Oysters are not called "milk of the sea" only for their protein. Their zinc content is on a different scale from other foods.
16.6 mg per 100 g. Beef sits at 4–5 mg and pumpkin seeds at about 7 mg — an order-of-magnitude difference. Zinc is directly involved in immune cell function, wound healing, taste, and male reproductive function.
Key benefits
Zinc is required for immunity and wound healing
Zinc is essential to T-cell maturation and function, and deficiency leaves you vulnerable to infection. The trials showing shorter colds with early zinc supplementation rest on this same role.
The link to male reproductive function is real
The folklore about oysters has a compositional basis. Zinc participates in sperm production and testosterone metabolism, and these decline in zinc deficiency. That does not mean more helps someone already replete.
Overwhelming in vitamin B12
100 g provides more than six times the daily requirement. B12 is needed for red cell formation and nerve function and is nearly absent from plant foods, making oysters valuable for anyone at risk of deficiency.
Iron in the heme form
5.1 mg per 100 g, and as heme iron it absorbs well — far less hindered by oxalate or phytate than plant-source iron.
How to eat it well
- For raw oysters, buy only those labelled for raw consumption. Handling standards differ from those meant for cooking.
- The habit of squeezing lemon makes sense nutritionally too: vitamin C aids iron absorption.
- Cooking them through eliminates norovirus risk. Heat all the way to the centre.
- Winter is the season. Summer oysters, during spawning, are worse on both flavour and safety.
- Zinc intake above 40 mg a day is not advisable, so skip zinc supplements on days you eat a lot of oysters.
What to watch out for
- They are a major route for norovirus and Vibrio infection. People who are immunocompromised, pregnant, or have liver disease should avoid raw oysters.
- Excess zinc causes copper deficiency. Avoid sustained high intakes.
- With gout, account for the purine content.
- Avoid entirely with shellfish or mollusc allergy.
- It is worth checking the harvest area for heavy metal contamination.
Nutrition
Approximate values per 100 g edible portion.
- Calories
- 68 kcal
- Protein
- 7.1 g
- Fat
- 2.5 g
- Carbohydrates
- 3.9 g
- Zinc
- 16.6 mg
- Vitamin B12
- 16 µg
- Iron
- 5.1 mg
- Selenium
- 63 µg
- Copper
- 1.6 mg
Key nutrients
- Zinc
- Vitamin B12
- Iron
- Selenium
- Copper