Several studies have shown that people who have higher levels of serum vitamin D have lower rates of colorectal cancer.
Vitamin D is a fat soluble vitamin that aids in the absorption of nutrients, promotes immune function, and maintains cell communication throughout the body. While vitamin D can be obtained from certain foods, it is also produced naturally when the body is exposed to sunlight.
Vitamin D was first identified as a potential preventive agent for colorectal cancer over twenty years ago. Researchers observed that individuals in the northern and northeastern United States had significantly higher mortality rates from colorectal cancer than those who lived in Hawaii, Florida and southwestern states. These figures were directly correlated with individuals’ serum vitamin D levels.
A more recent meta-analysis, which included data from five observational studies, found that increasing serum vitamin D levels to 34 ng/ml could reduce colorectal cancer incidence rates by half. Increasing serum vitamin D levels even higher produced greater colorectal cancer preventive benefits. Lead researcher Edward Gorham, Ph.D. explained, “We project a two-thirds reduction in incidence with serum levels of 46 ng/ml, which corresponds to a daily intake of 2,000 IU of vitamin D3. This would be best achieved with a combination of diet, supplements and 10 to 15 minutes per day in the sun” (Source: Johns Hopkins Medicine).
Experts vary in their recommendations for daily vitamin D allowance. However, current guidelines by The Institute of Medicine recommend 600 IU daily for adults between the ages of 19 and 70. Adults over the age of 70 need 800 IU daily.
To meet your daily recommended intake of vitamin D, try to spend at least a few minutes outside soaking up the sun’s rays. Vitamin D production can vary based on season, location, weather conditions, skin tone, and sunscreen use, but estimates show that just 10 to 15 minutes of sun exposure to the arms and legs can produce 3,000 to 20,000 IU of vitamin D (Source: sunshinevitamin.org). You can also increase your vitamin D intake by consuming foods that are naturally rich in this nutrient. These include:
- Fatty fish such as salmon, tuna, mackerel, and sardines
- Beef liver
- Egg yolks
- Shitake mushrooms
- Cod liver oil
- Vitamin D fortified foods including milk, cheese and orange juice