After one month, influenza infection rates in the two groups remained the same. By the second month, however, participants in the vitamin D group were 50 percent less likely to become infected than participants in the control group. This drop in infection rate corresponded with an increase in vitamin D blood levels. READ MORE.
Natural sources of vitamin D include:- Fatty fish species, such as:
- Catfish, 85 g (3 oz) provides 425 IU (5 IU/g)
- Salmon, cooked, 100 g (3.5 oz) provides 360 IU (3.6 IU/g)
- Mackerel, cooked, 100 g (3.5 oz), 345 IU (3.45 IU/g)
- Sardines, canned in oil, drained, 50 g (1.75 oz), 250 IU (5 IU/g)
- Tuna, canned in oil, 100 g (3.5 oz), 235 IU (2.35 IU/g)
- Eel, cooked, 100 g (3.5 oz), 200 IU (2.00 IU/g)
- A whole egg, provides 20 IU (0.33 IU/g if egg weighs 60 g)
- Beef liver, cooked, 100 g (3.5 oz), provides 15 IU (0.15 IU/g)
- Fish liver oils, such as cod liver oil, 1 Tbs. (15 ml) provides 1360 IU (90.6 IU/ml)
- Mushrooms are the only vegan source of vitamin D (besides UV light or sunlight exposure
