Keto Long-Term Risks: Jama Study Findings Explained

The ketogenic, or keto, diet has become increasingly popular, with 23 million Americans choosing to follow it in 2022. The diet is characterised by a high intake of fat, moderate protein, and low carbohydrate consumption. While it has been used to help reduce the frequency of epileptic seizures, particularly in children, it has also been adopted by many for weight loss. However, the question of whether keto is dangerous in the long term has been the subject of much debate. A 2020 article in the medical journal JAMA suggests that the diet may be risky in the long term, potentially leading to increased mortality and making it difficult to obtain optimum amounts of antioxidant phytonutrients from fruits and vegetables. Other health experts have also warned of the potential dangers of keto, including vitamin and mineral deficiencies, adverse effects on athletic performance, weight regain, blood vessel damage, and an increased risk of chronic diseases such as heart disease, cancer, and Alzheimer's Disease.

Keto may cause vitamin or mineral deficiencies

The keto diet is a high-fat, moderate protein, and low-carbohydrate diet that has become increasingly popular in recent years. While the diet has been praised for its weight loss benefits, there are concerns that following a keto diet long-term may lead to vitamin or mineral deficiencies. This is because many vitamin- and mineral-rich foods, such as fruits, vegetables, grains, and legumes, are restricted on a keto diet.

Micronutrient Deficiencies

Vitamins and minerals, also known as micronutrients, play crucial roles in the body's daily functions. A well-balanced diet that includes whole foods should provide adequate amounts of most micronutrients. However, on a keto diet, the intake of certain micronutrients may be insufficient.

One study found that a 3-day ketogenic diet that selected nutrient-dense foods was analysed for micronutrient content. Out of the 24 micronutrients evaluated, 19 were below the Dietary Reference Intakes (DRI) standards, with 11 provided at less than 50% of the DRI. These included Thiamin (B1), Folate (B9), Pantothenic Acid (B5), Calcium, Copper, Iron, Magnesium, Manganese, Molybdenum, Selenium, and Zinc.

Another study suggested that individuals following a long-term keto diet may also be deficient in vitamins Biotin (B7), Vitamin D, and Vitamin E, as well as minerals Chromium, Iodine, Potassium, and Sodium.

Specific Vitamin and Mineral Deficiencies

Calcium

People on long-term keto diets often lose too much calcium in their urine, which can lead to lower bone density. Additionally, dietary calcium intake may be lower on a keto diet due to the restriction of calcium-rich foods such as fruits, vegetables, dairy, and grains.

Magnesium

Magnesium is another mineral that has been observed to decrease on a long-term keto diet. This mineral is important for energy production and proper nerve and brain function. Symptoms of magnesium deficiency include muscle cramps, headaches, anxiety, nervousness, and constipation.

Iron

Even though keto diets usually involve eating ample quantities of meat, they can also lead to reduced iron levels. Iron is necessary for energy production and red blood cell formation, and deficiency can cause fatigue and breathing difficulties during exercise.

Selenium

Selenium is a mineral that plays a role in heart health, reproduction, thyroid hormone production, and protection against oxidative stress. Research has found that keto diets can lead to lower selenium levels and cause deficiencies in the long run.

Carnitine

Carnitine is a compound found in high quantities in the heart and muscles, and it helps transport fatty acids to the mitochondria for energy production. While the body can produce carnitine, 75% of our daily requirements come from our diet, mainly from meat and dairy. On a keto diet, carnitine is used up more quickly, and deficiency may develop on long-term diets.

Strategies to Prevent Deficiencies

To prevent vitamin and mineral deficiencies while on a keto diet, it is important to include a variety of nutrient-dense foods, such as grass-fed meat, poultry, wild-caught fish, liver, spinach, kale, nuts, and seeds. Additionally, supplementation with certain vitamins and minerals may be necessary to correct deficiencies.

It may damage blood vessels

The keto diet may damage blood vessels, according to researchers from the University of British Columbia. In a 2019 study, they found that indulging in a high-sugar treat while on a high-fat, low-carb diet can damage blood vessels. Senior author Jonathan Little, an associate professor in the School of Health and Exercise Sciences, expressed concern that people on the keto diet may be "undoing some of the positive impacts on their blood vessels if they suddenly blast them with glucose." He further emphasized that their data suggests avoiding cheat days on the keto diet, stating that "a ketogenic diet is not something you do for six days a week and take Saturday off."

The findings of the University of British Columbia study align with the concerns of health experts about the long-term effects of the keto diet on the heart and arteries. A 2019 study published in the Journal of the American College of Cardiology found that people on low-carb diets are more likely to develop atrial fibrillation (AFib) compared to those who consume moderate amounts of carbohydrates. Atrial fibrillation is a type of arrhythmia that increases the risk of blood clots, stroke, and heart failure, according to the American Heart Association (AHA).

Furthermore, a 2018 study published in Lancet linked low-carb diets high in meat and dairy consumption to a higher risk of early death compared to moderate carbohydrate intake or plant-based protein sources. This suggests that the specific foods chosen on a keto diet may play a crucial role in overall health outcomes.

While the keto diet has been associated with weight loss and management of certain health conditions, the potential damage to blood vessels and the increased risk of cardiovascular issues cannot be overlooked. More research is needed to fully understand the long-term effects of the keto diet on the body, particularly regarding vascular health. In the meantime, it is essential to approach the keto diet with caution and seek guidance from medical professionals before starting any restrictive dietary regimen.

It could lead to liver problems

The keto diet could lead to liver problems, specifically non-alcoholic fatty liver disease (NAFLD). NAFLD is a "silent killer" that affects around a quarter of the global population and can lead to cirrhosis and liver cancer. As there is no effective drug therapy for the disease, the only prevention and treatment options are diet and lifestyle modifications.

A ketogenic diet can induce elevated cholesterol and elevated liver enzymes, which are risk factors for NAFLD. In one case, a 57-year-old woman with obesity and a history of binge-eating disorder, post-traumatic stress disorder, and untreated depression and anxiety presented for weight management with laboratory values revealing acutely-worsened hyperlipidemia and elevated liver enzymes. An abdominal ultrasound showed a mildly heterogenous and echogenic liver, without focal lesions, suggestive of NAFLD. The only significant change from a previous consultation four months prior was the introduction of a ketogenic diet.

However, it is important to note that there is also research showing that a ketogenic diet can be an effective treatment for NAFLD. In a study of ten overweight/obese subjects, a 6-day ketogenic diet decreased liver fat content and hepatic insulin resistance. These changes were associated with increased net hydrolysis of liver triglycerides and decreased endogenous glucose production and serum insulin concentrations.

Overall, while there is some evidence that a ketogenic diet may lead to liver problems such as NAFLD, more research is needed to fully understand the potential risks and benefits of this dietary approach.

It may cause constipation

The keto diet is a very high-fat, very low-carb, moderate-protein eating pattern. This way of eating induces a phenomenon called ketosis, where the body burns fat instead of glucose for energy.

The keto diet is typically low in fiber, but individuals following the diet may consume more dairy and drink less water. The combination of these factors can lead to constipation.

Constipation means having fewer than three bowel movements per week. Being constipated may also make your stools hard and lumpy and difficult to pass.

The keto diet restricts all types of carbohydrates, including those present in high-fiber fruits, vegetables, and grains. The digestive system cannot break down fiber, so it stays in the gastrointestinal (GI) tract and adds bulk to stools by drawing water into the intestines. This added bulk and water help keep stools soft and bowel movements regular. Without fiber, constipation is more likely.

Transitioning too quickly to a keto diet can also cause constipation. Drastic changes to a person's diet can negatively affect their digestive system and even cause symptoms such as nausea or constipation. The body needs time to adjust to a new diet, and gradually transitioning to a low-carbohydrate diet over a few weeks may help prevent undesirable digestive side effects.

If you are new to the keto diet, you may find that your constipation lasts only a few days to a few weeks. As your body adjusts to digesting more fats and fewer carbs, your constipation may improve.

• Add more dietary fiber. Fiber-rich keto-friendly foods include non-starchy vegetables, limited amounts of berries, avocados, and nuts.
• Drink plenty of water.
• Exercise regularly.
• Retrain your bowel by drinking sufficient fluids and establishing a regular time for a toilet break.
• Cut back on dairy.

It may affect athletic performance

The keto diet has been a topic of interest for athletes, with some adopting it to boost performance. However, there is conflicting evidence on its effectiveness, and some researchers warn that it may even be detrimental to athletic performance.

The Theory Behind Keto for Athletes

In theory, a keto diet could benefit athletes in two ways: improved body composition and enhanced performance over longer distances. By increasing fat burning, athletes could lower body fat levels and improve their power-to-weight ratio. Additionally, with greater reliance on fat burning, athletes could reduce their dependence on limited muscle glycogen stores, potentially improving performance in very long-distance events.

Research Findings on Athletic Performance

Research findings on the impact of keto diets on athletic performance are mixed. Some studies suggest that keto diets can preserve endurance capacity at moderate intensities, but performance at higher intensities may be compromised. For example, a study on well-trained cyclists found that while submaximal cycling ability was maintained, performance at higher intensities was negatively affected.

A 2019 study published in the Journal of Sports Medicine and Physical Fitness provides further evidence of potential negative effects. In this study, participants performed worse on high-intensity cycling and running tasks after four days on a ketogenic diet compared to those on a high-carb diet. The researchers attributed this to the body being in a more acidic state when in ketosis, which may limit its ability to perform at peak levels.

However, it is important to note that some studies have found no decrement in strength and power performance following a keto diet. For example, a study on elite male artistic gymnasts found no decrement in strength endurance and power after three to four weeks on a keto diet.

Practical Recommendations for Athletes

Based on the current evidence, here are some practical recommendations for athletes considering a keto diet:

• The keto diet may be beneficial during periods of low-intensity, base training, but it is not recommended for high-intensity training periods as it may compromise performance.
• If you are thinking of trying a keto diet, allow at least five days for your body to adapt and benefit from enhanced fat burning.
• For race events of less than three hours, continuing a keto diet is not advised as it may harm maximal performance. Instead, switch to a high-carb diet 24-36 hours beforehand and consume carbohydrates during the race.
• Be aware that individual responses to a keto diet can vary significantly. Some people may experience side effects like poor energy, mental function, sleep issues, and nausea, which could make the diet untenable.

While keto diets may offer some benefits for athletes, particularly in terms of fat burning and body composition, the current evidence suggests that it may negatively impact high-intensity performance. Therefore, athletes should carefully consider the potential risks and benefits before adopting a keto diet and ensure they are well-informed about the latest research findings.

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