Inositol

Why inositol is good for you

Inositol is one of the B vitamin co-factors. It assists the B vitamins to function more effectively.

Inositol can be either obtained from foods eaten, or the body can create it. The food source of inositol is obtained from plant-based foods from phytic acid – a substance found in the fibre of foods and the body converts this into inositol in the intestines, where it is absorbed. Inositol is also found in the form myo-inositol in some foods, which does not need to be converted and can be absorbed and used directly by the body for its various functions.

Inositol plays an important part in the health of cell membranes especially the specialised cells in the brain, bone marrow, eyes and intestines. Cell membranes are responsible for regulating the contents of the cells, to enable the cells to function correctly.

Inositol promotes healthy hair and hair growth, and it also helps in controlling oestrogen levels.

Important inositol facts

• Inositol is a water-soluble vitamin, which means that it is easily absorbed in the body (as most of the body is made of water and so are most of the foods eaten).
• Some of it may be lost in cooking
• Inositol is needed for health at cellular level
• Inositol is found in plentiful supply in the lens of the eye, as well as the heart, but it is also concentrated in other parts of the body too
• Inositol is a B vitamin co-factor, which means it is not quite a vitamin, but works with all of the B vitamins to help them perform their activities more effectively
• Inositol is closely related to choline – in fact the two work together to make neurotransmitters and the fatty substances for cell membranes, as well as helping to metabolise and move out fats from the liver
• Inositol works closely with another B-vitamin co-factor (choline) as well as with vitamin H (biotin) to help turn the food that is eaten, into energy for the body, through the process of digestion. Inositol also works closely together with choline to maintain and regulate cell membranes
• Inositol is obtained from food in two ways: (1) from phytic acid – a substance found in the fibre of foods (phytic acid gets converted to inositol in the intestine); and (2) from foods directly in the form of myo-inositol

Inositol works best with

• Choline
• Essential fatty acids
• Folic acid
• Vitmin B3
• Vitamin C
• Cysteine
• Cystine
• Tryptophan

Inositol and health

• Reversing hair Loss
  Men taking extra inositol reported that their hair loss had improved, with less hair falling out – although this has not been tested under clinical situations.
• Reducing LDL cholesterol
  Inositol may be of benefit in reducing blood cholesterol levels.

Talk to a medical professional about inositol supplements before taking them.

Groups at risk of inositol deficiency

Inositol deficiency is rare, because the body can make its own inositol if it is not obtained in the diet. The only people who may be at risk of inositol deficiency are:

• Alcoholics
  People who drink excessive amounts of alcohol may have reduced absorption of many nutrients, not just inositol
• People taking certain medications
  People taking certain medications may have reduced levels and effectiveness of inositol, as some medications block its absorption, so supplementation could be required
• People who are taking antibiotics
  People taking antibiotics may not be absorbing inositol (nor the other B vitamins or the co-factors) and could need supplementation, especially if the antibiotic use is long term
• People who are under prolonged stress
  People who are under prolonged stress will be using up their inositol (and the other B vitamins or the co-factors) at a much faster rate, so supplementation could be required
• People who drink a lot of coffee
  People who drink copious amounts (more than 3 cups) of coffee each day may have reduced levels and effectiveness of inositol, as high intake of caffeine can block inositol’s absorption, so supplementation may be needed
• People who have high blood pressure
  People with high blood pressure may have lower levels of inositol, so supplementation may be needed. The correct levels of inositol may play a part in helping to lower blood pressure
• People who have high LDLD (“bad”) cholesterol levels
  People with high LDL (“bad”) cholesterol may have lower levels of inositol, so supplementation may be needed. Inositol helps the body lower LDL (bad) cholesterol levels

Talk to a medical professional about inositol supplements before taking them.

Inositol deficiency is rare, because the body can make its own inositol if it is not obtained in the diet

Symptoms of inositol deficiency

Inositol deficiency is not very common as most people get enough from the foods in their diet.

A deficiency can occur if there is some problem with either absorption of inositol eaten or a problem with the body’s ability to make its own inositol and the following symptoms may appear.

Deficiency symptoms that do rarely occur, are:

• constipation
• eczema and other skin irritations
• elevated LDL (“bad”) cholesterol levels
• hair loss

People with any of these symptoms should seek advice from their medical practitioner to determine if inositol supplementation is warranted in their individual situation.

Inositol in food

The body is able to manufacture this co-factor nutrient.

Inositol is also available from:

• Bananas
• Brewers yeast
• Brown rice
• Liver
• Nuts
• Oat flakes
• Raisins
• Unrefined molasses
• Vegetables
• Wheat germ

Inositol recommended daily intake (RDI)

The tolerable upper limits should only be taken for short periods and only under medical supervision.

Toxicity

Inositol is essentially non-toxic, even when it is taken at high doses. The only side effects occur when doses of inositol are greater than 0.5g per kg of body weight per day. Overdosage and toxicity is more likely to occur from taking too many supplements, whereas dietary intake of inositol is highly unlikely to cause overdosage.

Overdosage and toxicity symptoms

If inositol is taken above 0.5g per kg of body weight, it can cause the following toxicity symptoms:

• Diarrhoea
• Increased secretion of creatine

People experiencing any of the above toxicity symptoms should discontinue their inositol supplements and seek medical advice.

Precautions

Certain people should not take inositol supplements at all:

• Women who are pregnant or breastfeeding
  At present, a recommended daily intake of inositol for women who are pregnant or breastfeeding has not been established, so safe levels of inositol have not been established for women who are pregnant or breastfeeding, who should instead get their inositol from foods.

Certain people should only take inositol supplements without first consulting their doctor for advice:

• People with an anxiety disorder
  People who have any type of anxiety disorder may experience a worsening of their condition if the intake of inositol supplements is high.
• People with a sleep disorder
  People that have a sleep disorder (such as insomnia) may may experience a worsening of their condition if the intake of inositol supplements is high.
• People with diabetes (and peripheral neuropathy)
  People that have diabetes, especially if they have peripheral neuropathy symptoms (tingling and pain in the extremities) need to ensure the amount of inositol taken is adequate and does not make their symptoms worse. Inositol supplementation in people with diabetic neuropathy need to be monitored while they are taking it, to determine how effective it is as a treatment for their condition.

Women who are pregnant or breastfeeding should not take inositol supplements

Interactions with medications and supplements

The following are the medications and supplements that are more likely to cause a reaction with inositol supplements:

• Antibiotics
  People taking antibiotics may have decreased absorption of inositol (and the other B vitamins and co-factors) from the foods eaten and this means there may be a requirement for supplementation with inositol, especially people taking antibiotics long term.
• d-Glucose
  People taking d-glucose may have decreased absorption of inositol (and the other B vitamins and co-factors) from the foods eaten and this means there may be a requirement for supplementation with inositol, especially people taking d-glucose long term.
• Lithium
  People taking lithium should not take inositol supplements at the same time because the inositol will increase the excretion of lithium and reduce its effectiveness.

Other interactions with inositol

Inositol also has interactions with other substances, as follows:

• Alcohol
  Alcohol decreases the absorption of inositol, so supplementation may be required.
• Tobacco
  Tobacco also reduces the absorption of inositol, so supplementation may also be required.

Inositol’s effect on lab tests

There are none.

References

• Griffith HW. Minerals, Supplements and Vitamins – The Essential Guide. 2000 Fisher Books, USA
• Lieberman S, Bruning N. The Real Vitamin and Mineral Book – Using Supplements for Optimal Health. 3rd Edition. Avery Publishing, New York, 2003
• O’Hara J, Nicol CG. The therapeutic efficacy of inositol nicotinate (Hexopal) in intermittent claudication: a controlled trial. Br J Clin Prac. 1988;42(9):377-381
• Office of Dietary Supplements USA – has the official USA RDI for all vitamins (these are also adopted by Australia), accessed 9 August 2005
• Osiecki, Henry, The Nutrient Bible 2002, BioConcepts Publishing
• Sarkar S, et al. Lithium induces autophagy by inhibiting inositol monophosphatase. J. Cell Biol, 2005. 170 (7): 1101-1111

Last reviewed and updated: 9 May 2024