8. Thiamine B1
Also known as thiamin, vitamin B1 plays a number of roles in the body, including the metabolism of carbohydrates (26).
Thiamine deficiency affects both the central and peripheral nervous systems, not to mention almost every organ. In fact, most people diagnosed with congestive heart failure also have a thiamine deficiency (27).
The reference range for a B1 blood test is between 2.5-7.5 µg/dL. The recommended daily intake for B1 is around 1.1 mg for the average adult (28). Thiamine-rich foods include whole grains, leafy and dark colored vegetables, legumes, and animal meats/products.
9. Vitamin K2
K2 is a lesser known and understood vitamin (compared to others on this list), but new research shows that it is just as important (29).
As it turns out, vitamin K2 aids the body in metabolizing calcium to protect the coronary arteries and blood vessels. This is an important finding for those susceptible to coronary occlusions or at risk for ischemic heart disease (30).
Discuss your vitamin K intake with your doctor if you are on blood thinners, as it can cause interactions (31, 32).
A fat-soluble vitamin, K2 is found naturally in grass-fed dairy products and eggs. The recommended daily intake for vitamin K is approximately 120 mcg for men and 90 mcg for women (33).
The reference range for a normal vitamin K blood test is between 0.2-3.2 ng/mL. Since vitamin K is not easily absorbed, it is recommended to aim for more than these amounts in your diet.