The same goes for pregnancy, where you essentially gain a deficiency because you're building another person inside you.

I'm D deficient. I took D supplements for a long time; m D levels never significantly increased.

If you think you have a deficiency, explain why to a doctor. A blood test to know for sure is simple. A doctor will know what kind of supplementation would best serve you, and there may be an underlying reason that can be treated to fix it.

I didn't say "no one should take supplements ever," I said most people who take supplements are doing so unnecessarily, and you should do so under the supervision of a physician.

You may have a specific deficiency, but your story does not constitute data.

There have been many studies that have addressed this specific issue. Literally billions of dollars are wasted every year on these supplements. If you have a healthy diet, you are very unlikely to need supplementation.

This is the availability bias, because your experience is normal for you, you unconsciously think your experience is more normal than it is.

Are you finding yourself deficient in vitamin K based on some symptom you're experiencing? Vitamin K is in soybeans, cashews, broccoli, chicken, grapes, blueberries, and a bunch of oils, including soybean, olive, and canola oils, and the list goes on and on. Vitamin K deficiency in adults is extremely rare.

Like every other vitamin and mineral, eating average healthy (and even lots of unhealthy) foods will meet your RDA.

200g of spinach sounds like a very reasonable amount for a single meal. I don't see the problem here.

Protein powder is a calorically dense food supplement, not a vitamin or mineral supplement

Gaining significant muscle mass and strength through heavy lifting requires adequate protein intake. It is extremely challenging to build the muscle needed to squat two or three times your body weight without dramatically increasing your protein consumption. Attempting to lift heavy weights without the proper nutritional support can lead to extended recovery times, increased injury risk, and wasted effort.

Whey protein powder can be a cost-effective and high-quality source of protein for those engaged in strength training. For individuals who lift weights regularly, protein powder can be an integral part of their training program and is not simply a gimmick. The notion that protein supplements are "snake oil" because the average person may not need them is flawed logic. The same could be said for weight training equipment, which would also be considered unnecessary for the general population, despite their benefits for those who strength train consistently.

The key is matching your nutritional intake, including protein consumption, to your training goals and needs. Dismissing helpful protein powder as snake oil simply because they may not benefit everyone is an oversimplification. The appropriate use of protein powder can be an important part of an effective strength training regimen for those who lift heavy weights.

Isn't there a limit of how much protein your body can absorb in a meal and the rest just gets metabolized/excreted.

Is your brother also mad into lifting weights? If not, they have no need for protein powder

Unless you're vegan, you're probably already getting more protein than you need.

Protein is needed for building muscles but most meatheads in the USA just eat all the protein and don't do enough of the exercise.

Only about 24% of people in the US aren't "overweight" to "obese."

Literally almost nobody needs this fucking protein because almost fuck-nobody is exercising.

https://en.wikipedia.org/wiki/Obesity_in_the_United_States

For the following statistics, "adult" is defined as age 20 and over. The overweight + obese percentages for the overall US population are higher reaching 39.4% in 1997, 44.5% in 2004, 56.6% in 2007, 63.8% (adults) and 17% (children) in 2008,in 2010 65.7% of American adults and 17% of American children are overweight or obese, and 63% of teenage girls become overweight by age 11. In 2013 the Organization for Economic Co-operation and Development (OECD) found that 57.6% of all American citizens were overweight or obese. The organization estimated that 3/4 of the American population would likely be overweight or obese by 2020. According to research done by the Harvard T.H. Chan School of Public Health, it is estimated that around 40% of Americans are considered obese, and 18% are considered severely obese as of 2019. Severe obesity is defined as a BMI over 35 in the study. Their projections say that about half of the US population (48.9%) will be considered obese and nearly 1 in 4 (24.2%) will be considered severely obese by 2030.

What many US citizens need is portion control and regular exercise.