Some nutrition myths have been handed down through generations, while others have been introduced more recently by self-proclaimed health experts. Ultimately, they often make their way into the doctor’s office, where patients want a clear, concise answer. Which of these 10 widely circulated claims actually holds up under scientific scrutiny?

Fact-Checking 10 Myths

1. Margarine is healthier than butter.

This is true in terms of fatty acid composition. Margarine, especially that made from canola oil, contains more unsaturated fatty acids and therefore has a better fatty acid composition. This is because unsaturated fatty acids have a positive effect on the cardiovascular risk profile because they can help lower cholesterol levels and reduce inflammation in the body. Butter is high in saturated fatty acids. But butter is a natural and minimally processed product. Both butter and margarine contain about 80% fat and provide approximately 750 kcal/100 g, which is why they should generally be used sparingly.

2. If you want to avoid weight gain, you should not eat anything after 6 PM.

Human metabolism does follow a daily rhythm, but the blanket claim that “eating in the evening makes you fat” is not supported. Although newer studies have added to the discussion, the overall evidence remains inconclusive. What continues to matter most is energy balance: Weight gain or loss depends largely on how much and what types of food people eat over the course of the day, as well as how much they exercise. In general, consuming more calories than you burn leads to weight gain. That said, a late dinner can still interfere with sleep for some people.

3. Red meat and processed meats should be avoided as much as possible.

Red meat — that is, meat from beef, pork, lamb, or sheep and goat — is richer in nutrients such as iron, vitamin B₁₂, and zinc than white meat. However, a high intake of red meat, and especially processed sausage, increases the risk for cardiovascular disease and colorectal cancer. As for white meat — that is, meat from poultry such as chicken — there is, according to current scientific knowledge, no link to cancer. A varied selection of both red and white meat ensures an adequate nutrient intake while minimizing the risk for disease. In general, the German Nutrition Society recommends eating no more than 300 g of meat and sausage per week. Even if less or no meat is consumed per week, nutritional goals can still be met.

4. Animal protein is better than plant-based protein.

Plant-based and animal proteins differ in the composition and bioavailability of their amino acids. Protein from animal-based foods generally contains all essential amino acids in sufficient quantities. Plant-based foods do not provide the full range of these amino acids. However, this can be balanced through a strategic combination of foods, such as pairing legumes with grains, as in lentil dishes with rice or pea stew with bread.

5. Honey, agave syrup, or whole-cane sugar are healthier than table sugar.

That is not true. “Alternative” sweeteners such as whole-cane sugar, honey, agave syrup, or other concentrated syrups offer no health benefits compared with “regular” table sugar. A high and regular intake of sugar is associated with an increased risk of being overweight or obese, type 2 diabetes, cardiovascular disease, and tooth decay. This holds true regardless of the type of sugar used. The amount is more important than the type of sugar.

6. A shot of liquor after a meal aids digestion.

No, alcohol does not stimulate digestion. The “digestif” is a myth: It actually delays gastric emptying. Nevertheless, for some people, alcohol creates the short-term impression of a relaxed feeling after a hearty meal because it dilates the blood vessels and relaxes the muscle cells. It’s better to drink a cup of tea or coffee after a sumptuous meal. Ideal choices include, for example, sage, fennel, or peppermint tea because the essential oils in these herbs promote digestion. A walk in the fresh air further stimulates circulation and digestion.

7. A vegan diet without dietary supplements leads to deficiency symptoms.

A well-planned vegan diet often has a more favorable composition in terms of fiber, fruits, and vegetables than the mixed diet commonly consumed in Germany. Nevertheless, an adequate supply of certain micronutrients is not guaranteed. Therefore, the diet must be supplemented with dietary supplements or fortified foods. Vitamin B₁₂ and iodine are particularly critical nutrients. Vitamin B₁₂ is found in sufficient quantities only in animal-based foods. Therefore, an adequate supply of vitamin B₁₂ in a vegan diet is possible only through the use of nutritional supplements.

Iodine is considered a critical nutrient in the general German population, regardless of diet. Iodine intake on a vegan diet appears to be even more inadequate because important sources such as dairy products and fish are excluded. Fluoridated iodized salt and iodine-fortified foods, such as plant-based beverages, contribute to iodine intake. Seaweed with a defined iodine content can also support iodine intake. If insufficient iodine-rich foods are consumed, an iodine supplement should be taken in consultation with a doctor.

In addition, protein and essential amino acids, along with long-chain n-3 fatty acids such as eicosapentaenoic acid and docosahexaenoic acid — particularly in pregnant and breastfeeding women, as well as children and adolescents — are among the nutrients of concern. Other potentially critical nutrients include riboflavin, vitamin D, and minerals such as calcium, iron, zinc, and selenium. Vitamin A may also be a nutrient of concern in a vegan diet.

8. Taking vitamin C protects against colds.

There is no scientific evidence that the prophylactic intake of vitamin C in high doses (≥ 200 mg/d) can prevent or cure colds. It might be justified only for individuals under severe physical stress or in cold environments because studies have observed a lower risk for infection with supplementation in these cases. A healthy person needs an average of about 100 mg of vitamin C per day. In this country, a clinically relevant vitamin C deficiency is practically nonexistent.

9. People with lactose intolerance must avoid milk and all dairy products.

Most patients with lactose intolerance can tolerate small amounts of lactose, although the amount varies from person to person depending on several factors and should be assessed individually. Complete avoidance is usually unnecessary. Many dairy products are naturally low in lactose and are generally well tolerated. Aged cheeses such as Emmental, Gouda, Edam, and Parmesan are often acceptable, as are fermented dairy products such as yogurt, kefir, and quark, because the lactic acid bacteria they contain have already broken down much of the lactose. In general, it helps to consume milk and dairy products in small amounts throughout the day and with meals. Maintaining adequate calcium intake is also important and can be achieved through calcium-rich vegetables such as broccoli, kale, and fennel, as well as nuts, calcium-rich mineral water, or fortified plant-based beverages.

10. Healthy people do not need dietary supplements.

A healthy adult who eats a balanced diet is generally adequately supplied with essential macro- and micronutrients and does not need dietary supplements. Only in certain life situations — such as during pregnancy or while breastfeeding — and for specific nutrients is the risk for inadequate intake increased, even in healthy individuals. In such cases, targeted supplementation may be indicated. Supplementation should only be undertaken after consulting a doctor and undergoing appropriate laboratory testing.

Your Real-World Experience

We’ve listed 10 common myths here, but the list could likely go on forever. With countless dietary guides and fleeting social media trends, new claims emerge almost daily that can become firmly entrenched in patients’ minds. What nutrition myths have you encountered recently in your practice? Feel free to write in the comments which unsubstantiated claims you regularly hear — and how you deal with them.

This story was translated from Coliquio, part of the Medscape Professional Network.