People who are genetically intolerant to lactose, the main sugar found in milk and dairy products, have lower than average vitamin D levels, according to new Canadian research.
Limiting or eradicating dairy products from the diet due to lactose intolerance has been associated with lower levels of vitamin D in the blood, according to research from the University of Toronto studying 1,495 Canadian men and women aged between 20 and 29 years old.
The researchers found that people of Caucasian origin who were genetically intolerant to lactose had lower than average levels of vitamin D.
The study, published in The Journal of Nutrition, also found people who carry a gene associated with lactose intolerance, called LCT, to be slightly shorter than those who don't, suggesting an insufficient intake of vitamin D could limit bone growth.
The inability to digest lactose was found in 32% of Caucasian participants, 99% of East Asians, 74% of South Asians and 59% of mixed ethnicities, the study reports.
The researchers advise lactose-intolerant people to ensure they make up for the lack of vitamin D by eating other fortified foods or by adding lactose-free dairy products to their diets.
Produced by exposure to sunlight, vitamin D helps the body absorb calcium. Food sources include oily fish (salmon, trout, tuna, sardines and mackerel), calf's liver, soy drinks and egg yolks. Hard cheeses (cheddar, edam, gouda, gruyere), in particular, contain very low levels of lactose.
Dietary sources of vitamin D and exposure to sunlight are not always sufficient to ensure healthy levels of vitamin D. In such cases, health care professionals may prescribe supplements.
Previous research has highlighted the importance of vitamin D and its role in the prevention of cardiovascular disease, cognitive decline, autoimmune disease and cancer. It is also known for its role in bone health, protecting against osteoporosis and increasing muscle mass.