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Low Alkaline Phosphatase Symptoms, Causes & Meaning

Written by Puya Yazdi, MD | Last updated:
Medically reviewed by
Ana Aleksic, MSc (Pharmacy), Evguenia Alechine, PhD (Biochemistry) | Written by Puya Yazdi, MD | Last updated:

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Most people worry about high alkaline phosphatase, but low levels can also signal health problems. People who don’t get enough magnesium, zinc, and protein are more likely to have low alkaline phosphatase. Read on to finally understand what low results mean.

What Does Low Alkaline Phosphatase Mean?

The normal range of alkaline phosphatase in the blood is 20 to 140 U/L, although this can vary from lab to lab. Some labs set the range at 30 to 130 U/L. Children and pregnant women can have significantly higher levels of the enzyme in their blood [1].

Values under 30 U/L are usually considered low.

Alkaline phosphatase (AP) is an enzyme found in all tissues in the human body but is mostly concentrated in the bones, kidneys, liver, intestines, and placenta. It exists in different forms, depending on where it originates [1].

We have been long aware of tissue Alkaline Phosphatase and its major role in bone health, and bone calcification. Yet, promising research on intestinal AP is increasingly supportive of its protective role on the intestinal tract aiding the balance of bacteria, digestion, and the breakdown of fats and some B vitamins. [1].

Alkaline phosphatase below 30 U/L is considered low by most labs.

Symptoms of Low Alkaline Phosphatase

Low levels of ALP may stem from other conditions such as B12 deficiency and hypothyroid. When this is the case and depending on the cause of the low ALP levels, you may experience symptoms like:

  • Headache, breathlessness, and fatigue (if you have B12 deficiency and anemia) [2]
  • Weight gain, muscle weakness, and dry skin (if you have hypothyroidism) [3]
Symptoms of low alkaline phosphatase depend on the underlying health condition — such as anemia or an underactive thyroid.

Causes of Low Alkaline Phosphatase

1) Wilson’s Disease

Wilson’s disease is an inherited disorder where copper is accumulated in the organs. Wilson’s disease patients have low blood alkaline phosphatase activity. They also had a significantly lower alkaline phosphatase to bilirubin ratio [4].

3) Malnutrition

Malnutrition can also cause lowered alkaline phosphatase levels in the blood. In a review of 130 patients with low enzyme levels, 12% suffered from malnutrition [5].

4) Magnesium Deficiency

Magnesium deficiency can lower alkaline phosphatase activity levels in the body because The enzyme needs magnesium to activate. In a study done on female rats, the rats with a magnesium-deficient diet had only half the alkaline phosphatase activity compared to the controls. A study shows magnesium supplementation significantly restores enzymatic activity but does not return AP to normal levels [6].

5) Zinc Deficiency

Zinc deficiency lowers alkaline phosphatase activity in animals. People with zinc deficiency are more likely to have low alkaline phosphatase and a range of other associated health problems. Supplementing with zinc restored normal alkaline phosphatase levels in one clinical study [7, 8].

6) Protein-Free Diet

Rats fed a protein-free diet have reduced intestinal alkaline phosphatase activity [9].

People who don’t get enough zinc, magnesium, protein, or calories are at risk of low alkaline phosphatase.

7) Certain Drugs

The following drugs can also cause low ALP levels:

  • Cinacalcet (a drug that lowers calcium in the blood) [10]
  • Oral contraceptives [11]
  • Hormone replacement therapy [12]

Other Conditions

Low ALP can also be caused by:

Additionally, low levels of alkaline phosphatase are present in hypophosphatasia, an inherited disorder that causes defective bone mineralization. Without the enzyme, children can have an early loss of teeth and seizures while adults can have dental problems and weakened bones [16].

Achondroplasia is a type of dwarfism, and cretinism is a condition with severely stunted growth. In children with these disorders, their alkaline phosphatase levels are lower than the normal range [17].

Check your thyroid hormones, cortisol, and vitamin D and B12 levels. Megadosing vitamin D, low thyroid hormones, anemia, and high cortisol can lower alkaline phosphatase.

Benefits of Lower Alkaline Phosphatase compared to Higher

1) Better Attention and Memory

In obese individuals with elevated alkaline phosphatase, a decrease in levels post-surgery predicted better scores on a brain test in patients who have undergone weight loss surgery. This suggests that a lower level of enzyme activity can predict better attention and memory abilities. However, the brain needs some alkaline phosphatase for optimal function [18].

2) Lower Cholesterol

Pregnant women have higher blood alkaline phosphatase activity. Both triglyceride and total cholesterol levels increased in parallel with alkaline phosphatase, so cholesterol levels are correlated with enzyme activity [19].

Normal alkaline phosphatase levels support good health. Slightly lower values may improve cognition and have been linked with lower cholesterol levels.

How Alkaline Phosphatase Levels Can Be Restored?

If your alkaline phosphatase is low, you need to seek medical attention for an underlying condition. People with low alkaline phosphatase due to genetic disorders or serious medical conditions need to receive a treatment plan from their healthcare provider.

Correct Nutritional Deficiency

If your ALP levels are low due to a nutritional deficiency, correct the underlying nutritive cause. Eat more foods rich in:

  • Protein, such as dairy products, meat, poultry, beans, eggs, fish, and nuts and seeds [20]
  • B vitamins, such as meat, fish, leafy vegetables, beans, grains, dairy products, and eggs [21, 22]
  • Zinc, such as meat and poultry, cereals and cereal products, and milk products [23]
  • Magnesium, such as green leafy vegetables, fruits, grains, and nuts [24]
Focus on correcting the nutritional deficiency that is lowering your alkaline phosphatase levels. Get enough protein, B vitamins, zinc, and magnesium.

Check Your Medications & Thyroid Hormones

Excess vitamin D in your body can cause low ALP levels. Though it often takes a very large dose of supplemental Vit D to see this change, consider stopping the supplement when measured vitamin D levels are significantly high. Instead, get more sun [13].

If your medications are likely to lower ALP levels, discuss alternative options with your doctor [11].

Get your thyroid hormones checked [25]. This is a common reason for abnormal AP levels.

Look to resolve thyroid issues, don’t take vitamin D megadoses, and talk with your doctor about medications that may be lowering your alkaline phosphatase levels.

Lifestyle & Supplements

Moderate to intensive exercise can transiently increase ALP levels [26, 27].

Supplements that may help:

  • Protein [28]
  • Vitamin B12 (if deficient) [29]
  • Magnesium (if deficient) [30]
  • Zinc (if deficient) [31]


Low alkaline phosphatase is when your blood levels are under 30 U/L (lab dependent). Your body needs just the right amount of alkaline phosphatase to keep your gut, brain, and bones healthy. Low levels can suggest zinc, magnesium, or protein deficiency. People who consistently take high vitamin D doses or certain medications are also more likely to have low levels of this enzyme. Other possible causes include an underactive thyroid, anemia, and genetic disorders. Work with your doctor to discover what is lowering your levels. The goal should be to address nutrient deficiencies, thyroid issues, or any other underlying health problems you may have.

Further Reading

About the Author

Puya Yazdi

Dr. Puya Yazdi is a physician-scientist with 14+ years of experience in clinical medicine, life sciences, biotechnology, and nutraceuticals.
As a physician-scientist with expertise in genomics, biotechnology, and nutraceuticals, he has made it his mission to bring precision medicine to the bedside and help transform healthcare in the 21st century. He received his undergraduate education at the University of California at Irvine, a Medical Doctorate from the University of Southern California, and was a Resident Physician at Stanford University. He then proceeded to serve as a Clinical Fellow of The California Institute of Regenerative Medicine at The University of California at Irvine, where he conducted research of stem cells, epigenetics, and genomics. He was also a Medical Director for Cyvex Nutrition before serving as president of Systomic Health, a biotechnology consulting agency, where he served as an expert on genomics and other high-throughput technologies. His previous clients include Allergan, Caladrius Biosciences, and Omega Protein. He has a history of peer-reviewed publications, intellectual property discoveries (patents, etc.), clinical trial design, and a thorough knowledge of the regulatory landscape in biotechnology. He is leading our entire scientific and medical team in order to ensure accuracy and scientific validity of our content and products.


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