Chapter 9. Micronutrients for Energy
Vitamin B6 (Pyridoxine)
Role of Vitamin B6 (Pyridoxine)
Vitamin B6 is the coenzyme involved in a wide variety of functions in the body. One major function of vitamin B6 is the nitrogen transfer between amino acids, which plays a role in amino-acid synthesis and catabolism. It also plays a role in glycogen phosphorylase synthesis and is therefore important for the release of glucose from glycogen in the catabolic pathway of glycogenolysis. B6 is also important in gluconeogenesis, several steps of glucose metabolism, the metabolism of some amino acids, and is required by enzymes for the synthesis of multiple neurotransmitters (Figure 9.7 “The function of vitamin B6 in amino acid metabolism”).
Vitamin B6 is also a required coenzyme for hemoglobin synthesis. A deficiency in vitamin B6 can cause anemia, but it is of a different type than that caused by insufficient folate, cobalamin, or iron, although the symptoms are similar. The size of red blood cells is normal or somewhat smaller, but the hemoglobin content is lower. This means each red blood cell has a decreased oxygen-carrying capacity, resulting in muscle weakness, fatigue, and shortness of breath. Other deficiency symptoms of vitamin B6 can cause dermatitis, mouth sores, and confusion.
Vitamin B6 coenzyme is essential for the conversion of the amino acid methionine into cysteine. With low levels of vitamin B6, homocysteine will build up in the blood. High levels of homocysteine increase the risk of heart disease.
Dietary Reference Intakes for Vitamin B6 (Pyridoxine)
The RDAs and ULs for different age groups for vitamin B6 are listed in the table below.
| Age Group | RDA Females and Males mg/day | UL |
| Infants (0–6 months) | 0.1* | Not possible to determine |
| Infants (7–12 months) | 0.3* | Not possible to determine |
| Children (1–3 years) | 0.5 | 30 |
| Children (4–8 years) | 0.6 | 40 |
| Children (9–13 years) | 1 | 60 |
| Adolescents (14–18 years) | 1.2 (females), 1.3 (males) | 80 |
| Adults (19-50 years) | 1.3 | 100 |
| Adults (>50 years) | 1.5 (females), 1.7 (males) | 100 |
| *denotes Adequate Intake | ||
| Data Source: (“Vitamin B6,” 2016)[1] | ||
Dietary Sources of Vitamin B6 (Pyridoxine)
Vitamin B6 can be found in a variety of foods. The richest sources include fish, beef liver, other organ meats, potatoes, and other starchy vegetables and fruits. For the vitamin B6 content of various foods, see the table below.
| Food | Serving | Vitamin B6 (mg) |
| Chickpeas | 1 c. | 1.1 |
| Beef liver | 3 oz. | 0.9 |
| Tuna, fresh | 3 oz. | 0.9 |
| Salmon | 3 oz. | 0.6 |
| Chicken | 3 oz. | 0.5 |
| Potatoes | 1 c. | 0.4 |
| Banana | 1 medium | 0.4 |
| Ground beef patty | 3 oz. | 0.3 |
| White rice, enriched | 1 c. | 0.1 |
| Spinach | ½ c | 0.1 |
| Data Source: (“Vitamin B6,” 2016)[2] and Vitamin B6, National Institute of Health [3] | ||
Consuming Too Little Vitamin B6 (Pyridoxine)
Symptoms of vitamin B6 deficiency include anemia, convulsions, depression, and inflamed/irritated skin patches.
Consuming Too Much Vitamin B6 (Pyridoxine)
Currently, no adverse effects have been associated with a high dietary intake of vitamin B6, but large supplemental doses can cause severe nerve impairment. To prevent this from occurring, the UL for adults is set at 100 mg/day.
- Dietary Supplement Fact Sheet: Vitamin B6. National Institute of Health, Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/. Updates February 11, 2016. Accessed October 22, 2017. ↵
- Dietary Supplement Fact Sheet: Vitamin B6. National Institute of Health, Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/. Updates February 11, 2016. Accessed October 22, 2017. ↵
- https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/ ↵
