Feeling weak, sluggish, or anemic? You may
not be getting enough B vitamins. These are a group of eight vitamins
that have important metabolic roles in converting food into energy.
They’re also necessary for a wide range of other processes, such as
blood cell production, neurological function, cellular signaling, DNA
production and repair, metabolizing amino acids, and more. B vitamins
are also believed to help reduce stress, anxiety, memory loss, and heart
disease risk.
Importantly, we have to replenish our B
vitamins regularly. Because they’re water soluble, B vitamins aren’t
stored in the body, and the ones that aren’t used get flushed out.
That’s why we need to obtain B vitamins daily to avoid deficiencies.
B vitamin deficiencies, although uncommon, can be dangerous. There
are eight great B vitamins, but let’s look at the four in which
deficiencies may be more common and can be more serious.
Vitamin B1 (thiamine) deficiency
Most people in the United States get enough thiamine (vitamin B1).
But for those who develop a thiamine deficiency, it can become a
serious, potentially life-threating problem. Notably, people with
chronic alcoholism frequently develop thiamine deficiency because
ethanol reduces gastrointestinal absorption of thiamine, thiamine stores
in the liver, and thiamine phosphorylation.
Other groups prone to thiamine deficiency include older adults,
people with HIV/AIDS, people with diabetes, and those who have undergone
bariatric surgery.
In its early stage, signs and symptoms of thiamine deficiency are
nonspecific, and may include fatigue, irritability, poor memory, sleep
disturbances, precordial pain, anorexia, and abdominal discomfort.
In severe stages, thiamine deficiency results in beriberi, which is
characterized by peripheral neuropathy and muscle wasting, as well as
impaired sensory, motor, and reflex functions. In rare cases, people
with beriberi develop congestive heart failure that leads to edema in
the legs and sometimes death. Although beriberi is rare in the United
States, it does still occur here.
A more familiar consequence of thiamine deficiency in the United
States is Wernicke-Korsakoff syndrome, which most commonly develops in
people with chronic alcoholism—about 8-10 times more commonly than in
the general population. Wernicke-Korsakoff syndrome often manifests in
two phases. The first is Wernicke’s encephalopathy, an acute,
life-threatening phase that’s characterized by peripheral neuropathy.
Without supplemental thiamine treatment, up to 20% of people with
Wernicke’s encephalopathy die.
Those who survive develop the second phase, Korsakoff’s psychosis,
which is associated with severe short-term memory loss, disorientation,
and confusion between real and imagined memories. Even with parenteral
thiamine treatment, about one-quarter of patients with Korsakoff’s
psychosis do not completely recover.
The daily Recommended Dietary Allowance (RDA) for thiamine is 1.2 mg
in adult men and 1.1 mg in adult women. Primary food sources include
whole grains, meat (notably pork), and fish. Americans get most of their
thiamine from cereals and breads.
Vitamin B6 deficiency
Vitamin B6 deficiency is relatively rare in the United States, but
some individuals can have low vitamin B6 status. Groups most likely to
have inadequate vitamin B6 intake include people with poor renal
function, including those with end-stage renal disease and chronic renal
insufficiency, and people with autoimmune disorders, including
rheumatoid arthritis. Other groups include patients with celiac disease,
Crohn’s disease, ulcerative colitis, inflammatory bowel disease, and
other malabsorptive autoimmune disorders, as well as people with alcohol
dependence.
In addition, 24% of people in the United States who don’t take
supplements containing vitamin B6 have low plasma concentrations of the
vitamin. In particular, teenagers have the lowest vitamin B6 levels,
followed by adults aged 21-44 years. Interestingly, the elderly do not
have significantly low vitamin B6 plasma levels, even those who didn’t
take supplements.
People with borderline vitamin B6 levels or mild deficiency may show
no signs or symptoms for months or even years. In individuals with true
vitamin B6 deficiency, symptoms can include anemia, seborrheic
dermatitis, peripheral neuropathy, cheilosis (scaling on the lips and
cracks at the corners of the mouth), glossitis (swollen/painful tongue),
weakened immune function and, in adults specifically, depression,
confusion, electroencephalographic abnormalities, and seizures. In
infants, vitamin B6 deficiency causes irritability, abnormally acute
hearing, and convulsive seizures.
People with low vitamin B6 concentrations should be sure to get
adequate nutrients from food sources or vitamin supplements. Individuals
with alcohol dependence or malabsorptive disorders may benefit from
pyridoxine supplementation. Importantly, the patient’s underlying
condition also needs to be addressed.
The daily RDA for vitamin B6 is 1.3 mg in adults up to age 50, and is
higher in pregnant (1.9 mg) and lactating women (2.0 mg). In adults age
51 and older, the daily RDA is 1.7 mg for men and 1.5 mg for women.
Dietary sources of vitamin B6 include a wide variety of foods,
particularly fish, beef liver and other organ meats, potatoes and other
starchy vegetables, chickpeas, and non-citrus fruits.
Vitamin B9 (folate) deficiency
Although most Americans get enough vitamin B9 (folate), certain
populations—including women of childbearing age and non-Hispanic black
women—may not get a sufficient amount. Even among girls and women who
take supplements with folic acid, 19% of those aged 14 to 18 years and
17% of those aged 19 to 30 years have an inadequate intake of folate.
Likewise, 23% of non-Hispanic black women don’t get enough folate
compared with 13% of non-Hispanic white women.
Other groups may also not get enough folate. For instance, pregnant
women have a higher demand for folate, so they’re recommended to take a
prenatal vitamin supplement that includes folic acid. Indeed, pregnant
women with insufficient folate have an increased risk of giving birth to
infants with neural tube defects. Inadequate folate intake in mothers
is also associated with low infant birth weight, preterm delivery, and
fetal growth retardation. The good news: Since 1998, the FDA has
required manufacturers to add 140 mcg of folic acid to every 100 g of
enriched breads, cereals, flour, cornmeal, pasta, rice, and other grain
products to reduce the risk of these defects.
In addition, people with alcohol use disorder often have poor diets
that don’t provide enough folate. Alcohol also interferes with folate
absorption and hepatic uptake. Others who may not get enough folate
include people with malabsorptive disorders and those with
MTHFR gene polymorphism.
Although these groups may be at risk of insufficient folate intake,
isolated folate deficiency is uncommon—it usually occurs along with
other nutrient deficiencies related to poor diet, alcoholism, and
malabsorptive disorders.
The primary clinical sign of folate deficiency (as well as vitamin
B12 deficiency) is megaloblastic anemia, which is characterized by
large, abnormally nucleated red blood cells. Symptoms include weakness,
fatigue, difficulty concentrating, irritability, headache, heart
palpitations, and shortness of breath.
Other signs and symptoms of folate deficiency are soreness and
ulcerations on the tongue and oral mucosa; pigmentary changes in skin,
hair, or fingernails; gastrointestinal symptoms; and elevated blood
concentrations of homocysteine.
The RDA for folate in adults is 400 mcg dietary folate equivalents
(DFE) per day, and is higher in pregnant and (600 mcg DFE) and lactating
women (500 mcg DFE). Folate is naturally present in a wide variety of
foods and found in the largest amounts in vegetables (especially
spinach, asparagus, and brussels sprouts), meat (particularly beef
liver), fruits and fruit juices, nuts, beans, peas, seafood, eggs, dairy
products, poultry, and grains (notably breakfast cereal).
Bear in mind that some people are at risk of getting
too much
folic acid. About 5% of adults aged 51-70 years, as well as men aged 71
years and older, have folic acid intakes that exceed the tolerable
limit of 1,000 mcg per day, mostly due to the folic acid they get from
dietary supplements.
Vitamin B12 deficiency
Some people—particularly older adults and people with pernicious
anemia—have difficulty absorbing vitamin B12. Consequently, vitamin B12
deficiency is common in the United States, affecting between 1.5% and
15% of the general population.
Older adults are prone to develop vitamin B12 deficiency due to
atrophic gastritis, a condition that occurs in 10% to 30% of this
population. Atrophic gastritis decreases the secretion of hydrochloric
acid in the stomach, which reduces absorption of vitamin B12.
Similarly, some adults develop pernicious anemia, which is
characterized by a lack of intrinsic factor in the stomach. Without
enough intrinsic factor, people with pernicious anemia don’t properly
absorb vitamin B12.
Other groups at risk of vitamin B12 deficiency include people with
stomach and small intestine disorders (such as celiac disease and
Crohn’s disease), people who have had gastrointestinal surgery (eg, for
weight loss), and strict vegetarians (because animals are the only
natural food source of B12).
Signs and symptoms of vitamin B12 deficiency include megaloblastic
anemia, peripheral neuropathy, fatigue, weakness, constipation, loss of
appetite, and weight loss. Other symptoms include difficulty maintaining
balance, confusion, dementia and, rarely, soreness of the mouth or
tongue.
The daily RDA for vitamin B12 in adults is 2.4 mcg, with higher
amounts recommended for pregnant (2.6 mcg) and lactating (2.8 mcg)
women. Vitamin B12 is naturally found in foods derived from animals,
including seafood (eg, clams, trout, salmon, tuna), meat (notably beef
liver), poultry, eggs, milk, milk products, and (for vegans) fortified
breakfast cereals.
People with atrophic gastritis can absorb the synthetic vitamin B12
added to fortified foods and dietary supplements. So, adults older than
age 50 are recommended to obtain vitamin B12 from vitamin supplements or
fortified foods. People with pernicious anemia are usually treated with
intramuscular injections of vitamin B12.
Other people who have trouble absorbing vitamin B12 from foods—as
well as strict vegetarians who don’t eat foods derived from animal
sources—can get their vitamin B12 from fortified foods, vitamin
supplements, or vitamin B12 injections.
Need more vitamin B? Foods like
liver, tuna, leafy greens, eggs, nuts, beans, and cereals help to make
up for any diet deficiencies of the B complex vitamins.