Vitamin B-complex supplements include all of the essential B vitamins in one pill. Some contain 100 percent of the recommended daily allowance (RDA) of every B vitamin. Others contain higher doses of some or all of these vitamins.

Many people get all the vitamin B they need from a varied, healthful diet, but others benefit from taking a vitamin B-complex supplement.

What is in the vitamin B complex?

Vitamin B-complex supplements should include all of the essential B vitamins.

If a product contains the vitamin B complex, it should have some of each of the following:

Vitamin B-1 – thiamin

Vitamin B-1 is vital to the healthy growth and function of organs, including the brain and heart.

Vitamin B-2 – riboflavin

The body needs vitamin B-2 to break down fats and drugs.

Vitamin B-3 – niacin

The body needs niacin to maintain healthy skin, nerves, and digestion. Doctors sometimes prescribe high doses of niacin to help improve cholesterol levels.

Vitamin B-5 – pantothenic acid

Vitamin B-5 is essential for the health of the brain and nervous system.

Vitamin B-6 – pyridoxine

Vitamin B-6 helps the body make new red blood cells, which carry oxygen throughout the body. It also helps keep the immune system strong.

Vitamin B-7 – biotin

Biotin is essential for healthy hair, nails, and nerve function.

Vitamin B-9 – folic acid

The body uses folic acid — or folate, its natural form — to make DNA and genetic material. During pregnancy, folic acid may reduce the risk of certain birth defects.

Vitamin B-12 – cobalamin

The body’s nerve and blood cells require vitamin B-12. Adequate levels of B-12 also prevent pernicious anemia, which is a deficiency of this nutrient.

Daily recommendations

Many B-complex supplements contain about 100 percent of the RDA of each of the eight B vitamins.

However, some contain very high levels of certain B vitamins. Before taking a high-dose supplement, talk with a clinician.

The following are RDAs for each of the B vitamins, in milligrams (mg) or micrograms (mcg), according to The National Institutes of Health Office of Dietary Supplements. Older adults may require higher dosages of some B vitamins.

Benefits and uses

Vitamin B-complex supplements may help with certain health problems. If a person has any of the conditions listed below, they may benefit from taking a supplement that contains B vitamins:

Migraine episodes

Some research suggests that certain B vitamins could help prevent migraine with aura, specifically:

• vitamin B-6
• vitamin B-9
• vitamin B-12

The researchers also suggest that vitamin B-2 could help prevent migraine by influencing mitochondrial dysfunction, which occurs at the cellular level.

Authors of a review study from 2017 looked at the effects of vitamin B-2 on migraine. They report that this vitamin is well-tolerated and effective at reducing migraine frequency in adults, though they recommend further research.

Depression and anxiety

Authors of a study from 2018 state that vitamin B-12 levels play an important role in the development and presentation of depression and anxiety. They report that participants with depression or anxiety had lower levels of B-12 than their control counterparts.

A meta-analysis found that B vitamins could help with depression in certain cases. The researchers said that taking some B vitamins regularly for several weeks to years could reduce the risk of depression relapse.

A small-scale study in India also suggested that B-9 and B-12 deficiencies play a role in depression and anxiety.

Skin wounds

B vitamins may help the skin heal.

One study found that, when applied to the skin, these vitamins helped wounds heal more effectively. Another study found that B-12 improved wound healing in mice with diabetes.

Canker sores

Vitamin B-12 may be helpful in treating canker sores, also known as oral ulcers. A double-blind study found that a B-12 ointment relieved pain better than a placebo.

PMS

Some evidence suggests that taking a combined supplement of B-6 and calcium improves symptoms of premenstrual syndrome (PMS).

A systematic review and meta-analysis also found vitamin B-6 to be helpful in controlling physical and psychological PMS symptoms.

Who should take B-complex vitamins?

The following sections look at who may benefit from taking vitamin B-complex supplements.

Pregnant women

Pregnant women may benefit from taking vitamin B-complex supplements.

B vitamins are particularly important during pregnancy, when a woman should take in least 400 mcg of folic acid every day. Ideally, this would also occur in the months before getting pregnant.

In addition, pregnant women should be consuming folate — the natural form of folic acid — from food sources. Getting the recommended amounts of folic acid and folate reduces the risk of birth defects involving the brain and spinal cord, according to the Centers for Disease Control and Prevention (CDC).

Pregnant women also need plenty of vitamin B-12. Studies show that vitamin B-12 deficiency can lead to early pregnancy loss, low birth weight, high blood pressure in the woman, and fetal abnormalities.

Vegetarians and vegans

People who follow a vegetarian diet do not eat meat, including beef, poultry, and fish. People following a vegan diet do not eat any animal products, including meat, eggs, and dairy products.

Vegetarian and vegan diets can increase a person’s risk of B-12 deficiency. The vitamin is present in many animal-based foods, including meat, eggs, and dairy.

People who eat eggs and dairy products may be getting the B-12 that they need from these foods, but those who eat no animal products may need supplements.

People who have had gastric bypass surgery

Individuals who have undergone gastric bypass surgery, also known as bariatric surgery, often need vitamin supplements.

Research indicates that this surgery increases a person’s need for B-12. There is further evidence that many people need a multivitamin that includes B vitamins and other nutrients after this surgery, at least in the short term.

Older adults

People who are 65 or older may benefit from a B-complex supplement.

Research shows that older adults are more susceptible to vitamin B-12 deficiency. Some evidence suggests that having higher levels of B-12 may help slow the aging of the brain, but confirming this finding requires further research.

Low levels of B-12 and folate — a dietary equivalent of folic acid, or vitamin B-9 — may be associated with depression in older people, according to a systematic review and meta-analysis.

In addition, a study involving older Latino adults found that higher B-6 levels were linked to decreased depression symptoms.

People with other health conditions

A person with any of the following health conditions may benefit from a vitamin B-complex supplement:

Side effects and risks

B vitamins are water-soluble. This means that, most of the time, the body excretes extra B vitamins in the urine.

While a standard dosage does not seem to cause harm, excessively high doses of certain B vitamins can be dangerous. Speak with a clinician before taking very high doses of B-complex supplements.

Possible side effects of B-complex vitamins:

• High blood sugar. High doses of nicotinic acid, a synthetic form of vitamin B-3, can raise blood sugar levels. This can interfere with diabetes medications. People with diabetes or high blood sugar should not take high doses of nicotinic acid (measuring 1,000 mg or more).
• Excess nicotinic acid. Too much nicotinic acid can also cause low blood pressure, fatigue, headaches, rashes, and liver damage.
• Excess nicotinamide. High doses of nicotinamide, another form of vitamin B-3, can cause diarrhea and increased bleeding. This can occur in doses of 500 mg per day. Doses higher than 3,000 mg can cause vomiting and liver damage.
• Excess folic acid. Taking more than 1,000 mcg of folic acid a day can mask a type of anemia caused by vitamin B-12 deficiency.

Taking a high-dose B-complex supplement can also turn the urine bright yellow. This effect is temporary and harmless. Once the kidneys get rid of the extra vitamins, the color will return to normal.

Choosing the right vitamin B-complex supplement

A doctor may recommend a certain type of this supplement, depending on a person’s health needs.

Some vitamin and supplement companies use independent quality testing of their products. Those that pass may have a seal of approval from an independent testing organization.

This seal does not guarantee that the product is 100-percent safe or effective for everyone, but it means that the product contains what is listed on the label without contaminants.

Some testing organizations and their certifications include:

• ConsumerLab.com’s approved quality product seal
• NSF International’s dietary supplement certification
• the verified mark of The United States Pharmacopeial Convention, or USP

Interactions

In most cases, vitamin B does not interact negatively with other medications. However, certain medicines can make a vitamin B deficiency more likely.

These are some examples of medications that can result in low levels of specific B vitamins:

• Blood pressure drugs and chemotherapy drugs can lower a person’s B-1 levels.
• Antiseizure medications used for epilepsy can lower B-3, B-6, and B-9 levels.
• Drugs that treat tuberculosis can cause low levels of B-3 and B-6.
• Certain cancer drugs can lower B-9 levels.
• Certain drugs that treat ulcerative colitis can cause low levels of vitamin B-9.
• Certain antibiotics and medicines for ulcers, diabetes, or gastroesophageal reflux disease, or GERD, may lower B-12 levels.

Which foods contain B vitamins?

Avocados are a major source of B vitamins.

Some foods contain several B vitamins, and a person needs a varied diet to consume all eight.

People can get all the B vitamins that they need from omnivorous, vegetarian, or vegan diets.

However, animal products are a major source of B vitamins, so people following restricted diets should take steps to ensure that they are getting enough of each vitamin from different dietary sources.

Some of the best food sources of B vitamins include:

• beef
• pork
• fish
• organ meats
• avocados
• leafy greens
• nuts
• legumes
• grains
• milk
• cheese
• yogurt
• enriched and fortified breads and cereals
• mushrooms

Learn more about vegetarian and vegan sources of vitamin B-12 here.

Summary

Whenever possible, a person should take in B vitamins by eating a variety of healthful foods. However, some people benefit from taking a B-complex supplement.

People can find these supplements in health or drug stores, or they can choose between brands online.

A B-complex supplement is generally safe when a person takes it as directed. However, only take very high doses of B vitamins under a doctor’s guidance.

Although weight-loss diets traditionally suggest avoiding foods with too much fat, there are good and bad types of fat. Nearly all modern dietary guides encourage eating moderate amounts of good fat, both for weight loss and general health. Researchers generally consider CLA a healthful fat.

The main dietary sources of CLA are dairy products and beef. People believe that this particular fatty acid has a range of health benefits. However, while CLA seems to be safe, researchers disagree about its benefits for health.

In this article, we take a close look at the uses, benefits, and risks of CLA in the diet and in supplements.

What is conjugated linoleic acid?

A person can include CLA in their diet or take supplements.

CLAs are a family of fatty acids originating in animal products, including meat and dairy. CLAs contain omega-6 fatty acids. They are polyunsaturated fat, which the American Heart Association (AHA) say can have beneficial effects on the heart.

CLAs are also technically trans fats, which, in most cases, are unhealthful fats. However, CLA is a natural form of trans fat and does not seem to have the same negative health effects as artificially produced, industrial trans fats. The AHA has linked artificial trans fats to a higher risk of heart disease.

While there is a large amount of evidence to show that industrial trans fats are harmful, the research on natural trans fats and their effects is limited and inconclusive.

Possible health benefits

Many people use CLA supplements, believing that they have benefits for weight loss and heart health. The evidence is mixed, however, and many of the studies involve animals instead of humans. Consequently, the research is not yet clear about the exact health benefits of CLA.

The following sections discuss the possible benefits of CLA and what the current research suggests.

Weight loss

According to the Office of Dietary Supplements (ODS), “CLA may help you lose a very small amount of weight and body fat.“

A 2015 review paper states that CLA plays a major role in breaking down fats in the body. This may be why people believe CLA can help with weight loss.

While many studies have shown substantial weight loss in animals, a 2015 review study says that these results do not necessarily apply to humans.

Several studies show that CLA promotes slight weight loss when researchers compare it with placebo groups. However, these examples say that the evidence is inconsistent across the studies.

Bodybuilding

There are no studies looking at the effects of CLA on bodybuilding specifically. A 2015 review of available research suggests that the benefits of taking CLA supplements alongside exercising vary.

The researchers, however, do include several studies that showed CLA supplements could reduce body fat and improve lean body mass, which is the ratio of fat to body weight.

In one study, participants who took 1.8 mg of CLA for 12 weeks and went to the gym for 90 minutes three times per week reduced their body fat but not their body weight when the researchers compared them with a placebo group. The authors said that CLA might reduce fat deposition.

Weight loss but with fewer benefits?

Recent studies have questioned whether CLA-induced weight loss has the same benefits as traditional methods of weight loss, the latter being calorie restriction and exercise.

One 2017 study compared two groups of obese mice with characteristics of human metabolic syndrome. To test weight loss, the researchers gave the first group of animals CLA supplements while putting the second group on a calorie-restriction diet.

The scientists studied the physical changes between the two groups. Both groups lost equal amounts of weight, though they had different physical changes:

• The mice that took CLA supplements lost subcutaneous fat, which is a protective, healthy form of fat, without losing harmful visceral fat.
• The calorie restriction group improved markers of diabetes, such as reduced fasting blood glucose levels, while the CLA group did not. This makes sense as visceral fat is a major contributor to insulin resistance.

The study concluded that calorie restriction was a healthier form of weight loss than taking CLA supplements.

Heart health

Atherosclerosis, or hardening of the arteries, is when plaque builds up in the arteries. This is a risk factor for heart disease.

One 2018 study on obese mice suggested that taking CLA supplements could protect against atherosclerosis.

However, researchers need to do further studies before they know the true effects of CLA on atherosclerosis in humans.

Sources

People can get CLA from their diet by eating foods naturally rich in CLA or by taking CLA supplements.

Meat and dairy

Consuming CLA-rich butter is a way of benefiting from the fatty acid.

Animal products from ruminants, such as cows, goats, sheep, and deer contain CLA. These products include meat, milk, and cheese.

The amount of CLA in animal products depends on farming techniques. Products from grass-fed animals contain more CLA than those from grain-fed animals.

Over recent decades, numerous studies have shown that grass-based diets improve fatty acid ratios, specifically increasing CLA and omega-3 content, and also increase the healthful antioxidant content in beef.

Feeding animals plant sources of linoleic acid, such as sunflower, soybean or linseed oil, can also increase the amount of CLA in their milk fat.

A popular method of consuming CLA-rich butter is bulletproof coffee, which combines coffee, oil, and butter.

CLA supplements

The type of CLA in supplements is different from natural forms from animal products. To make supplements, manufacturers create CLA by chemically altering plant sources of linoleic acid.

Several studies recommend getting CLA from natural sources instead of supplements.

Dosage

There are no established guidelines, but past studies show effects from at least 3 g a day. Studies on fat loss used between 3.4 g and 6.8 g a day.

The ODS say CLA seems to be safe when people take up to 6 g per day for a year. Beyond this, studies so far are inconclusive about how much CLA people may consume.

Dramatic results seen in animal studies required mice to consume large amounts of CLA for effects. Also, there are few studies into long-term CLA supplementation.

Risks and side effects

The ODS report that CLA may cause side effects, such as:

Some studies suggest an association between the dosages people must consume to promote weight loss and negative effects, such as systemic inflammation and insulin resistance. One study also suggests that CLA may worsen fatty liver disease.

As a result of these concerns, more research must be done into the possible side effects of CLA in humans.

Summary

CLA is present in food products from ruminants, including cows, goats, and sheep. Products from grass-fed animals contain more CLA than products from grain-fed animals.

Official sources state that CLA seems to be safe, though people may experience mild side effects, such as digestive issues.

While studies show potential for the use of CLA in losing weight and increasing lean body mass, more comprehensive studies are necessary.