Coffee is a wonderful beverage that is loaded with antioxidants and other active compounds.
The active ingredient in regular coffee is caffeine, with each cup containing an average of 80–120 mg. A daily intake of 400 mg is generally considered to be safe.
However, consuming more than 500–600 mg per day can be excessive. This may overwhelm the nervous system, causing insomnia, nervousness, irritability, stomach cramps, heart palpitations and muscle tremors (32).
The amount of caffeine needed to experience these side effects differs widely between individuals.
Some can drink as much coffee as they want, while others experience symptoms with small amounts of caffeine.
Bottom Line: Coffee has been linked to many health benefits. However, too much caffeine may cause adverse effects in some people.
Organs are the most nutritious parts of animals, and liver is the most nutritious organ of all.
It is very rich in many essential nutrients, such as iron, B12, vitamin A and copper.
However, a 100 gram portion of beef liver contains more than six times the recommended dietary intake (RDI) of vitamin A, and 7 times the RDI of copper (33).
Vitamin A is a fat soluble vitamin, meaning it is stored in our bodies. Therefore, an excess may cause symptoms of vitamin A toxicity.
These symptoms may include vision problems, bone pain and an increased risk of fractures, nausea and vomiting (34).
Even though liver is incredibly healthy and nutritious, it should not be consumed daily. Eating it once per week is enough.
Bottom Line: Liver contains many essential nutrients. However, it is very rich in vitamin A and copper, which may cause problems in excessive amounts.
7. Cruciferous Vegetables
Cruciferous vegetables make up a large part of people’s daily vegetable intake. They have also become very popular as ingredients in various green smoothies and fresh vegetable juices.
Although cruciferous vegetables like broccoli are very healthy, adding high amounts to smoothies or green juices can contribute to a massive intake of these compounds.
People who are sensitive to thyroid problems should avoid consuming these veggies in very large amounts.
Bottom Line: Cruciferous vegetables are healthy and nutritious. However, they contain thiocyanates, which can block iodine absorption. People with thyroid problems should not eat very large amounts of these veggies.
8. Brazil Nuts
Brazil nuts are among the best dietary sources of selenium.
One large Brazil nut may contain up to 95 micrograms of selenium. This is more than the recommended daily amount for adults, and more than three times the amount required by children (49).
Eating only 4–5 Brazil nuts may leave an adult at the upper limit of safe selenium intake, so it is not recommended that you eat more than that.
Symptoms of selenium toxicity include loss of hair and nails, digestive issues and memory difficulties (50).
Bottom Line: Brazil nuts contain selenium, which is an essential trace element. However, selenium is toxic in high amounts. Therefore, only a few Brazil nuts should be eaten each day.