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Did you know DNA influences your risk of vitamin B6 deficiency?

Vitamin B6, morning sickness and genetics

Morning sickness, you were sure it would only last a few weeks. Here you are far into your second trimester, still constantly feeling nauseous. None of the natural remedies have helped and you’ve already refused Diclectin. Then your doctor suggests vitamin B6. A plain, old vitamin found in beef, bananas and chickpeas and amazingly, it does the trick. There are many theories as to why this vitamin relieves morning sickness and one of them happens to be genetics. A gene, NBPF3, which can affect vitamin B6 levels, is probably the best way to start testing the link between morning sickness and vitamin B6.

Vitamin B6, sometimes known as pyridoxene, actually refers to a group of interchangeable chemicals. The active form, pyridoxal 5-phosphate (PLP), is involved in more than 100 chemical reactions and controls the turnover of pretty much every major source of energy in the body, from proteins to sugars and fats. PLP also has a hand in making haemoglobin (an iron-containing protein found in red blood cells), producing neurotransmitters (chemical messengers in the brain) and in building nucleotides (the building blocks of DNA). The involvement of vitamin B6 in pregnancy is most likely linked to hormone function because PLP also influences the activity of steroid receptors that relay signals from two major pregnancy-related hormones – estrogen and progesterone.

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The role of NBPF3 was uncovered in a study searching for genetic variants (small changes in the DNA that exist between people) to explain differences in serum vitamin B levels. Researchers identified the rs4654748 C variant near the NBPF3 gene, which is associated with lower vitamin B6 levels. Not much is known about the function of the neuroblastoma breakpoint family member 3 protein encoded by the NBPF3 gene, therefore it is hard to determine the exact mechanism behind the link to vitamin B6.

Vitamin B6 is an essential nutrient, which means it has to be acquired as part of our diet because we are unable to synthesize it ourselves. Fortified cereal, russet potatoes and salmon are great sources of this vitamin. More details on vitamin B6-rich food sources can be found at the end of the article, along with the recommended daily allowance for vitamin B6. Severe vitamin B6 deficiency is quite rare, but children and elderly are more likely to be mildly deficient. Symptoms associated with severe deficiency include muscle weakness, irritability, nervousness, depression, difficulty concentrating, short-term memory loss, inflammation of the tongue, sores or ulcers of the mouth and ulcers of the skin at the corners of the mouth. While vitamin B6 supplements are readily available, they should be taken with caution. Very high doses of this vitamin are also dangerous and can cause nerve damage, with symptoms including pain and numbness of arms and legs, and difficulty walking. Side effects of moderate toxicity involve skin allergies, light sensitivity, headaches, nausea, abdominal pain and loss of appetite. A table showing the tolerable upper limits of vitamin B6 is at the end of this article. Talking to your healthcare practitioner before taking vitamin supplements is your safest option.

Aside from battling morning sickness, vitamin B6 is implicated in protecting us from immune dysfunction, cardiovascular disease, inflammation, Alzheimer’s, depression, kidney stones and even cancer. In one study, women taking the highest levels of vitamin B6, either as part of their diet or as a supplement, had a 34% lower risk for coronary artery disease compared to women with the lowest intake. Another recent study suggests that this vitamin can treat symptoms of schizophrenia. Overall, vitamin B6 is quite a versatile nutrient that offers a protective role against multiple diseases and may be used as a treatment option for several others.

When it comes to the connection between genetics, vitamin B6 and morning sickness, we currently have two separate pieces of the puzzle: (1) vitamin B6 levels are affected by variations in the NBPF3 gene, (2) vitamin B6 supplements offer effective relief from morning sickness. One possible explanation is that women with lower vitamin B6 levels experience more severe morning sickness and will benefit more from supplements than women with normal levels. If this is true, then women with the NBPF3 variant will also have an increased risk of morning sickness during pregnancy. While these are just theories, and future studies are needed to conclusively link NBPF3 to morning sickness, it is exciting to speculate how revolutionary changes in DNA sequencing technologies will soon allow us to remedy conditions due to nutritional imbalances that have caused suffering to so many people in the past.

Recommended dietary allowances for vitamin B6.

Recommended dietary allowances are shown in milligrams (mg). For infants from birth to 12 months, an adequate intake is shown, which is equivalent to the mean intake of vitamin B6 in healthy, breastfed infants.

Age Male Female Pregnancy Lactation
0–6 months 0.1 mg 0.1 mg
7–12 months 0.3 mg 0.3 mg
1–3 years 0.5 mg 0.5 mg
4–8 years 0.6 mg 0.6 mg
9–13 years 1.0 mg 1.0 mg
14–18 years 1.3 mg 1.2 mg 1.9 mg 2.0 mg
19–50 years 1.3 mg 1.3 mg 1.9 mg 2.0 mg
51+ years 1.7 mg 1.5 mg

Selected foods sources of vitamin B6.

The Daily Value (DV) for vitamin B6 is 2 mg for adults and children age 4 and older. This DV was developed by the U.S. Food and Drug Administration (FDA) to help consumers compare the nutrient contents of products within the context of a total diet.

Food mg per serving Percent DV
Chickpeas, canned, 1 cup 1.1 55
Beef liver, pan fried, 3 ounces 0.9 45
Tuna, yellowfin, fresh, cooked, 3 ounces 0.9 45
Salmon, sockeye, cooked, 3 ounces 0.6 30
Chicken breast, roasted, 3 ounces 0.5 25
Breakfast cereals, fortified with 25% of the DV for vitamin B6 0.5 25
Potatoes, boiled, 1 cup 0.4 20
Turkey, meat only, roasted, 3 ounces 0.4 20
Banana, 1 medium 0.4 20
Marinara (spaghetti) sauce, ready to serve, 1 cup 0.4 20
Ground beef, patty, 85% lean, broiled, 3 ounces 0.3 15
Waffles, plain, ready to heat, toasted, 1 waffle 0.3 15
Bulgur, cooked, 1 cup 0.2 10
Cottage cheese, 1% low-fat, 1 cup 0.2 10
Squash, winter, baked, ½ cup 0.2 10
Rice, white, long-grain, enriched, cooked, 1 cup 0.1 5
Nuts, mixed, dry-roasted, 1 ounce 0.1 5
Raisins, seedless, ½ cup 0.1 5
Onions, chopped, ½ cup 0.1 5
Spinach, frozen, chopped, boiled, ½ cup 0.1 5
Tofu, raw, firm, prepared with calcium sulfate, ½ cup 0.1 5
Watermelon, raw, 1 cup 0.1 5

Tolerable upper intake levels for vitamin B6.

These upper limits apply to both food and supplement intakes, but do not apply to individuals receiving vitamin B6 for medical treatment under the care of a physician. For infants from birth to 12 months, breast milk, formula and food should be the only sources of vitamin B6.

Age Male Female
0–12 months Not possible to establish Not possible to establish
1–3 years 30 mg 30 mg
4–8 years 40 mg 40 mg
9–13 years 60 mg 60 mg
14–18 years 80 mg 80 mg
19+ years 100 mg 100 mg

Recommended dietary allowances, food sources and tolerable upper limits are obtained from the Vitamin B6 Dietary Supplement Fact Sheet (National Institutes of Health).

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