Dietary Supplements: What's Best for Weight Loss, Diabetes, and Thyroid Disease

With Laura Shane-McWhorter, PharmD, CDE, and Scott Isaacs, MD

If you are taking a dietary supplement—or several—you are in very good company. At least a third of Americans take what is known as MVMS, or multivitamin and mineral supplements, ranging from a daily multivitamin to green tea extract, fish oil, vitamin D, garcinia cambogia, and many others. And as you age, you’re more likely to seek out a supplement for whatever ails you.1

If you are trying to lose weight, manage your blood glucose, or improve your thyroid functioning, you may be tempted to turn to supplements to see if you avoid taking medication. Not so fast!

Can dietary supplements fix what ails us?Dietary supplements might seem safe but often offer a false sense of security or much worse.

Reaching for a supplement without knowing exactly what you are taking and before discussing it with your doctor is a big mistake, 2 according to Laura Shane-McWhorter, PharmD, BCPS, BC-ADM, FAADE, a professor emeritus at the University of Utah College of Pharmacy in Salt Lake City, and a certified diabetes educator.

She has done extensive research on supplements—the good, the not-so-good, and the dangerous—and presented her findings at AACE 2018, the 27th American Association of Clinical Endocrinologists Scientific and Clinical Congress in Boston, Massachusetts.2 EndocrineWeb asked her to share the most relevant information for those with diabetes, prediabetes, thyroid issues and weight struggles.

"One of the top 10 reasons for supplement use is weight loss," Dr. Shane-McWhorter says. And about one of three people who begin taking a supplement do so for better weight loss, she says, having been unsuccessful at other lifestyle changes so they turn to supplements, or return to them again hoping to shed unwanted weight.2

A variety of supplements that are promoted for weight control also claim to have benefits for diabetes control and thyroid health, she says.

Dr. Shane-McWhorter offers some guidance on the most popular dietary supplements:2

  • Alpha Lipoic Acid (ALA, or Thioctic Acid)

Promoted to help peripheral neuropathy (the nerve pain that affects many people with diabetes), this supplement has been used for decades in Germany to reduce this type of pain, Dr. Shane-McWhorter says. Its impact on weight loss is under study with some promise of benefit. For example, in one study,3 people taking 1800 milligrams of ALA daily for 20 weeks lost about 4 pounds, while those taking a 1200-mg dose lost about 2.5, and those on placebo lost about 1.8 pounds.

However, the supplement can affect the production of thyroid hormones, so it’s important that your doctor monitor thyroid function levels while you are taking this supplement, she says, especially if you have a thyroid issue. More study is needed to confirm the weight loss benefits, and to see what happens in the longer term.

  • Flaxseed (Linum usitatissimum).

Weight loss is one of the intended uses for flaxseed, along with reducing blood cholesterol, blood pressure, and blood sugar, Dr. Shane-McWhorter told EndocrineWeb. The fiber it contributes makes you feel full so it may help some eat less and lose weight, she says. While some studies have found weight loss or other health benefits, there have been too few people studied to definitively know whether the results are good enough, she says.

If you take flaxseed, be aware of the potential risk for gastrointestinal side effects, she says. As for the daily dose, 10-30 g of soluble fiber taken two hours before a meal is often mentioned, but it’s best to run that by your doctor first make sure this doesn’t interfere with any other medications or health concerns.

  • Garcinia cambogia

For Dr. Oz fans, you’ll recognize this popular weight loss supplement. But Dr. Shane-McWhorter says caution is needed because "there are reports of liver toxicity, and while rare, it may occur in some people."

There is some research to suggest that this supplement may be helpful for weight loss, she says, but the among of loss is slight. In one review,4  the researchers found after evaluating 12 published studies that the supplement did produce weight loss, but only a small amount. For people taking garcinia cambogia for 2 to 12 weeks, those on the nutritional supplement lost about 2 pounds more than those taking a placebo.4  And, some people actually experienced a slight weight gain when taking this supplement,   Dr. Shane-McWhorter says.

Be extra cautious if you are taking an antidepressant as this supplement could interfere with some of these drugs, leading to greater anxiety, she warns, and garcinia cambogia could interact with diabetes medicines, increasing the risk for hypoglycemia.

  • Green tea (Camellia sinensis)

Green tea has true antioxidant properties. It is also being promoted as a weight loss aid. It works, some advocates say, by increasing the amount of fat you burn but there is simply no science behind this claim. While green tea can be sipped as is, it is often combined with caffeine and garcinia cambogia, among other ingredients, to produce weight loss, Dr. Shane-McWhorter says.

In one study,5 researchers compared those who drank green tea with 625 mg catechins and 39 mg of caffeine with those taking the caffeine dose only. The combination group lost an average of nearly 5 pounds; the caffeine-only group a little over two pounds during the 12-week study.5, However, studies results are mixed with some studies showing benefit while others do not. And, she warns, there can be gastrointestinal discomfort, as well as a rise in blood pressure.1

Before Taking Supplements: What Do You Need to Know

Few people mention that they are taking a supplement, or a variety of them, when they see their doctor, Dr. Shane-McWhorter says; yet, it is critical to share this information since nutritional supplements can interact with other medicines, or you could be taking too much, or the supplements  could worsen a chronic condition.

In particular, taking MVM supplements while pregnanct can be hazardous, Dr. Shane-McWhorter points out, due to a variety of factors including ingredients added other than the one you choose to take, and other times there are ingredients added but not listed.

Supplements are treated as foods not drugs by the Food and Drug Administration (FDA), so dietary supplements are not standardized and are not regulated. As such, there is no guarantee that what you’re promised on the label is actually in the pills.

If you are looking for supplement information online, Dr. Shane-McWhorter suggests using these tips, some supplied by the FDA:

  • Who runs the website?
  • Is the purpose to educate or to sell?
  • Are the claims backed up by testimonials only, or by studies in respected medical journals?
  • What date was the information posted or updated?2

The best way to select a nutritional supplement is to look for a “USP Verified” seal-of-approval, which means the manufacturer paid to have a nonprofit third-party lab test and certify that the ingredients in the pills match the labeling on the bottle. You can check to see if the manufacturer of the supplement you want to take has earned the safety seal at USP Quality Supplements or ConsumerLab.

An Endocrinologist Offers an Added Dose of Reality

Caution should be your mantra when considering whether to take a dietary supplement, Scott Isaacs, MD, FACP, FACE, an Atlanta endocrinologist tells EndocrineWeb who attended the presentation at AACE.

"A lot of claims are made for supplements with essentially no scientific evidence to support [them] the vast majority of the time,'' says Dr. Isaacs, in fact, "most of the claims made are simply not true.''

Dr. Isaacs tells his patients: Taking fish oil supplements may help lower serum triglycerides in some people at risk for cardiovascular disease, and many in the US may need to take vitamin D. The only other supplement that has been shown to be even slightly effective is a fiber supplement for weight loss. However, he cautions patients not to expect dramatic results when taking it, and to discuss options to improve your health condition with your doctor to be sure it’s a wise choice for you personally.

He also warns that iodine supplements can ''shut down'' the thyroid. Some alternative medicine doctors might suggest iodine tablets or kelp (high in iodine) help those with a low thyroid function (hypothyroidism),6 according to Mayo Clinic experts. While it is true that an iodine deficiency can lead to low thyroid function, this kind of nutrient deficiency is very rare in the United States and other developed countries, since salt and other foods are fortified with this nutrient to assure we all get enough.  So not only is extra iodine typically not needed, too much can worsen the low thyroid in some people.6

When shopping for dietary supplements, Dr. Isaacs says, keep in mind that the proper role for vitamin and mineral supplements is to address a confirmed nutrient deficiency.  Vitamin D is one such nutrient that is commonly low in many people in the US, particularly those in the northern climates, and for which a single vitamin supplement is warranted if prescribed by your doctor. However, if you do not have a known deficiency, don't expect any significant benefit. More importantly, be aware of potential harm.

Nutrient Supplements to Avoid

Certain dietary supplements should be avoided due to adverse side effects or other harmful interactions, Dr. Shane-McWhorter says.

Here is her list,1 and her explanation as to why to avoid them:

HCG:  This hormone, produced by the human placenta during pregnancy, is marketed along with a very low calorie (500/day) diet for weight loss. HCG is OK'd by the FDA as a prescription drug for certain conditions, such as female infertility, but not for weight loss. It's not approved for sale in over-the-counter products, either.7

Bitter Orange This replaced ephedra when it was taken off the market. One form of bitter orange, with m-synephrine, can cause heart toxicity, Dr. Shane-McWhorter says.

Red Raspberry Ketones: This dietary supplement may be more popular given all the attention to the Keto diet but don't be swayed as this supplement can also lead to heart problems, and is especially dangerous if you take the blood thinner warfarin.

Caffeine: Especially In large doses, caffeine can raise blood pressure and lead to heart problems. Many experts say up to 400 milligrams a day consumed as coffee is generally OK, but your own doctor has the best advice based on your history and conditions.8

Shane-McWhorter reports no financial conflicts. Dr. Isaacs is a consultant for Novo Nordisk and on the speaker's bureaus for Novo Nordisk, Takeda Pharmaceutical Company, and Orexigen Therapeutics, Inc.

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