Vitamin D

Vitamin D information, FAQ and product listing page. This page contains everything you need to know about vitamin D.

What is vitamin D and what does it do?

Vitamin D is a fat soluble vitamin, essential for the maintenance of calcium metabolism. By itself, vitamin D is biologically inactive, meaning it must be metabolized to its biologically active forms. Once introduced to the body (by way of consumption or synthesis), it goes into circulation throughout our bodies and helps with a plethora of bodily functions including the maintaining of calcium balance, cell differentiation, regulation of the immune system, and the controlling of blood pressure.

Calcium balance - Vitamin D is critical for efficient utilization of calcium by the body. Vitamin D maintains the serum calcium levels, which is not only important for the functioning of the central nervous system, but for bone growth and maintenance of bone density. (1)

Immunity - Vitamin D is a very strong immune system modulator. There is strong scientific evidence that vitamin D has a variety of beneficial effects on the immune system and it’s functioning, which can inhibit the development of auto immunities. (2)

The regulation of blood pressure is controlled partly by the rennin-angiotensin system. This system requires both renin and angiotensin to function properly. Studies have shown that inadequate levels of vitamin D have decreased these components, hence decreasing the risk of high blood pressure in those that are taking their recommended daily allowance of vitamin D. (3)

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What foods contain vitamin D?

Vitamin D is found naturally in only a select amount of foods. Foods that contain vitamin D consist of some fatty fish (salmon, sardines), fish oils, and eggs from hens that have been injected with vitamin D. Milk and infant formula in the United States are fortified with vitamin D. While these contain about 10 mcg per quart, other dairy products like cheese and yogurt may not. Other items containing vitamin D are bread, orange juice, and some cereals.

Food Serving Vitamin-D-(IU) Vitamin-D-(mcg)
Pink salmon, canned 3 ounces 530 13.3
Sardines, canned 3 ounces 231 5.8
Mackerel, canned 3 ounces 213 5.3
Quaker Nutrition for Women Instant Oatmeal 1 packet 154 3.9
Cow's milk, fortified with vitamin D 8 ounces 98 2.5
Soy milk, fortified with vitamin D 8 ounces 100 2.5
Orange juice, fortified with vitamin D 8 ounces 100 2.5
Cereal, fortified 1 serving (usually 1 cup) 40-50 1-1.3
Egg yolk 1 large 21 .53

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What is the suggested intake of vitamin D?

In 1997, the Food and Nutrition Board of the Institute of Medicine, the organization that creates the Recommended Dietary Allowances (RDAs) concluded that due to sunlight exposure having an effect on vitamin D levels on one’s body, it was impossible to make an RDA for vitamin D.

Because of this, the adequate intake levels assume that no vitamin D is being synthesized in the skin by the sun’s ultraviolet rays. With this taken into consideration, please note that the following adequate intake levels reflect only vitamin D that is consumed, not synthesized. (5)

Adequate Intake (AI) for Vitamin D:

Life Stage Age Males|mcg/day Females|mcg/day
Infants 0-6 months 5 mcg (200 IU) 5 mcg (200 IU)
Infants 7-12 months 5 mcg (200 IU) 5 mcg (200 IU)
Children 1-3 years 5 mcg (200 IU) 5 mcg (200 IU)
Children 4-8 years 5 mcg (200 IU) 5 mcg (200 IU)
Children 9-13 years 5 mcg (200 IU) 5 mcg (200 IU)
Adolescents 14-18 years 5 mcg (200 IU) 5 mcg (200 IU)
Adults 19-50 5 mcg (200 IU) 5 mcg (200 IU)
Adults 51-70 10 mcg (400 IU) 10 mcg (400 IU)
Adults 70+ 15 mcg (600 IU) 15 mcg (600 IU)
Pregnancy all ages - 5 mcg (200 IU)
Breastfeeding all ages - 5 mcg (200 IU)

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What are the signs of vitamin D deficiency?

When the body lacks vitamin D, calcium absorption cannot be increased enough to satisfy its needs. Because of this, PTH production by your parathyroid glands is increased and calcium is transferred from your skeletal bones to participate in this process. This is known as secondary hyperparathyroidism. In addition to a severe risk in the healthiness of your bones, it increases your risk of osteoporosis and an array of other health problems.

Rickets – In both infants and children, a several vitamin D deficiency results in that inability for your body to mineralize bones. Bones that are rapidly growing are most affective by this. Without mineralization, weight-bearing limbs (arms, legs) become bowed. In severe cases, this is accompanied with low serum levels that can cause seizures. (4)

Osteomalacia – Although adult bones no longer continue to grow, they are constantly turning over (remodeling). In vitamin D deficiency with adults, the bone matrix is preserved but bone mineral is lost. This results in bone pain and very weak, soft bones.

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Who can benefit from using vitamin D supplements?

Everybody can benefit from taking vitamin D. Vitamin D helps prevent many common diseases and illnesses that inflict millions every year, including breast cancer, colorectal cancer, prostate cancer, osteoporosis, autoimmune diseases, and high blood pressure. (6)

Benefits to bodybuilders/athletes:

  • Maintains healthy strong bones
  • Helps prevent muscle cramps

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Does vitamin D have any side effects?

No, as long as you don’t take too much. It’s recommended that you do not take more than 50 mcg daily, as prolonged exposure to too much vitamin D can cause bone loss, kidney stones, and calcification of organs such as your heart and kidneys if left untreated. (7)

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