Alli is the over-the-counter version of the weight-loss drug orlistat, which is available by prescription in a higher-strength product named Xenical. Alli contains 60 mg orlistat per dose, but Xenical has 120 mg. Orlistat is indicated for treating obesity in people with additional serious health risks such as diabetes or high blood pressure, according to Drugs.com. Alli can be one part of a weight-loss program including exercise and a reduced-calorie, low-fat diet. Consult with your health-care provider before taking this medicine.
Function
The enzyme lipase helps break down dietary fat in the digestive tract so the body can absorb it. Orlistat is classified as a lipase inhibitor, and by inhibiting this enzyme, it prevents your body from absorbing some of the fat you eat, explains MayoClinic.com. The undigested fat travels through the intestines and is eliminated through bowel movements. This helps some people lose weight.
Types
Because Alli prevents fat absorption, it can also prevent your body from absorbing fat-soluble vitamins. These include vitamins A, D, E and K, as well as beta carotene. Fat-soluble vitamins are stored in the liver and fatty tissues for later use, explains the Colorado State University Extension. Because of the storage aspect, serious deficiencies might not occur, but mild deficiencies are likely if you do not obtain enough of these vitamins while taking Alli.
You must replace the water-soluble B-complex and C vitamins regularly because the body eliminates any excess.
Significance
A study published in the July 2002 issue of "Pharmacotherapy" examined the effects of orlistat on fat-soluble vitamin absorption in 17 obese adolescents. Participants took 120 mg of orlistat three times per day, along with one multivitamin per day. During three to six months of treatment, vitamin E absorption was significantly reduced, and vitamin A was reduced but not significantly. Vitamin D levels dropped significantly after one month. The orlistat dosage in the experiment was higher than the recommended Alli dosage, which is 60 mg three times per day.
Vitamin K Considerations
Drugs.com notes that vitamin K levels tend to decrease in patients taking orlistat. This is an important consideration for people taking warfarin and certain other anticoagulant medications, as these drugs interact with vitamin K. Vitamin K helps blood to clot, but warfarin inhibits coagulation by antagonizing the activity of vitamin K. If you take an anticoagulant medicine and also take Alli, your doctor should monitor your blood levels closely.
Solution
Because Alli decreases fat-soluble vitamin absorption, you should take a daily multivitamin while using Alli to counteract these effects, advises the U.S. National Institutes of Health at its MedlinePlus website. Read the label to make sure it contains the fat-soluble vitamins A, D, E, K and beta carotene. Take the vitamin supplement at least two hours before or after you take Alli, or take it at bedtime.
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