Is Vegetarianism the Healthiest Diet? 

1. Nutritional Deficiency: 72-year-old Mr. Wu, who adheres to a vegetarian diet, was shocked to discover that he had severe malnutrition due to a deficiency in vitamin B12, leading to weakness in his limbs and nerve damage. Although vegetarianism can reduce the risk of high cholesterol and cardiovascular diseases, it can also lead to protein deficiency, anemia, and other health problems.

2. The Benefits of Meat for Seniors: Research involving 11 countries revealed that elderly individuals who consume more protein, mainly from meat and eggs, have a lower risk of cancer and a longer lifespan. Meat is a crucial source of nutrients such as B12, calcium, and iron, which are often lacking in elderly individuals.

Additionally, meat consumption can prevent osteoporosis and muscle atrophy. 

3. Choosing the Right Meats: For seniors, it is recommended to consume poultry and fish, as they are low in fat and provide essential amino acids and omega-3 fatty acids. Red meats, such as beef and pork, should be consumed in moderation to prevent an increased risk of cancer and cardiovascular diseases.

It is advised for individuals with high blood pressure, cholesterol, and diabetes to opt for lean cuts of meat and use cooking methods like stewing to reduce saturated fat. 

In conclusion, a balanced diet that includes both meat and vegetables is essential for maintaining a healthy lifestyle, especially for seniors.