osteoporosis and other bone diseases

Although many health experts are concerned about the widespread low levels of vitamin D, others think it's more of a problem with the numbers. The current definition of a vitamin D deficiency is a blood level that falls below 35 ng/mL. Researchers published in the New England Journal of Medicine in November 2016 consider that cutoff number is too high and, because of that, people are misdiagnosed as deficient when they're not. A report published in the Oct-Dec 2015 edition of the Indian Journal of Community Medicine agrees.

However, other practitioners, like functional medicine doctor Dr. Mark Hyman and Dr. Michael Holick, director of the Bone Health Care Clinic at the Boston University Medical Center, think that the 30 ng/mL cut off is actually too low and that higher levels may be better, reported in June 2018 in the Mayo Clinic Proceedings.

Approximately 80 to 90 percent of the vitamin D stored in your body comes from the ultraviolet rays of the sun. Because of this, inadequate exposure to sunlight, especially during the winter months, is one of the leading causes of vitamin D deficiency. People with a darker skin tone are also at a higher risk of developing vitamin D because melanin, the pigment that gives skin its color, decreases the skin's production of vitamin D.

As you age, your body's natural ability to make vitamin D decreases, so older people have a higher risk of developing a vitamin D deficiency. According to the Linus Pauling Institute at Oregon State University, older adults have a lower concentration of the vitamin D precursor in their skin, so they're unable to produce the same amount of vitamin D as younger adults, even when exposed to the same amount of sunlight. Being overweight or obese also increases your risk.

Read more: 9 Ways to Help Avoid Vitamin D Deficiency

The amount of vitamin D you need daily depends on your age. Adults under 70 should aim for 600 IU per day, while adults 70 and older need 800 IU. Although most of the vitamin D you get comes from the sun, food sources of vitamin D include:

• Swordfish
• Salmon
• Tuna
• Sardines
• Beef liver
• Egg yolk
• Fortified cereal
• Fortified milk

Cod liver oil also contains a high amount of vitamin D, approximately 1,360 IU per tablespoon).

Vitamin B12 plays major roles in keeping your nervous system and red blood cells healthy. Without enough vitamin B12, your body cannot make new, healthy red blood cells.

Your body also uses vitamin B12 to make DNA, the genetic code in all of your cells. Like all the other B vitamins, vitamin B12 also plays a role in energy production and the metabolism of protein.

Vitamin B12 deficiency is another widespread health concern in the United States that affects approximately 6 percent of people under the age of 60 and almost 20 percent of people older than 60. Because vitamin B12 deficiency can cause a wide range of symptoms, it's often misdiagnosed or overlooked. Symptoms may develop gradually or come on suddenly and can include:

• Muscle aches and weakness
• Tiredness and fatigue
• Difficulty walking
• Numbness and tingling in the extremities
• Swollen tongue
• Shortness of breath
• Irritability
• Diarrhea
• Increased heart rate

If left untreated, vitamin B12 deficiency can lead to serious anemia, or a low red blood cell count, nerve damage (and lasting muscle aches) and degeneration of the spinal cord.

Read more: The Best Method to Increase Vitamin B12 Levels

One of the most common causes of vitamin B12 is a lack of a substance called intrinsic factor. Intrinsic factor is a protein that's made and secreted by your stomach that allows you to absorb vitamin B12. Without it, proper absorption is impossible.

Other possible causes of vitamin B12 deficiency include:

• Veganism and vegetarianism
• Excessive alcohol intake
• Autoimmune disorders
• Gastritis (inflammation of the stomach lining)
• Use of oral contraceptives
• Other prescription medications (metformin, proton-pump inhibitors)
• Methylation defects
• Bariatric surgery

The current recommendation is that adults get 2.4 micrograms of vitamin B12 every day. The richest sources of vitamin B12 are animal foods like:

• Beef
• Chicken
• Fish
• Eggs
• Dairy products
• Beef liver
• Clams

Plant foods don't contain any vitamin B12 naturally, but some cereals are fortified with synthetic versions of the vitamin. This is why vegans and vegetarians have one of the highest risks of deficiency.

If you suspect you're low on vitamins, check with your doctor. Your doctor can order simple blood tests that can either confirm or rule out deficiencies. If you do have low levels of a certain vitamin (or vitamins) your doctor may recommend a supplement or refer you to a nutrition professional who can work with you to design a balanced diet that gives you all of the nutrients you need to stay healthy.

It's best to talk to a doctor or qualified health professional about your concerns and/or any supplements before you start taking them. If it's determined that your vitamin levels are due to an underlying medical issue, your doctor will work with you to correct the cause of the deficiency as well to prevent recurrence.