If you're lactose intolerant, you experience uncomfortable digestive symptoms upon consuming dairy because you can't digest milk sugar. As a result, you may eat very little dairy or avoid it entirely. While lactose intolerance can't make you deficient in vitamin B-12 on its own, it can contribute if it causes you to avoid dairy entirely.
Lactose Intolerance
Lactose intolerance results from insufficient production of lactase, which is the enzyme your small intestine uses to digest milk sugar. Lactose is made up of two smaller sugar units called glucose and galactose, explain Drs. Reginald Garrett and Charles Grisham in their book "Biochemistry." You have to break lactose into these smaller units to absorb it. If you don't produce lactase, you can't absorb lactose, and it's digested by bacteria in your large intestine. This leads to symptoms such as bloating.
Vitamin B-12
Vitamin B-12 is one of the micronutrients that you need to take in small amounts to maintain health. Micronutrients include vitamins and minerals. They don't provide energy, but they're critical to cellular function. Specifically, you need vitamin B-12 to maintain the nervous system and to help produce blood cells, explains Dr. Lauralee Sherwood in her book "Human Physiology." Deficiencies in the vitamin lead to fatigue, memory loss and psychological symptoms but usually only arise after many years of vitamin B-12 deprivation.
Sources of B-12
Vitamin B-12 is widely available in food, though almost all of its sources are non-vegetarian. You can get it in meat, dairy and eggs. If you're not a vegetarian, you won't have a problem with vitamin B-12 deficiency, even if your lactose intolerance leads you to avoid dairy. If you're a lacto-ovo vegetarian, meaning you accept the consumption of milk and eggs, you can substitute eggs for dairy to get your B-12.
Alternatives
If you don't eat meat or eggs and would be willing to drink milk but are lactose intolerant, there are some alternatives available to you that can help you get your dairy -- and your vitamin B-12. Lactose-free milk has the vitamin B-12 intact but doesn't contain lactose. Alternately, you can consume regular dairy and also take lactase supplements. These supplements will allow you to digest the lactose in a given meal and prevent gastric symptoms.
References
- "Biochemistry"; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
- "Human Physiology"; Lauralee Sherwood, Ph.D.; 2004
